Term Index (S)

 S0  S2  S3  S5  S8  SA  SB  SC  SD  SE  SF  SG  SH  SI  SK  SL  SM  SN  SO  SP  SQ  SR  SS  ST  SU  SV  SW  SX  SY  SZ

• S (Poynting vector): measures directional energy flux density
• S (S-type star): type of star with lines indicating zirconium
• S (entropy): relative measure of the amount of usable energy available
• S (sensitivity function): function of wavelength giving the sensitivity of an instrument
• S (siemens): SI unit of electrical conductance
• S (source function): measure indicating the effect of a material on EMR passing through
• S (spectral flux density): flux or power of radiation per unit area per unit wavelength
• S (sulfur): metal, S, atomic number 16
• S: see Sharpless Catalog
• S: see double star designation
• S Cluster (S-Star Cluster): stellar cluster at the center of the Milky Way
• S Doradus variable (luminous blue variable): type of extremely bright variable stars
• S Doradus variable: see variable star
• S orbital: see electron orbital
• S star: see S-Star Cluster
• Sérsic index: see Sérsic profile
• Sérsic law (Sérsic profile): model of the relative surface brightness across a galaxy
• Sérsic model (Sérsic profile): model of the relative surface brightness across a galaxy
• Sérsic profile: model of the relative surface brightness across a galaxy
  • de Vaucouleurs' profile: relation between elliptical galaxy surface brightness and distance from center
  • surface brightness profile: curve of a galaxy's brightness from center to edge
• S&T (Sky & Telescope): amateur astronomy publication
• S-class: see S-type star
• S-index (chromospheric activity index): measure of magnetic activity of a star's chromosphere
• s-process: synthesis of elements through neutron capture and beta decay
  • neutron capture: combination of an atomic nucleus and a neutron
  • r-process: synthesis of elements through neutron capture faster than beta decay
• S-Star Cluster: stellar cluster at the center of the Milky Way
• S-type star: type of star with lines indicating zirconium
  • technetium star: star showing technetium absorption lines
• S/m: see siemens
• S/N (signal-to-noise ratio): ratio of the power of a signal to the power of the background noise
• S0 (lenticular galaxy): disk galaxy that has no spirals
• S0 galaxy (lenticular galaxy): disk galaxy that has no spirals
• S2: see S-Star Cluster
• S3MC: see Spitzer Space Telescope
• S5 (Southern Stellar Stream Spectroscopic Survey): spectroscopic survey of seven southern-hemisphere stellar streams
• S5: see Strong Source Surveys
• S8: see sigma-8 tension
• S8 tension (sigma-8 tension): Lambda CDM anomaly regarding matter fluctuation
• S82 (Stripe 82): SDSS field in southern hemisphere
• S₁: see Stokes parameters
• S₂: see Stokes parameters
• S₃: see Stokes parameters
• S₄: see Stokes parameters
• S₈ tension (sigma-8 tension): Lambda CDM anomaly regarding matter fluctuation
• S_N: see globular cluster
• S⁵ (Southern Stellar Stream Spectroscopic Survey): spectroscopic survey of seven southern-hemisphere stellar streams
• SA: see AGILE
• SA: see IRAS
• SA: see rare designator prefixes
  • spiral galaxy: flat galaxy with spiraling arms
• Sa: see rare designator prefixes
• SAA: see Van Allen belts
• SAAO (South African Astronomical Observatory): South African observatory with SALT telescope
  • Infrared Survey Facility: 140 cm reflector telescope that images in infrared
  • MeerLICHT: South African telescope coordinated with MeerKAT
  • Southern African Large Telescope: 10-meter telescope in South Africa
• SAB: see galaxy classification
  • NGC 6946: face-on spiral galaxy
  • spiral galaxy: flat galaxy with spiraling arms
• SABER: see TIMED
• SABOCA: see Atacama Pathfinder Experiment
• SABRE: see DAMA/LIBRA
• SAC (Shapley-Ames Catalog): 1932 catalog of contemporary data on 1249 galaxies
• Sachs-Wolfe effect: gravitational redshift of the CMB
• Sacramento Peak
• National Solar Observatory: US government sponsored solar observatory
• SACS: see rare designator prefixes
• sad trombone: see fast radio burst
• SAF (Société astronomique de France): French non-profit astronomical society
• SAFARI: see SPICA
• Sag A*: SMBH at the center of Milky Way
  • Fermi bubbles: gamma-ray features associated with Milky Way center
• Sag DEG (Sagittarius Dwarf Elliptical Galaxy): satellite galaxy of the Milky Way
• SagDIG (Sagittarius Dwarf Irregular Galaxy): most distant galaxy in the Local Group
• SAGE: survey of gas and dust in the Magellanic Clouds
• SAGE-LMC: see SAGE
• SAGE-SMC: see SAGE
• SAGE-Spec: see SAGE
• Sagittarius A* (Sag A*): SMBH at the center of Milky Way
  • Event Horizon Telescope: growing VLBI network
  • SGR J1745-2900: magnetar orbiting the Milky Way SMBH
• Sagittarius A*: see galactic center
• Sagittarius A* Cluster (S-Star Cluster): stellar cluster at the center of the Milky Way
• Sagittarius B2 (Sgr B2): GMC near the galactic center
• Sagittarius Dwarf Elliptical Galaxy: satellite galaxy of the Milky Way
  • Field of Streams: region of sky crossed by a number of stellar streams
  • Milky Way subgroup: the Milky Way and its satellites
• Sagittarius Dwarf Irregular Galaxy: most distant galaxy in the Local Group
• Sagittarius Dwarf Spheroidal Galaxy (Sagittarius Dwarf Elliptical Galaxy): satellite galaxy of the Milky Way
• Sagittarius Stream: see Sagittarius Dwarf Elliptical Galaxy
  • Field of Streams: region of sky crossed by a number of stellar streams
• Sagittarius Window Eclipsing Extrasolar Planet Search: transit search using HST time
• Sagittarius-Carina Arm: see spiral arm
• Sagnac effect: an effect of the movement of light beams regarding their interference
• Saha equation: equation relating ionization to temperature
• Saha ionization equation (Saha equation): equation relating ionization to temperature
• Saha-Langmuir equation (Saha equation): equation relating ionization to temperature
• SAINT-EX: see SPECULOOS
• Saiph
• Orion: well-known constellation in the northern hemisphere
• SALE: see iSALE
• Salpeter function: see initial mass function
• Salpeter IMF: see initial mass function
• Salpeter time (Salpeter timescale): timescale for black hole growth
• Salpeter timescale: timescale for black hole growth
• SALT (Southern African Large Telescope): 10-meter telescope in South Africa
  • RESOLVE­: galaxy and gas survey limited to 65-100 Mpc
  • South African Astronomical Observatory: South African observatory with SALT telescope
• SALTICAM: see Southern African Large Telescope
• SAM (semi-analytic model): cosmological model combining analytic and other methods
• SAM: see Mars Science Laboratory
• SAM: see SOAR Telescope
• SAM QC: see Mars Science Laboratory
• SAM-FP: see SOAR Telescope
• SAM-QMS: see Mars Science Laboratory
• SAM-TLS: see Mars Science Laboratory
• SAMI: see Anglo-Australian Telescope
• Sample Acquisition System: see CAESAR
• sampling bias: see selection bias
• sampling error: see selection bias
• Samuel Oschin Telescope (Palomar 48 Inch Telescope): 48 inch Schmidt telescope at Palomar Observatory
• SAN: see rare designator prefixes
• SAND: see rare designator prefixes
• SANE
• AGN accretion: an SMBH's accretion, such as powers AGNs/quasars
• sanity check: see back-of-the-envelope calculation
• Santa Barbara Instrument Group: old name of Santa Barbara Scientific, telescope instrument manufacturer
• Santa Cruz
• semi-analytic model: cosmological model combining analytic and other methods
• SAO: see Center for Astrophysics
• SAO: see SAO Star Catalog
  • Astrophysics Data System: online astrophysics bibliography and paper archive
  • CfA Redshift Survey: 1970s-1990s surveys of galaxy redshifts
  • Fred Lawrence Whipple Observatory: observatory near Amado, Arizona
• SAO Star Catalog: 1960s catalog
• SAO/ASIAA
• Academia Sinica Institute of Astronomy and Astrophysics: Taiwanese astrophysics research organization
• SAO/NASA Astrophysics Data System (Astrophysics Data System): online astrophysics bibliography and paper archive
• SAPTA: see MeerKAT Pulsar Timing Array
• SAR (synthetic aperture radar): method of using moving radar with a stationary target
• SARA (Society of Amateur Radio Astronomers): US organization
• SARAS: survey aiming at highly-redshifted 21-cm detection
• SARAS 1: see SARAS
• SARAS 2: see SARAS
• SARAS 3: see SARAS
• Sardinia Radio Telescope: Italian large single-dish radio telescope
  • European Pulsar Timing Array: European collaboration of radio telescopes
• SARG: see Telescopio Nazionale Galileo
• SAS (XMM-Newton Science Analysis System): software designed to analyze XMM-Newton X-ray data
• SAS: see CAESAR
• SAS 1 (Uhuru): 1970 X-ray space telescope
• SAS 2 (Small Astronomy Satellite 2): 1970s NASA gamma ray space telescope
• SAS 3 (Small Astronomy Satellite 3): 1970s NASA X-ray space telescope
• SAS-A (Uhuru): 1970 X-ray space telescope
• SAS-B (Small Astronomy Satellite 2): 1970s NASA gamma ray space telescope
• SAS-C (Small Astronomy Satellite 3): 1970s NASA X-ray space telescope
• SAS-D (International Ultraviolet Explorer): 1980s ultraviolet space telescope
• Saskatoon: 1990s survey to measure CMB anisotropy
• SASS: see CubIXSS
• SASSy: see SCUBA
• SaSt: see rare designator prefixes
• SAT: see Simons Observatory
• SAT: see aperture synthesis
• satcon (satellite constellation): group of many coordinated satellites such as for communication
• Satech-01: Chinese experimental spacecraft
• satellite: see moon
  • exosatellite: natural satellite not in the solar system
• satellite constellation: group of many coordinated satellites such as for communication
• satellite constellation: type of communication system incorporating tens/hundreds of satellites
  • Kessler syndrome: low-Earth-orbit debris growing out of control
• satellite galaxies
• hypergalaxy: sizeable spiral galaxy with satellites
• Magellanic Clouds: two nearby galaxies
• satellite galaxy: galaxy that orbits a larger galaxy
• satellite mega-constellation (satellite constellation): group of many coordinated satellites such as for communication
• satellite plane problem: satellite galaxies inexplicably tend to fall in a plane
• saturated Hanle effect: see Hanle effect
• saturation: see humidity
  • hydrocarbon: any compound of just carbon and hydrogen
• Saturn: second largest planet in the solar system
  • Cassini: explorer spacecraft sent to Saturn
  • Dragonfly: Titan flying rover under development
  • Enceladus: Saturn moon considered possible carrier of life
  • Enceladus Life Finder: mission to search for life on Saturn moon Enceladus
  • Enceladus Orbilander: concept for a NASA mission to Enceladus
  • giant planet: planet of more than 10 Earth masses
  • grand tack hypothesis: solar system formation model with Jupiter and Saturn migrating
  • gravity sounding: measuring a planet's gravitation field by study of nearby probe flights
  • helium rain: possible source of heat in giant planet atmospheres
  • ring system: disk or set of rings orbiting a planet
  • shepherd moon: small moon affecting outer edge of a planet's ring
  • solar system object: the Sun, solar system planets, minor planets, comets, and moons
  • TAM: non-gray-RT 3D model of Titan's atmosphere
  • Titan: well-known Saturn moon
  • Voyager: space probes to observe planets and the edge of the solar system
• Saturn II (Enceladus): Saturn moon considered possible carrier of life
• Saturn V
• Space Launch System: launch rocket in development, e.g., for future astronomical projects
• Saturn VI (Titan): well-known Saturn moon
• Saurer: see rare designator prefixes
• SAURON: see William Herschel Telescope
  • integral field spectrograph: spectrograph that captures images
  • integral field unit: instrument to allow a spectrograph to capture data over a 2D field
• SAVAL (Sociedad Astronómica de Valparaíso y Viña del Mar): Chilean amateur astronomy society
• SaWe: see rare designator prefixes
• SAX: see BeppoSAX
• SAXO: see European Southern Observatory Very Large Telescope
• SAXO: see SPHERE
• SB (spectroscopic binary): binary star detected by movement indicated by Doppler shifts in the spectrum
• SB (surface brightness): brightness per unit area of a surface
• SB: see rare designator prefixes
  • spiral galaxy: flat galaxy with spiraling arms
• SB1: see double-line spectroscopic binary
• SB1: see spectroscopic binary
• SB2 (double-line spectroscopic binary): spectroscopic binary star where a specific line shows up at two different wavelengths
  • spectroscopic binary: binary star detected by movement indicated by Doppler shifts in the spectrum
• SBB: see Big Bang
• SBF (surface brightness fluctuation): apparent indication of an elliptical galaxy's distance
• SBH: see supermassive black hole
• SBIG (Santa Barbara Instrument Group): old name of Santa Barbara Scientific, telescope instrument manufacturer
• SBIG STX-6303: see Las Cumbres Observatory
• SBNC (Small Bodies Names Committee): old name of IAU Committee for Small Body Nomenclature
• SBS (Second Byurakan Survey): 1970s-1990s survey of galaxies and quasars
• SBS 0335-052: blue compact galaxy
• SC (stellar cluster): group of stars apparently formed by a single cloud
• SC: see rare designator prefixes
• scalar boson
• standard model: model of elementary particles including quarks
• scalar curvature: see curvature
• scalar field: see mathematical field
• scalar field dark matter (fuzzy dark matter): concept of extremely light dark matter particles
• scalar spectral index: see Lambda-CDM model
• scalar-tensor gravity: GR-like gravity that incorporates a scalar field
  • f(R) gravity: class of modifications to general relativity
• scalar-tensor-vector gravity: see scalar-tensor gravity
• scale
• astronomical quantities: some astronomy amounts/numbers
• scale factor: relative size of the universe as a function of time
  • comoving units: units of measure that incorporate the scale factor
  • star formation rate: rate at which material such as gas is turned into stars
• scale height: measure of exponential falloff
• scale length: see scale height
  • surface brightness profile: curve of a galaxy's brightness from center to edge
• scaling relation: see standard candle
• scan pattern: see intensity mapping
• scan speed: the speed at which the telescope changes angle on the sky while observing
  • intensity mapping: measure of cosmic matter density
• scandium
• Am star: A-type star with metallic lines
• SCAP: 1980s balloon-borne ultraviolet telescope
• SCAP-1909: see SCAP
• SCAP-2000: see SCAP
• SCARLET: see atmospheric model
• scatter broadening: see fast radio burst
• scatter plot: plot of points within two dimensions
• scatter plot matrix: see scatter plot
• scattered disk
• trans-Neptune object: minor planet beyond Neptune
• scattered disk object
• trans-Neptune object: minor planet beyond Neptune
• scattered disk objects
• solar system object: the Sun, solar system planets, minor planets, comets, and moons
• scattered Kuiper belt object
• trans-Neptune object: minor planet beyond Neptune
• scattered light: see stray light
• scattering: changing the direction of a particle's movement
  • emission: addition of photons to a beam of EMR
• scattering angle: see cross section
• scattering coefficient: see absorption coefficient
• SCE: see Ulysses
• SCExAO: see Subaru Telescope
  • extreme adaptive optics: high-performance version of AO system
• SCF (supercritical fluid): state of matter at sufficient pressure and temperature
• Schönberg-Chandrasekhar limit: maximum stellar isothermal helium core mass
• Schechter function: see luminosity function
• Schechter luminosity function: see luminosity function
• Schiaparelli: see ExoMars
• Schiaparelli: see Trace Gas Orbiter
• Schiefspiegler: type of off-axis reflector telescope
• Schmidt camera: telescope type with a very wide field of view
  • field curvature: focusing to a curved surface rather than a plane
  • spherical aberration: mis-focusing by spherically-curved mirrors and lenses
• Schmidt corrector plate: see Schmidt camera
  • aspheric mirror: mirror with other than a spherical curvature
  • field curvature: focusing to a curved surface rather than a plane
  • Schmidt-Newton telescope: type of reflector telescope
  • spherical aberration: mis-focusing by spherically-curved mirrors and lenses
• Schmidt law (Kennicutt-Schmidt law): relation between gas density and star formation rate
• Schmidt telescope (Schmidt camera): telescope type with a very wide field of view
  • aspheric mirror: mirror with other than a spherical curvature
• Schmidt-Cassegrain telescope: see Schmidt camera
• Schmidt-Newton telescope: type of reflector telescope
  • Schmidt camera: telescope type with a very wide field of view
• Schmidt-Newtonian telescope (Schmidt-Newton telescope): type of reflector telescope
• Schoenberg: see rare designator prefixes
• Scholz's Star: nearby binary star with red dwarf and brown dwarf
• Schrödinger equation: quantum-mechanical wave-equation-like equation
• Schrödinger-Newton equation (Schrödinger-Poisson equation): Schrödinger equation including a term for gravity
• Schrödinger-Poisson equation: Schrödinger equation including a term for gravity
• Schroedinger equation
• Schrödinger-Poisson equation: Schrödinger equation including a term for gravity
• Schuster-Schwarzschild approximation (Schuster-Schwarzschild model): simplified model of a star's production of absorption lines
• Schuster-Schwarzschild model: simplified model of a star's production of absorption lines
• Schwarzschild black hole: see black hole model
  • gravitational singularity: point where density and gravity reach infinity
  • Kerr black hole: spinning black hole with no charge
• Schwarzschild density: see Schwarzschild radius
• Schwarzschild diameter: see Schwarzschild radius
• Schwarzschild lens: see gravitational lensing
• Schwarzschild metric: see metric
• Schwarzschild object: see black hole model
• Schwarzschild radius: radius of a black hole's event horizon
  • black hole shadow: dark-disk appearance of a black hole viewed from a distance
  • event horizon: surface-shape around a black hole through which light cannot escape
• Schwarzschild telescope: type of two-mirror reflector telescope
  • aspheric mirror: mirror with other than a spherical curvature
• Schwarzschild throat: see wormhole
• Schwarzschild wormhole: see wormhole
• Schwarzschild-Couder Telescope
• Cherenkov Telescope Array: ground gamma-ray telescope array in development
• Schwarzschild-Couder telescope
• Schwarzschild telescope: type of two-mirror reflector telescope
• SCI: see Hayabusa2
• science
• abundances: relative amounts of each chemical element
• asteroseismology: study of stars through analysis of their pulsation
• astrobiology: study of extra-terrestrial life
• astrometry: precise measurement of the position and movement of stars
• astronomy: study of astronomical objects and their environments
• astrophysics: physics applied to astronomy
• basal: from the base or from below
• basalt: an igneous rock type that shows rapid cooling
• bathymetry: study and measurement of sea depths
• blind analysis: performing experimental analysis without knowing the data
• cosmology: study of the life of the universe
• cryogenic spectroscopy: laboratory spectroscopy of materials cooled to cryogenic temperatures
• decadal survey: type of once-a-decade planning report from NASA and the NAS
• European Research Infrastructure Consortium: science and technology initiative
• extragalactic astronomy: astronomy of other galaxies, galaxy clusters, AGNs, quasars, etc.
• fiducial: taken as a standard
• forward model: model producing potential observable values from parameters
• galactic astronomy: astronomy confined to the Milky Way
• geochemistry: the chemistry of the Earth, planets, and moons
• Goddard gravity model: gravity model produced by Goddard Space Flight Center
• gravimetry: measurement of gravity's strength
• hydrology: study of the movement of water
• in situ: on site
• interferometry: analysis of superimposed EMR waves
• interstellar astrophysics: astronomy of the ISM including dust and clouds
• Kavli Institute: any of a number of science institutes supported by Kavli Foundation
• low frequency radio astronomy: astronomy using the lower end of the radio spectrum
• millimeter astronomy: observation and analysis at wavelengths on the order of a millimeter
• optics: science and technology regarding visible light
• photochemistry: study of the chemical effects of light
• photometry: studying starlight using optical filters
• planetary protection: the principle of avoiding the contamination of planets with Earth life forms
• planetary science: study of planet characteristics
• plasma astrophysics: includes cosmology, IGM, ISM, HI regions
• polarimetry: measurement of polarization of EMR
• principal investigator: lead researcher in a scientific endeavor
• Python: programming language used for a lot of astrophysics research
• radio astronomy: astronomy observation and analysis of radio EMR
• radio science: radar and other methods of using radio to probe planets and moons
• relativistic astrophysics: physics applicable to cosmology and strong field gravity
• RMS astronomy: collective term for radio, millimeter, and submillimeter
• scale height: measure of exponential falloff
• search for extraterrestrial intelligence: search for radio signals sent from extraterrestrial sources
• selection bias: selection of a sample set that is not appropriately randomized
• sigma: indication of the confidence level of an experiment
• SIMSTACK: software to correlate intensity maps with sources
• solar physics: study of the physics of the Sun
• spectrography: charting the strengths of different electromagnetic wavelengths
• spectrometry: measuring the strengths of different electromagnetic wavelengths
• spectroscopy: measurement of light with various electromagnetic wavelengths
• stellar astronomy: astronomy of the birth, structure, variety, evolution, and fate of stars
• stratigraphy: study of rock layering
• submillimeter astronomy: astronomy observation and analysis of borderline infrared EMR
• synoptic: general, covering everything
• synthetic photometry: deriving photometry-style data from spectroscopy
• thermodynamics: physics of heat and energy
• time-domain astronomy: observing and analyzing changes in astronomical objects
• tomography: observation of sections of a 3D object
• tortuosity: describes something curved with many twists and turns
• transient astronomy: study of short-term astronomical phenomena
• ultraviolet astronomy: astronomy observation and analysis of UV
• Science and Engineering Research Council: old name of UK's EPSRC
• Science and Technology Facilities Council, UK: UK research agency
• Science Instrument Module: see Chandra X-ray Observatory
• Science Run: see LIGO
• scientific notation
• dex: a number or ratio's log base 10
• scintillation (twinkling): blinking, apparent movement and color changes of observed stars
• scintillation: see scintillator
• scintillation: see scintillometry
  • diffractive interstellar scintillation: diffraction of star light by the ISM
  • point source: celestial object that focuses to a point or single Airy disk
  • refractive interstellar scintillation: refraction of star light by the ISM
• scintillator: instrument part designed to respond to high-energy photons
  • Compton telescope: type of gamma ray telescope for 0.75-30 MeV range
• scintillometer: see scintillometry
• scintillometry: measuring of twinkling
• SCIP: see STEREO
• SciPy: Python library for scientific programming
• SCJ: see double star designation
• SCl: see supercluster
• SCl 117 (Coma Supercluster): nearby supercluster
• SCl 128 (Hydra-Centaurus Supercluster): near neighbor of Local Supercluster
• SCl 40 (Perseus-Pisces Supercluster): nearby supercluster
• SCM: see Magnetospheric Multiscale Mission
• SCM: see rare designator prefixes
  • THEMIS: set of satellites studying the Earth's magnetic field
• Sco OB2 (Scorpius-Centaurus Association): nearby OB association
• Sco-Cen (Scorpius-Centaurus Association): nearby OB association
• SCORPIO: see Large Altazimuth Telescope
• SCORPIO-2: see Large Altazimuth Telescope
• Scorpius-Centaurus Association: nearby OB association
  • CTIO Upper-Scorpius OB Association Survey: survey of low-mass stars and brown dwarfs
  • OB association: stellar association including O and/or early B class stars
• Scott effect: bias toward finding clusters that have bright galaxies
• SCP (Supernova Cosmology Project): used supernova data to determine a history of the universe's expansion
• SCP: see SUNRISE
• SCR: see SuperCOSMOS Sky Survey
• SCR: see solar energetic particle
• SCT: see Schmidt camera
  • Cherenkov Telescope Array: ground gamma-ray telescope array in development
• SCUBA: submillimeter instrument on James Clark Maxwell Telescope
• SCUBA-1: see SCUBA
• SCUBA-2: see James Clerk Maxwell Telescope
• SCUBA-2: see SCUBA
  • AMUSE²: survey of ELANs
  • JINGLE: survey of dust and gas in galaxies
• SCUBA-2 All Sky Survey: see SCUBA
• SCUBA-2 Ambitious Sky Survey: see SCUBA
• Sculptor Dwarf
• Milky Way subgroup: the Milky Way and its satellites
• Sculptor Galaxy (NGC 253): spiral galaxy 11 million light-years away
• Sculptor Void
• Sculptor Wall: large slab of galaxies
• Sculptor Wall: large slab of galaxies
  • galaxy filament: thread-like formations of galaxies, 50 to 80 megaparsecs
• Scutum-Centaurus Arm: one of two spiral galaxy arms from the Milky-Way bar
• Scutum-Centaurus Arm: see spiral arm
• Scutum-Crux Arm (Scutum-Centaurus Arm): one of two spiral galaxy arms from the Milky-Way bar
• SD: see Type Ia supernova problem
• SD: see supernova progenitor
  • Type Ia supernova: type of supernova for which distance can be determined
• sd (subdwarf): star less bright than the main sequence given its spectral class
  • luminosity class: classification of size/luminosity of stars
• SD2: see Rosetta
• SDC: see Hale Telescope
• SDF (Subaru Deep Field): survey of a small region of the sky using the Subaru telescope
• SDI: see speckle suppression
• SDIC (Solar Influences Data Analysis Center): Royal Observatory of Belgium division on solar weather data
• SDO (Solar Dynamics Observatory): 2010 satellite observing the Sun
  • trans-Neptune object: minor planet beyond Neptune
• SDOR: see variable star
• SDOs
• solar system object: the Sun, solar system planets, minor planets, comets, and moons
• SDP: see Magnetospheric Multiscale Mission
• SDSS (Sloan Digital Sky Survey): imaging survey of 500,000,000 objects in 35% of sky
  • 2dF-SDSS LRG and QSO survey: spectroscopic survey of distant galaxies
  • Baryon Oscillation Spectroscopic Survey: survey of spatial distribution of luminous red galaxies and quasars
  • GD-1: stellar stream formed by globular cluster
  • Monoceros Ring: stellar stream wrapping around the Milky Way
  • Orphan stream: stellar stream wrapping around the Milky Way
  • Virgo Stellar Stream: stellar stream wrapping around the Milky Way
• SDSS IV
• MaNGA Stellar Library: catalog of SEDs of representative stars
• SDSS J065133.34+284423.4 (WD J0651+2844): binary pair of closely-orbiting white dwarfs
• SDSS photometric system (ugriz photometric system): photometric system used for SDSS
• SDSS Stripe 82 (Stripe 82): SDSS field in southern hemisphere
• SDSS-DR12 Quasars: catalog of quasar information in SDSS DR12
• SDSS-DR12Q (SDSS-DR12 Quasars): catalog of quasar information in SDSS DR12
• SDSS-DR16 Quasars: catalog of quasar information in SDSS DR16
• SDSS-DR16Q (SDSS-DR16 Quasars): catalog of quasar information in SDSS DR16
• SDSS-I: see Sloan Digital Sky Survey
  • ugriz photometric system: photometric system used for SDSS
• SDSS-II: see Sloan Digital Sky Survey
• SDSS-III: see Sloan Digital Sky Survey
  • APOGEE: SDSS near-infrared survey of stars
• SDSS-IV: see Sloan Digital Sky Survey
• SDSS-V: see Sloan Digital Sky Survey
  • Milky Way Mapper: SDSS spectrographic survey of Milky Way stars
• SDSSp: see Sloan Digital Sky Survey
• SE: see double star designation
• sea level
• gravitational potential model: mathematical model of an astronomical body's gravitational field
• J₂: geopotential coefficient regarding a planet's oblateness
• SEAAN (Southeast Asia Astronomy Network): astronomy research/education organization
• search for extraterrestrial intelligence: search for radio signals sent from extraterrestrial sources
  • Allen Telescope Array: array of radio telescopes in northern California for SETI
  • Drake equation: estimate of advanced life in the Milky Way
• Search for Habitable Planets Eclipsing Ultra-cool Stars (SPECULOOS): search for Earth-like exoplanets orbiting nearby dim stars
• sec (arcsecond): a 3600th of an angular degree
• SECCHI: see STEREO
• second (arcsecond): a 3600th of an angular degree
• second: see right ascension
• Second Byurakan Survey: 1970s-1990s survey of galaxies and quasars
• second dredge-up: see dredge-up
• second of arc (arcsecond): a 3600th of an angular degree
• second of right ascension: see arcsecond
• second order perturbation problem: see perturbation theory
• Second Palomar Observatory Sky Survey: see Palomar Observatory Sky Survey
• Second Reference Catalogue of Bright Galaxies: see Reference Catalogue of Bright Galaxies
• second-order TOF: see theory of figures
• secondary anisotropies: see CMB anisotropies
• secondary eclipse: eclipse of a body that also transits
  • exoplanet eclipse light curve: graph of light as an exoplanet transits in front of its star
  • transit: a celestial body passing between another and an observer
• secondary mirror: see primary mirror
  • Korsch telescope: type of three-mirror reflector telescope
  • Nasmyth telescope: type of reflector telescope with secondary and tertiary mirrors
  • three-mirror anastigmat: general type of reflector telescope
• secondary modes: see CMB polarization
• sectorial coefficients
• gravitational potential model: mathematical model of an astronomical body's gravitational field
• secular: occurring slowly over a long period of time
  • Laplace radius: a radius for a stable orbit of a satellite around a planet
• secular evolution: see secular
  • quenched galaxy: galaxy currently producing minimal stars
• secular GI: see gravitational instability
• secular gravitational instability: see gravitational instability
• secular motion: see secular
• secular parallax: see parallax
• secular resonance: see orbital resonance
• secular variation: see secular
• SED (spectral energy distribution): function or plot of brightness at each wavelength in the spectrum
  • spectral power distribution: function of power versus wavelength or frequency
• SED fitting: see spectral energy distribution
• sedimentation: settling of heavier material to the bottom
• SEDM: see Palomar 60-inch Telescope
• Sedna: distant solar system planetoid discovered in 2003
  • Kuiper Belt: further part of solar system beyond Neptune
  • trans-Neptune object: minor planet beyond Neptune
• sednoid: see trans-Neptune object
• Sedov expansion: see blastwave
• Sedov length: see blastwave
• Sedov-Taylor expansion: see blastwave
• Sedov-Taylor phase: see supernova remnant
• SEDS (Spitzer Extended Deep Survey): survey of galaxy mass and black holes through life of the universe
• SEDS (Students for the Exploration and Development of Space): student-run organization focused on space exploration
• SEDs
• Herschel Orion Protostar Survey: survey of SEDs of YSOs in Orion
• SEE: see TIMED
• SEE: see double star designation
• seeing: apparent blurring and twinkling of objects seen through atmosphere
• seeing limited: see diffraction limited
• seeing limited: see seeing
• seeing number: see seeing
• segmented mirror: a telescope mirror formed of an array of smaller mirrors
• SEGUE: see Sloan Digital Sky Survey
• Segue: see Sloan Digital Sky Survey
• Segue 1
• Milky Way subgroup: the Milky Way and its satellites
• Segue 2
• Milky Way subgroup: the Milky Way and its satellites
• Segue 3: faint star cluster i the constellation Pegasus
• SEGUE-2: see Sloan Digital Sky Survey
• SEI: see double star designation
• Seidel aberrations: see aberration
• Seidel errors: see aberration
• SEIS: see InSight
• seismic waves: waves broadcast through Earth from earthquakes
• seismograph: see quake
• seismology: see seismic waves
  • normal mode: resonant surface waves in seismology
• seismometer: see quake
• selection bias: selection of a sample set that is not appropriately randomized
• selectron: see supersymmetry
• SELENE: 2007-2008 Japanese lunar probe
• Selenological and Engineering Explorer (SELENE): 2007-2008 Japanese lunar probe
• self-absorption: EMR absorption by the same substance that emitted it
• self-gravitating body: see self-gravitation
• self-gravitation: gravitational force holding a body together
• self-gravity (self-gravitation): gravitational force holding a body together
• self-interacting dark matter: see atomic dark matter
• semi-analytic model: cosmological model combining analytic and other methods
• semi-analytical model
• GALFORM: semi-analytic galaxy formation model
• semi-heavy water: see deuterium
• semi-major axis: maximum radius of an ellipse
• semi-minor axis: see semi-major axis
• semiconductor detector: see particle spectrometer
• semidetached binary: see binary star
• semidetached binary: see contact binary
• semimajor axis
• orbital element: parameters describing an orbit
• semiregular variable: see variable star
  • pulsating star: variable star that varies through energy pulses
• sensitivity: see balanced accuracy
• sensitivity function: function of wavelength giving the sensitivity of an instrument
• sensor plane (focal plane): plane within optical system at which an image is in focus
• sensor tilt: see focal plane tilt
• SEP (solar energetic particle): high-energy particles from the Sun
• SEP: see MAVEN
  • UVSC Pathfinder: instrument to observe the Sun
• separation
• projected separation: lower limit on distance between two objects in same part of the sky
• SEPIA: see Atacama Pathfinder Experiment
  • DeGaS-MC: APEX survey of potential star formation regions in the Magellanic Clouds
• SEPICA: see Advanced Composition Explorer
• SEQUELS: see Baryon Oscillation Spectroscopic Survey
• SEQUOIA: see Large Millimeter Telescope
• SERC (Science and Engineering Research Council): old name of UK's EPSRC
  • IRAS: 1983 satellite that surveyed the sky in infrared
  • UK Schmidt Survey: photographic survey of the southern hemisphere sky
• series: see series expansion
• series approximation: see series expansion
• series expansion: arithmetic series whose limit is equal to a function
  • Euler's formula: formula relating exponentials to trigonometric functions
  • Fourier series expansion: type of series expansion of a function using trigonometric functions
• Serpens Cloud: molecular cloud with SF regions
• Serpens Main: see Serpens Cloud
• Serpens Molecular Cloud (Serpens Cloud): molecular cloud with SF regions
• Serpens South: see Serpens Cloud
• Serrurier truss
• Hale Telescope: 5.1 m reflector telescope in California
• Sersic: see rare designator prefixes
• service
• Astronomer's Telegram: service reporting transients and discoveries
• SERVS (Spitzer Extragalactic Representative Volume Survey): infrared survey of some well-studied fields
  • Spitzer Space Telescope: retired infrared space telescope
• SES: see STELLA
• SESAME: see Rosetta
• SESN: see core collapse supernova
• SEST (Swedish-ESO Submillimetre Telescope): 1990s 15 m submillimeter telescope in Chile
• SEST (Swedish-ESO Submillimetre Telescope): former 15 m radio telescope array in Chile
  • Africa Millimetre Telescope: planned 15 m radio telescope array in Namibia
• Set of Identifications, Measurements and Bibliography for Astronomical Data (SIMBAD): online database of astronomical objects
  • Centre de données astronomiques de Strasbourg: repository of astronomical data
• SETI (search for extraterrestrial intelligence): search for radio signals sent from extraterrestrial sources
  • Allen Telescope Array: array of radio telescopes in northern California for SETI
  • Breakthrough Listen: SETI survey using GBT and Parkes Observatory
  • Drake equation: estimate of advanced life in the Milky Way
  • High Resolution Microwave Survey: 1990s microwave SETI search
• SETI Institute: see search for extraterrestrial intelligence
  • Allen Telescope Array: array of radio telescopes in northern California for SETI
• Sextans: see rare designator prefixes
• Sextans Dwarf Spheroidal
• Milky Way subgroup: the Milky Way and its satellites
• Seyfert
• 3C 303: Seyfert galaxy of interest
• Circinus Galaxy: nearest Seyfert galaxy
• IRAS 13224-3809: active Seyfert galaxy with well-studied SMBH
• Messier 106: spiral galaxy with maser
• Messier 77: easily-observed spiral galaxy
• NGC 7469: spiral galaxy with AGN outflow
• Whirlpool Galaxy: easily-observed spiral galaxy
• Seyfert galaxy: visible active galaxy
  • active galactic nucleus: central region of a galaxy with extremely high luminosity
• SF (star formation): theorized collapse of gas and dust into stars
• SF main sequence (galaxy main sequence): relation between galaxies' star formation and stellar mass
• SF rate (star formation rate): rate at which material such as gas is turned into stars
• SF region (star-forming region): area forming stars and/or ready for star formation
• SFA: see eXTP
• SFE: see star formation rate
• SFG: see galaxy main sequence
• SFG: see starburst galaxy
• SFH (star formation history): star formation rate as a function of time
• SFH Camera: see Fred Young Submillimeter Telescope
• SFM (synthetic field method): method of testing galaxy opacity
• SFO: see rare designator prefixes
• SFR (star formation rate): rate at which material such as gas is turned into stars
• SFR (star-forming region): area forming stars and/or ready for star formation
  • Cygnus-X: well-studied massive SF region
  • NGC 2363: low-metallicity SF region
  • NGC 346: open cluster in SMC
  • Orion Molecular Cloud Complex: group of molecular clouds with star-forming regions
  • Rho Ophiuchi Cloud Complex: nebula that is a nearby star-forming region
  • Serpens Cloud: molecular cloud with SF regions
  • star formation history: star formation rate as a function of time
  • Taurus Molecular Cloud 1: nearby star-forming region
  • Taurus-Auriga Complex: nearby star-forming region
  • Trapezium Cluster: open cluster of stars in Orion Nebula
  • W51: cloud complex radio source
• SFRD: see star formation rate
  • star formation history: star formation rate as a function of time
• SFRG: see radio galaxy
• SFU: see IRTS
• SGB: see subgiant
• SGB: see supergalactic coordinate system
• SGD: see Hitomi
• SGF (SpaceGuard Foundation): private organization to discover and track NEOs
• SGL: see natural astronomical telescopes
• SGL: see supergalactic coordinate system
• SGR (soft gamma repeater): object that produces repeated gamma-ray bursts
  • magnetar: neutron star with a strong magnetic field
• SGR 1935+2154: Milky Way SGR generating FRBs
• Sgr A* (Sag A*): SMBH at the center of Milky Way
• Sgr B2: GMC near the galactic center
• Sgr dE (Sagittarius Dwarf Elliptical Galaxy): satellite galaxy of the Milky Way
  • Milky Way subgroup: the Milky Way and its satellites
• Sgr dSph (Sagittarius Dwarf Elliptical Galaxy): satellite galaxy of the Milky Way
• SGR Dwarf (Sagittarius Dwarf Irregular Galaxy): most distant galaxy in the Local Group
• Sgr I Dwarf (Sagittarius Dwarf Elliptical Galaxy): satellite galaxy of the Milky Way
• SGR J1745-2900: magnetar orbiting the Milky Way SMBH
• SGRB (short gamma-ray burst): GRB lasting less than two seconds
• SGRB: see gamma-ray burst
  • GW170817: 2017 gravitational wave detection from a neutron star merger
  • long gamma-ray burst: GRB lasting more than two seconds
• SGRS: see rare designator prefixes
• SGW (Sloan Great Wall): large slab of galaxies discovered in SDSS
• Sh: see Herschel Double Star Catalog
• sh (shell star): type of star with broad and narrow absorption lines
• sh 2-276 (Barnard's Loop): emission nebula in Orion
• SH0ES: survey to increase the accuracy of the cosmic distance ladder
• Sh1: see Sharpless Catalog
• Sh2 (Sharpless Catalog): catalog of HII regions found on Palomar plates
• Shack-Hartmann sensor: see wavefront sensor
• Shajn: see rare designator prefixes
• Shakhbazian: see rare designator prefixes
• Shakura-Sunyaev disk (alpha disk): well-known model of an accretion disk
  • advection dominated accretion flow: accretion without radiating much energy
• ShAl: see rare designator prefixes
• shallow atmosphere models: see Juno
• shallow Mars-crosser: see Mars crosser
• SHAM: method of galaxy mock-catalog creation
• Shane Telescope: 3.05 m reflector telescope at Lick Observatory
  • coudé focus telescope: type of Nasmyth telescope with additional mirrors
  • CTIO Upper-Scorpius OB Association Survey: survey of low-mass stars and brown dwarfs
  • Lick Observatory: California observatory of long standing
• Shaped Antenna measurement of the background Radio Spectrum (SARAS): survey aiming at highly-redshifted 21-cm detection
• Shapiro delay: EMR delay due to passing near massive object
  • Einstein delay: EMR delay due to relativistic effects of environment and motion
• Shapiro time delay (Shapiro delay): EMR delay due to passing near massive object
• Shapley: see rare designator prefixes
• Shapley-Ames Catalog: 1932 catalog of contemporary data on 1249 galaxies
• Shapley-Ames Catalog of Bright Galaxies (Shapley-Ames Catalog): 1932 catalog of contemporary data on 1249 galaxies
• Shapley-Curtis Debate (Great Debate): historical debate regarding the nature of galaxies
• SHARAD: see Mars Reconnaissance Orbiter
• SHARC: see Caltech Submillimeter Observatory
• SHARC II: see Caltech Submillimeter Observatory
• SHARDS: GTC survey in GOODS-N field for quenched galaxies at z = 1 to 2.3
• SHARK: see Large Binocular Telescope
• SHARK-NIR: see Large Binocular Telescope
• SHARK-VIS: see Large Binocular Telescope
• SHARP: see Caltech Submillimeter Observatory
• Sharpless 103 (Cygnus Loop): supernova remnant in Cygnus
• Sharpless Catalog: catalog of HII regions found on Palomar plates
• SHB: see double star designation
• shearing box: method of simulating 3D MHD in disks
• SHeFI: see Atacama Pathfinder Experiment
• SHELA (Spitzer HETDEX Exploratory Large Area Survey): Spitzer-based survey of galaxies
• shell: hollow shaped region of some kind of ISM
• shell (electron shell): radius-level around an atomic nucleus at which electrons can orbit
• shell (mass shell): conceptual volume of mass shaped like a hollow sphere
  • Anticenter Shell: nebula at edge of Milky Way
  • electron orbital: a nucleus's "locations" where an electron can orbit
  • Local Bubble: ISM shell in which the solar system resides
  • supershell: very large ISM shell-shaped region
• shell flash: see helium flash
• shell galaxy: galaxy with one or more surrounding layers of brightness
• shell star: type of star with broad and narrow absorption lines
• shell-type remnant: see supernova remnant
• shepherd moon: small moon affecting outer edge of a planet's ring
• shepherding moon (shepherd moon): small moon affecting outer edge of a planet's ring
• Sher: see rare designator prefixes
• SHERLOC: see Mars 2020
• SHFI: see Atacama Pathfinder Experiment
• shielding effect: see electron screening
• shift-and-add: common speckle-suppression technique
  • speckle imaging: method of combining short-term images to yield better resolution
• SHJ: see Herschel Double Star Catalog
• Shk: see rare designator prefixes
• SHOC: see rare designator prefixes
• shock (shock wave): abrupt propagating disturbance in a fluid
  • blastwave: spherical shock wave from a small volume
  • bow shock: shock wave of a magnetosphere through the surrounding medium
  • high resolution shock capture: method of modeling shock waves
  • iSALE: code modeling the shock physics of impacts
  • silicon monoxide: compound of silicon and oxygen, one atom each
  • Tillotson equation: equation of state for high speed impacts
  • UCLCHEM: code to simulate the chemical reactions due to heat
• shock capture scheme
• high resolution shock capture: method of modeling shock waves
• shock front (shock wave): abrupt propagating disturbance in a fluid
• shock heating: see shock wave
• shock tracer: see shock wave
• shock wave: abrupt propagating disturbance in a fluid
• shooting star: see meteoroid
• short gamma-ray burst: GRB lasting less than two seconds
• short gamma-ray burst: see gamma-ray burst
  • long gamma-ray burst: GRB lasting more than two seconds
• short Rossby wave: see Kelvin waves
• short-period comet: see long-period comet
• shot noise (photon noise): variation in light measurement due to its quantum nature
• shot noise level: see photon noise
• showyourwork!: workflow software for reproducible research
• SHS: see SuperCOSMOS Sky Survey
• shudder speed (exposure time): time spent acquiring a signal
• Shuttle Pointed Autonomous Research Tool for Astronomy (SPARTAN): series of astronomy satellites launched/retrieved by Space Shuttles
• SI: standardized metric system
• SI: see sulfur
  • CGS: metric system variant
  • joule: SI unit of energy
  • kelvin: unit of temperature scale starting at absolute zero
  • magnetic flux: measure of magnetism passing through a surface
  • magnetic flux density: vector field describing magnetism in relation to the Lorentz force
  • mole: unit roughly the count of hydrogen atoms in a gram
  • siemens: SI unit of electrical conductance
  • tesla: unit of magnetic flux density
  • watt: SI unit of power
• Si (silicon): metal, Si, atomic number 14
• SID: see solar storm
• side lobe: see beam
  • CLEAN: algorithm to extract usable images from interferometry-produced images
  • dirty image: image that includes the distortions of the beam and sampling
• sidereal: relative to the fixed position of the stars
• sidereal day: see sidereal
  • solar day: length of a solar system planet or Moon's day
  • solar time: time based upon the position of the Sun in the Earth's sky
  • Venus: second inner-most planet in the solar system
• sidereal month: see sidereal
• sidereal orbital period: see sidereal
• sidereal period: see sidereal
  • orbital period: length of time for an orbiting object to complete one cycle
  • synodic period: period until a planet returns to the same position relative to the Sun
• sidereal rotation period: see rotation period
• sidereal rotation period: see sidereal
  • synodic period: period until a planet returns to the same position relative to the Sun
• sidereal time: see sidereal
  • solar time: time based upon the position of the Sun in the Earth's sky
• sidereal year: see sidereal
• siderophile: material that dissolves in molten iron
• siderophile element (siderophile): material that dissolves in molten iron
• Siding Spring 2.3 m Telescope (ANU 2.3m Telescope): 2.3-m telescope at Siding Spring Observatory
  • Siding Spring Observatory: observatory in New South Wales, Australia
• Siding Spring Observatory: observatory in New South Wales, Australia
  • Anglo-Australian Telescope: 3.9-m reflector telescope in Australia
  • GOTO: telescope array to follow up gravitational wave signals
  • Lupus Transit Survey: survey for hot Jupiters in a region of constellation Lupus
  • SkyMapper: automated 1.35 m optical telescope in Australia
  • UK Schmidt Telescope: 1.2 meter telescope in Australia with wide field-of-view
• siemens: SI unit of electrical conductance
• siemens per meter: see siemens
• SiFAP2: see Telescopio Nazionale Galileo
• SIFS: see SOAR Telescope
• SIFUS: see SOAR Telescope
• SIGHT: see Hale Telescope
• sight line (line of sight): line between observer and observed object
• SIGMA: see GRANAT
• sigma: indication of the confidence level of an experiment
• sigma-8: see sigma-8 tension
• sigma-8 tension: Lambda CDM anomaly regarding matter fluctuation
• Sigma-D relation: see Faber-Jackson relation
• signal
• biofluorescence: common fluorescence in organisms to dissipate harmful UV radiation
• biosignature: sign of life
• chirp: burst of signal rising or falling in frequency
• frequency modulation: changing the frequency of a signal's carrier
• geosignature: geological sign of consequences of life
• parts per million: method of expressing a small ratio
• red noise: noise tending toward lower frequencies
• technosignature: sign of technology
• vegetation red edge: wavelength cut-off point in the reflectivity of typical plants
• signal-to-noise: see signal-to-noise ratio
• signal-to-noise ratio: ratio of the power of a signal to the power of the background noise
• signature (spectral signature): spectral characteristics indicating the emitting material and conditions
• signatures of formation: qualities of a body that suggest how it was formed
• SII: see intensity interferometer
• SII: see sulfur
• silica
• basalt: an igneous rock type that shows rapid cooling
• geochemistry: the chemistry of the Earth, planets, and moons
• silicate: type of compound including silicon and oxygen
  • rocky planet: planet like Earth and Mars, mostly rock
• silicate weathering feedback: feedback mechanism stabilizing carbon in Earth atmosphere
• silicon: metal, Si, atomic number 14
  • carbonate-silicate cycle: long-term cycle that sequesters Earth carbon
  • oxygen burning: fusion reaction starting with oxygen
  • silicate weathering feedback: feedback mechanism stabilizing carbon in Earth atmosphere
  • silicon burning: alpha process fusion starting at silicon
  • silicon monoxide: compound of silicon and oxygen, one atom each
• silicon burning: alpha process fusion starting at silicon
  • nucleosynthesis: creation of atomic nuclei
  • silicon: metal, Si, atomic number 14
• silicon dioxide
• carbonate-silicate cycle: long-term cycle that sequesters Earth carbon
• silicate weathering feedback: feedback mechanism stabilizing carbon in Earth atmosphere
• silicon monoxide: compound of silicon and oxygen, one atom each
• silicon-burning shell: see silicon burning
• Silk damping (diffusion damping): a damping process within the plasma during recombination
• Silver Coin Galaxy (NGC 253): spiral galaxy 11 million light-years away
• Silver Dollar Galaxy (NGC 253): spiral galaxy 11 million light-years away
• SIM (Space Interferometry Mission): past space interferometer plan for parallax and exoplanet detection
• SIM: see Chandra X-ray Observatory
• SIMBA: galaxy formation simulation code
• SIMBA: see Swedish-ESO Submillimetre Telescope
• Simba (SIMBA): galaxy formation simulation code
• SIMBAD: online database of astronomical objects
  • Centre de données astronomiques de Strasbourg: repository of astronomical data
• Simeis: see rare designator prefixes
• Simons Array: telescope array to map CMB polarization
  • Simons Observatory: CMB observatory on Atacama Desert
• Simons Observatory: CMB observatory on Atacama Desert
  • Simons Array: telescope array to map CMB polarization
• SIMP: 2000s infrared proper-motion survey
• SIMPLE: see European Extremely Large Telescope
• simple Bouguer correction: see Bouguer anomaly
• simple Bouguer reduction: see Bouguer anomaly
• simple crater: see complex crater
• simple stellar population (SSP): set of stars born at the same time with the same metallicity
  • A-LIST: catalog of templates of H-band spectra for SPS
• simplex
• areal coordinate system: coordinate system based upon a known triangle
• Simplified Arbitrary Lagrangian Eulerian: see iSALE
• SIMSTACK: software to correlate intensity maps with sources
• simulation
• AREPO: cosmology simulation using moving mesh technique
• ARTEMIS: simulations of Milky-Way-like galaxy halos
• Astrid simulation: cosmological simulation over z = 99 to 3
• AstroBEAR: MHD simulation system
• Bolshoi simulation: cosmological simulation
• Castro: hydrodynamics simulation software
• ChaNGa: cosmological-simulation project active since circa 2015
• Cloudy: code to model the effect of gas and plasma on spectra
• CMFGEN: RT code designed to handle significant stellar wind
• Copernicus Complexio: high-resolution cosmological N-body simulation
• EAGLE: simulation of galaxy formation and evolution
• Enzo: hydrodynamic simulation system
• FIRE Simulations: high resolution simulation of galaxies
• FLASH: hydrodynamic simulation system
• FORNAX: hydrodynamics simulation software
• GADGET-2: an n-body/SPH simulation computer program
• Gasoline: an SPH code
• GERLUMPH: hardware/software simulator of lensing light curves
• GR1D: core collapse supernova simulation in 1D with GR
• Hyperion: Monte Carlo radiative transfer code
• Illustris Project: 2013-2015 series of cosmological simulations
• LA-COMPASS: MHD-capable hydrodynamic code
• MOCCA: code to model the evolution of stellar clusters
• PLUTO Code: fluid-dynamic simulation code
• PROMETHEUS/VERTEX: hydrodynamic simulation system
• RADEX: radiative transfer code
• RAMSES: hydrodynamic simulation system
• RHAPSODY: simulation of galaxy cluster dark-matter halos
• Romulus simulations: cosmological-simulation project active since circa 2015
• STARBURST99: software to simulate star-forming galaxies
• STARFORGE: star formation simulation code
• Turtlebeach: radiative transfer code
• simulations
• ADDGALS: method of galaxy mock-catalog creation
• computational astrophysics: astrophysical study through computer modeling
• cosmological zoom simulation: cosmological simulation plus higher resolution simulations of selected space
• HOD: model of galaxy distribution
• Monte Carlo method: mathematics and simulation using random samples
• N-body simulation: simulation of many objects gravitationally-bound to each other
• random walk: movement with random turns
• semi-analytic model: cosmological model combining analytic and other methods
• SHAM: method of galaxy mock-catalog creation
• simultaneity: see relativity
• Simultaneous Quad Infrared Imaging Device: NOAO instrument imaging in four infrared bands at once
• SINFONI: see European Southern Observatory Very Large Telescope
  • SINS: near-infrared study of distant luminous galaxies
• SINGG (The Survey for Ionization in Neutral Gas Galaxies): survey of HI in galaxies found through the H-alpha line
• single degenerate model: see Type Ia supernova problem
• single degenerate model: see supernova progenitor
  • Type Ia supernova: type of supernova for which distance can be determined
• Single Star Evolution: see BSE
• single stellar population (SSP): set of stars born at the same time with the same metallicity
• single-line spectroscopic binary: see double-line spectroscopic binary
• single-line spectroscopic binary: see spectroscopic binary
• single-metallicity stellar population (SSP): set of stars born at the same time with the same metallicity
• single-object slitless spectroscopy: see James Webb Space Telescope
• single-photon avalanche diode (Geiger-avalanche photodiode): type of solid state photon sensor
• single-strand DNA (ssDNA): DNA without the double strand
• singly ionized carbon (C⁺): ionized carbon missing one electron
• SINGS: see Spitzer Space Telescope
• singular perturbation problem: see perturbation theory
• singularity (gravitational singularity): point where density and gravity reach infinity
  • black hole: region of such high mass that light cannot escape
• SINS: near-infrared study of distant luminous galaxies
• SINS/zC-SINF
• SINS: near-infrared study of distant luminous galaxies
• Sinstro: see Las Cumbres Observatory
• SiO (silicon monoxide): compound of silicon and oxygen, one atom each
• SIPS: see rare designator prefixes
• SIR: see SMART-1
• Sirene 2: see Kvant 1
• SIRIUS: see Infrared Survey Facility
• Sirius: brightest star in the sky
  • Am star: A-type star with metallic lines
• Sirius A: see Sirius
• Sirius B: see Sirius
• SIRTF (Spitzer Space Telescope): retired infrared space telescope
• SIS: see ASCA
• SIS: see Advanced Composition Explorer
• SIS: see superconducting tunnel junction
  • Atacama Pathfinder Experiment: 12-meter submillimeter telescope in Chile
• site
• AAS Job Register: directory of astrophysics jobs
• ARIBIB: online astronomy/astrophysics bibliography
• arXiv: website with physics paper preprints
• AstroBetter: site with shared research tips.
• AstroBetter Rumor Mill: list of open astrophysics jobs
• Astrobites: online informal summaries of astrophysics papers
• Astronomy Picture of the Day: NASA general education initiative
• Astrophysics Data System: online astrophysics bibliography and paper archive
• Canadian Astronomy Data Centre: online data distribution
• Disk Detective: Zooniverse effort to find planets within protoplanetary disks
• EAS Job Directory: directory of astrophysics jobs
• ExoFOP: site to facilitate exoplanet follow-up observation
• Galaxy Zoo: crowdsourcing website to identify galaxy types from surveys
• Galaxy Zoo 2: crowd-sourced classification of hundreds of thousands of galaxies
• GitHub: online software development repositories
• HEASARC: NASA archive of data on high energy astronomy
• Hubble Asteroid Hunter: Zooniverse effort to find asteroids in HST images
• IRSA: archive center for infrared data from NASA missions
• LAMBDA: NASA archive center re CMB data
• Latest Supernovae: recent supernova info collected
• Level 5: hyperlinked collection of astrophysics research findings
• MAST: archive of data from surveys and missions
• NASA Exoplanet Archive: online database of exoplanets
• NASA/IPAC Extragalactic Database: a database of galaxies and other objects outside the Milky Way
• NEODyS: web service to providing information on NEOs
• Planet Hunters: crowdsourcing website to identify galaxy types from surveys
• RAS JobList: directory of astrophysics jobs
• SIMBAD: online database of astronomical objects
• Stelle Doppie: online database of double stars
• VisieR: online astronomical catalog contents/data
• Zenodo: online repository for making research data available
• Zooniverse: effort supporting research through crowdsourcing
• Site 300
• Livermore Optical Transient Imaging System: automated telescope aiming to catch GRB optical counterparts
• SITELLE: see Canada-France-Hawaii Telescope
  • imaging Fourier transform spectroscopy: Michelson-interferometer-based imaging spectroscopy
• Siv: see rare designator prefixes
• Six-Degree Field Galaxy Survey (6dF Galaxy Survey): UKST survey of galaxies in the southern sky
• Sk: see rare designator prefixes
• SKA (Square Kilometre Array): planned radio telescope with square-kilometer collecting area
• SKA I-low: see Square Kilometre Array
• SKA I-mid: see Square Kilometre Array
• SKA Pathfinder: see Square Kilometre Array
• SKA Precursor: see Square Kilometre Array
• SKA-AAMID: see Square Kilometre Array
• SKA-LOW: see Square Kilometre Array
• SKA-MID: see Square Kilometre Array
• SKA1: see Square Kilometre Array
• SKA1-low: see Square Kilometre Array
• SKA1-mid: see Square Kilometre Array
• SKA2: see Square Kilometre Array
• SKAO (Square Kilometre Array): planned radio telescope with square-kilometer collecting area
• SKBO
• trans-Neptune object: minor planet beyond Neptune
• skeleton
• filament: linear volume of high molecular gas density within a galaxy
• SKHB: survey of globular clusters in M31
• SKI: see double star designation
• Skumanich law: see gyrochronology
• Skumanich relationship: see gyrochronology
• sky: see celestial sphere
  • Baade's Window: region of sky allowing observation into the galactic center
  • BDF: field used in search for distant galaxies
  • Extended Groth Strip: region of sky searched for distant galaxies
  • Gould's Belt: ring of stars around the sky
  • Groth Strip: region of sky in early HST survey
  • Lockman hole: region of sky with little Milky-Way neutral hydrogen
  • Olbers' paradox: argument using the dark of the sky regarding the nature of the universe
  • plane of the sky: plane tangent to the celestial sphere
  • sidereal: relative to the fixed position of the stars
  • zone of avoidance: region of sky obscured by Milky Way
• Sky & Telescope: amateur astronomy publication
• sky localization (localization): ability to identify location of a transient
• sky quality meter: device to measure the brightness/magnitude of the sky itself.
• sky subtraction: removing background radiation from a telescope observation
• SkyCam: see Liverpool Telescope
• Skylab
• International Space Station: long-term manned space station operated by numerous nations
• SkyMapper: automated 1.35 m optical telescope in Australia
  • Siding Spring Observatory: observatory in New South Wales, Australia
  • SkyMapper Southern Survey: digital survey of the southern hemisphere sky
• SkyMapper Southern Sky Survey (SkyMapper Southern Survey): digital survey of the southern hemisphere sky
• SkyMapper Southern Survey: digital survey of the southern hemisphere sky
• SL (Spacelab): reusable laboratory that was an optional Space Shuttle payload
• SL: see rare designator prefixes
• SLED (spectral line energy distribution): function or plot of brightness of lines in a spectrum
  • carbon monoxide: compound of carbon and oxygen, one atom each
• Slepian window function: see window function
• slew: rotating a telescope to point it
  • slew survey: survey conducted by imaging during a telescope's repointings
• slew angle: see slew
• slew observation: see slew survey
• slew speed: see slew
• slew survey: survey conducted by imaging during a telescope's repointings
  • commensal mode: telescope usage that accomplishes multiple observations simultaneously
• slew time: see slew
• SLF (super low frequency): electromagnetic radiation, frequency 30 Hz to 300 Hz
• slide rule: see numerical methods
• SLIM: see XRISM
• slim disk: see AGN accretion
• slingshot (gravity assist): method of boosting the speed of a spacecraft
• slit
• fiber positioner: machine to set up fibers in multi-object spectrograph
• integral field spectrograph: spectrograph that captures images
• slitless spectrograph: spectrograph that does not utilize a slit
• slitless spectrograph: see multi-object spectrograph
  • Rapid Eye Mount Telescope: quick-action robotic telescope at La Silla Observatory
• slitless spectrography: see slitless spectrograph
• slitless spectroscopy: see multi-object spectrograph
• Sloan 2.5m Telescope: telescope for SDSS in New Mexico
  • APOGEE: SDSS near-infrared survey of stars
  • Sloan Digital Sky Survey: imaging survey of 500,000,000 objects in 35% of sky
• Sloan Digital Sky Survey: imaging survey of 500,000,000 objects in 35% of sky
• Sloan Digital Sky Survey V
• Milky Way Mapper: SDSS spectrographic survey of Milky Way stars
• Sloan Extended Quasar, ELG, and LRG Survey: see Baryon Oscillation Spectroscopic Survey
• Sloan Extension for Galactic Understanding and Exploration: see Sloan Digital Sky Survey
• Sloan Foundation 2.5m Telescope (Sloan 2.5m Telescope): telescope for SDSS in New Mexico
• Sloan Great Wall: large slab of galaxies discovered in SDSS
• Sloan Supernova Survey: see supernova survey
• SLOTIS: see Livermore Optical Transient Imaging System
• slow irregular variable: see pulsating star
• slow neutron-capture process (s-process): synthesis of elements through neutron capture and beta decay
  • r-process: synthesis of elements through neutron capture faster than beta decay
• slow quenching: see quenched galaxy
• slow shock: see shock wave
• slowly-pulsating B-star: B-star with pulsation periods of more than half a day
• SLR: see double star designation
• SLS (Space Launch System): launch rocket in development, e.g., for future astronomical projects
• SLS: see SPIRou
  • Origins Space Telescope: concept for 2030s large space IR telescope
• SLSN (superluminous supernova): stellar explosion larger than a supernova
• SLSN-I: see superluminous supernova
• SLSN-II: see superluminous supernova
• SLSN-R: see superluminous supernova
• SLX: see rare designator prefixes
• SM: see SkyMapper Southern Survey
• Sm: see rare designator prefixes
• SM0313
• SkyMapper Southern Survey: digital survey of the southern hemisphere sky
• SMA (Submillimeter Array): radio interferometer in Hawaii
• SMA: see double star designation
  • East Asian Observatory: operator of JCMT
  • Mauna Kea: Hawaiian mountain, the site of observatories
  • Mauna Kea Observatories: observatories on Mauna Kea in Hawaii
  • Millimeter-wave Intensity Mapping Experiment: project to map CO and [CII]
• SMACS: see Massive Cluster Survey
• Small Aperture Telescope: see Simons Observatory
• Small Astronomical Satellite 1 (Uhuru): 1970 X-ray space telescope
• Small Astronomical Satellite program
• Small Astronomy Satellite 2: 1970s NASA gamma ray space telescope
• Small Astronomy Satellite 3: 1970s NASA X-ray space telescope
• Uhuru: 1970 X-ray space telescope
• Small Astronomy Satellite 2: 1970s NASA gamma ray space telescope
• Small Astronomy Satellite 3: 1970s NASA X-ray space telescope
• Small Bodies Names Committee: old name of IAU Committee for Small Body Nomenclature
• small body (SSSB): solar system body smaller than a dwarf planet
• Small Explorer Program: NASA program for small science spacecraft
  • Galaxy Evolution Explorer: observatory-satellite with 50-cm ultraviolet telescope
  • Interstellar Boundary Explorer: satellite observing the ISM/heliosphere boundary
  • IXPE: space observatory with X-ray polarimeters
  • NASA: includes space-based astronomy research
  • NuSTAR: space telescope for high-energy X-rays
  • PUNCH: 4 microsatellites to observe the Sun
  • TRACE: former solar observing satellite
  • Wide Field Infrared Explorer: partly-failed 1999 infrared satellite
• Small Explorers
• NASA: includes space-based astronomy research
• Small IRAIT: see Infrared Telescope Maffei
• Small Magellanic Cloud: dwarf galaxy in the Local Group
  • Catalog of Azzopardi & Vigneau: probable stars in the SMC
  • Milky Way subgroup: the Milky Way and its satellites
• Small Missions for Advanced Research in Technology-1 (SMART-1): Swedish lunar orbiter operational 2003-2006
• small satellite: NASA term for a satellite of 1200 kg or less
• small solar system bodies
• solar system object: the Sun, solar system planets, minor planets, comets, and moons
• small solar system body (SSSB): solar system body smaller than a dwarf planet
  • minor planet: lesser solar system body without comet characteristics
• Small-Sized Telescope: see Cherenkov Telescope Array
• smallsat (small satellite): NASA term for a satellite of 1200 kg or less
• Smart Lander for Investigating Moon: see XRISM
• SMART-1: Swedish lunar orbiter operational 2003-2006
• SMBBH (binary SMBH): co-orbiting supermassive black holes
  • supermassive black hole: black hole with a mass of millions to billions of solar masses
• SMBH (supermassive black hole): black hole with a mass of millions to billions of solar masses
  • binary SMBH: co-orbiting supermassive black holes
  • black hole: region of such high mass that light cannot escape
  • black hole accretion rate: measure, especially used for AGNs
  • BlackHoleCam: European project to study black holes
  • NGC 1600: elliptical galaxy with large supermassive black hole
  • reverberation mapping: technique for measuring the size of SMBHs
  • Romulus simulations: cosmological-simulation project active since circa 2015
  • Soltan argument: distant quasars imply SMBHs still exist
• SMBH binary (binary SMBH): co-orbiting supermassive black holes
• SMBH formation: process by which SMBHs form
• SMBHB (binary SMBH): co-orbiting supermassive black holes
  • supermassive black hole: black hole with a mass of millions to billions of solar masses
• SMC (Small Magellanic Cloud): dwarf galaxy in the Local Group
• SMC: see rare designator prefixes
  • Catalog of Azzopardi & Vigneau: probable stars in the SMC
  • DeGaS-MC: APEX survey of potential star formation regions in the Magellanic Clouds
  • EROS: search for MACHOs
  • MACHO Project: survey searching out microlensing that could indicate a MACHO
  • Magellanic Catalogue of Stars: 1980s/1990s survey of stars in Magellanic Clouds
  • Magellanic Clouds Photometric Survey: UBVI survey of the Magellanic Clouds
  • Milky Way subgroup: the Milky Way and its satellites
  • NGC 346: open cluster in SMC
  • Radcliffe Observatory Magellanic Clouds Catalogue: catalog of stars in
  • SAGE: survey of gas and dust in the Magellanic Clouds
  • SMC X-1: high-mass X-ray binary with X-ray pulsar
• SMC AB: see rare designator prefixes
• SMC X-1: high-mass X-ray binary with X-ray pulsar
• SMC-N: see rare designator prefixes
• SME (Solar Mesophere Explorer): 1980s Earth atmospheric ozone research satellite
• Smethells: see rare designator prefixes
• SMEX (Small Explorer Program): NASA program for small science spacecraft
  • Galaxy Evolution Explorer: observatory-satellite with 50-cm ultraviolet telescope
  • Interstellar Boundary Explorer: satellite observing the ISM/heliosphere boundary
  • IXPE: space observatory with X-ray polarimeters
  • NASA: includes space-based astronomy research
  • NuSTAR: space telescope for high-energy X-rays
  • PUNCH: 4 microsatellites to observe the Sun
  • TRACE: former solar observing satellite
  • Wide Field Infrared Explorer: partly-failed 1999 infrared satellite
• SMEX 15 (PUNCH): 4 microsatellites to observe the Sun
• SMG (submillimeter galaxy): galaxy that produces significant submillimeter radiation
  • AMUSE²: survey of ELANs
  • luminous infrared galaxy: a galaxy emitting a lot of far-infrared light
• SMI: see SPICA
• SMI-HRS: see SPICA
• SMI-LRS: see SPICA
• SMI-MRS: see SPICA
• Smith Cloud: high-velocity cloud on collision course with Milky Way
  • high-velocity cloud: fast-moving clouds in galactic halos
• Smith's Cloud (Smith Cloud): high-velocity cloud on collision course with Milky Way
• Smithsonian Astrophysical Observatory: see Center for Astrophysics
  • Astrophysics Data System: online astrophysics bibliography and paper archive
  • CfA Redshift Survey: 1970s-1990s surveys of galaxy redshifts
  • Fred Lawrence Whipple Observatory: observatory near Amado, Arizona
  • SAO Star Catalog: 1960s catalog
• Smithsonian Astrophysical Observatory Star Catalog (SAO Star Catalog): 1960s catalog
• Smithsonian Institute
• Center for Astrophysics: Harvard and Smithsonian research and education organization
• SMM (Solar Maximum Mission): 1980s satellite to study the Sun during solar maximum
• SMM: see submillimeter galaxy designator
• SMNS: see hypermassive neutron star
• smoking gun: convincing piece of evidence
• smooth migration: see planetary migration
• smoothed-particle hydrodynamics: computational method for simulating fluid flows
  • Gasoline: an SPH code
• SMP: see Hayabusa2
• SMP: see rare designator prefixes
• SMS (supermassive star): star more massive than stars normally form
• SMSS (SkyMapper Southern Survey): digital survey of the southern hemisphere sky
• SMSS 2003-1142 (SMSS J2003-1142): unusual giant star in Milky Way halo
• SMSS J2003-1142: unusual giant star in Milky Way halo
• SMT (Submillimeter Telescope): 10-meter far-infrared telescope
• smuon: see supersymmetry
• SMY: see double star designation
• SN (supernova): stellar explosion larger than a nova
• SN: see signal-to-noise ratio
• SN 1054: see Crab Nebula
  • electron capture supernova: supernova from collapse of iron-free stellar cores
• SN 1572: Type Ia supernova noted in 1572 by Tycho Brahe
  • Cassiopeia A: supernova remnant visible for 300 years
• SN 1604 (Kepler's Supernova): Type Ia supernova observed in 1604 by Johannes Kepler
  • Cassiopeia A: supernova remnant visible for 300 years
• SN 1667: see Cassiopeia A
• SN 1671: see Cassiopeia A
• SN 1680: see Cassiopeia A
• SN 185: supernova recorded in China in AD 185
• SN 1972E
• SN 2014J: Type Ia supernova in Messier 82, the Cigar Galaxy
• SN 1987A: supernova in February 1987 rare for being visible by the naked eye
  • 30 Doradus: HI region in LMC
• SN 1998bw: 1998 supernova with a coincident GRB
  • GRB-supernova: supernova that produces a GRB
• SN 2011fe: see Pinwheel Galaxy
• SN 2014dj
• SN 2014J: Type Ia supernova in Messier 82, the Cigar Galaxy
• SN 2014J: Type Ia supernova in Messier 82, the Cigar Galaxy
• SN 2018cow (AT2018cow): unusual 2018 optical transient
• SN 2018zd
• electron capture supernova: supernova from collapse of iron-free stellar cores
• SN 2019fdr: see AT2019dsg
• SN 2020eyj
• radio supernova: supernova that includes a detectable radio emission
• SN 2023af: see International Liquid Mirror Telescope
• SN feedback: see star formation feedback
• SN Hubble diagram: see Hubble diagram
• SN impostor (supernova impostor): extreme stellar explosion that does not destroy the star
• SN light curve (supernova light curve): changing intensity of light following a supernova
• SN progenitor (supernova progenitor): the star or star system that produces a supernova
  • Type Ia supernova problem: lack of fully-convincing Type Ia supernovae triggering model
• SN remnant (supernova remnant): nebula of debris resulting from a supernova
• SN-GRB (GRB-supernova): supernova that produces a GRB
• SNAP (Snapshot Program): short HST observation program aimed to fit between more substantial programs
  • Roman Space Telescope: proposed near-infrared space observatory
• Snapshot Program: short HST observation program aimed to fit between more substantial programs
• SNDM
• nebular hypothesis: model positing solar system planets result from a solar disk
• Snell's law: optical principle of refraction
  • refraction: redirection of light passing from one medium to another
  • refractive index: measure of how much a material slows down light
• Snell-Descartes law (Snell's law): optical principle of refraction
• sneutrino: see supersymmetry
• SNEWS: see supernova survey
• SNF: see Nearby Supernova Factory
• SNfactory (Nearby Supernova Factory): survey that scanned transient data for supernovae
• SNLS (Supernova Legacy Survey): detect and monitor supernovae to measure the effects of dark energy
• SNO (Sudbury Neutrino Observatory): Canadian underground neutrino detector
• SNO: see SPECULOOS
• SNO+: see Sudbury Neutrino Observatory
• SNOLAB: see PICO experiment
  • Cryogenic Dark Matter Search: a search for a candidate dark matter particle
  • Cryogenic Rare Event Search with Superconducting Thermometers: a search for a candidate dark matter particle
• snow line: distance from protostar so cool that water condenses
  • ice: solid state of water
• Snow Solar Tower: see Mount Wilson Observatory
• Snowmass: initiative recommending the next decade's particle physics strategy
• snowplow phase: see supernova remnant
• SNR (signal-to-noise ratio): ratio of the power of a signal to the power of the background noise
• SNR (supernova remnant): nebula of debris resulting from a supernova
• SNR 3C 397 (3C 397): supernova remnant discovered as a radio source
• SNR G111.7-02.1 (Cassiopeia A): supernova remnant visible for 300 years
• SNR G184.6-05.8 (Crab Nebula): supernova remnant in Taurus
• SNR G260.4-03.4 (Puppis A): supernova remnant bright in X-ray
• SNR G263.9-03.3 (Vela supernova remnant): nearby supernova remnant
• SNR G276.5+19.0 (Antlia SN Remnant): dispersed supernova remnant in the constellation Antlia
• SNR G315.0-02.3: see SN 185
• SNT (Schmidt-Newton telescope): type of reflector telescope
  • Schmidt camera: telescope type with a very wide field of view
• SNU (solar neutrino unit): unit for the detection rate of neutrino detectors
  • solar neutrino: neutrino from the Sun
• SO (Simons Observatory): CMB observatory on Atacama Desert
• SO: see rare designator prefixes
• SO₂
• Venus: second inner-most planet in the solar system
• SOAR (SOAR Telescope): 4.1 m reflector telescope in Chile
  • Cerro Tololo Inter-American Observatory: NOIRLab observatory in Chile with Blanco telescope
  • RESOLVE­: galaxy and gas survey limited to 65-100 Mpc
• SOAR Telescope: 4.1 m reflector telescope in Chile
• SOARD (Steward Observatory Asteroid Relational Database): 1980s/1990s repository of asteroid data
• Sobolev approximation: tractable model used in specific kinds of spectral line analysis
• Sobolev length: see Sobolev approximation
• Société astronomique de France: French non-profit astronomical society
• Sociedad Astronómica de Valparaíso y Viña del Mar: Chilean amateur astronomy society
• Society of Amateur Radio Astronomers: US organization
• SODART: see Spektr-RG
• sodium: metal, Na, atomic number 11
  • globular cluster: spherical group of stars orbiting a galaxy
  • nitrite: ion of a nitrogen atom and two oxygen atoms with extra electron
• sodium hydroxide
• hydroxyl: one hydrogen atom and one oxygen atom bound together
• sodium lamp
• light pollution: light from cities that interferes with astronomical observation
• sodium nitrite: see nitrite
• SOFI: see New Technology Telescope
  • PESSTO: NTT survey following up on transients
• SOFIA: aircraft-based infrared observatory
• soft
• Heggie-Hills law: hard binary stars generally get harder when encountering a third star
• soft binary: see hardness
• soft EoS: see equation of state
• soft gamma repeater: object that produces repeated gamma-ray bursts
• soft gamma-ray repeater
• magnetar: neutron star with a strong magnetic field
• soft X-ray: see X-ray
  • XEUV: electromagnetic radiation in the range of 0.15-124 nm
• soft X-ray and extreme ultraviolet (XEUV): electromagnetic radiation in the range of 0.15-124 nm
• Soft X-ray Background Radiation Investigation: see OSO 8
• soft X-ray source: see X-ray source
• soft X-ray transient: see transient
• softness: see hardness
• software
• ADAM: procedure to retrieve the shape of an asteroid
• ADAM::THOR: computerized system for discovering asteroids in observation data
• AREPO: cosmology simulation using moving mesh technique
• Astrid simulation: cosmological simulation over z = 99 to 3
• AstroBEAR: MHD simulation system
• Astrocats: software to create and manage an astronomy catalog
• Astronomical Image Processing System: software for processing radio astronomy data
• Astrophysics Multi-spectral Archive Search Engine: 1990s search tool
• astropy: general Python package for astrophysical research
• ATLAS Stellar Model: computer model of a stellar photosphere
• Bolshoi simulation: cosmological simulation
• BT-Settl: model atmosphere of small stars and brown dwarfs
• CASA: software package for radio interferometry image generation
• Castro: hydrodynamics simulation software
• Chandra Interactive Analysis of Observations: software for analyzing Chandra X-ray data
• ChaNGa: cosmological-simulation project active since circa 2015
• CMBFAST: software to calculate CMB anisotropies
• CMFGEN: RT code designed to handle significant stellar wind
• code: astrophysical modeling computer program
• COMPAS: SPS code for compact object binaries
• corner.py: Python library for scatter plot matrices
• DAOPHOT: 1980s CCD photometry software
• DISORT: simulation of radiative transfer in an atmosphere
• dynesty: code for comparing the applicability of multiple models
• EAGLE: simulation of galaxy formation and evolution
• Enzo: hydrodynamic simulation system
• ExoCTK: collection of software for exoplanet observation and analysis
• FIRE Simulations: high resolution simulation of galaxies
• FLASH: hydrodynamic simulation system
• FORNAX: hydrodynamics simulation software
• GADGET-2: an n-body/SPH simulation computer program
• GaiaHub: software to extract proper motions form Gaia and HST data
• Gala: galaxy-formation and evolution software package
• GALLUMI: automated cosmological analysis software
• Gasoline: an SPH code
• GitHub: online software development repositories
• Glue: visualization software good for astrophysical data
• GR1D: core collapse supernova simulation in 1D with GR
• Guide Star Astrometric Support Package: software to assist in using guide stars for HST observations
• HEALPix: type of map projection for spheres
• Hyperion: Monte Carlo radiative transfer code
• IDL: interactive vector-oriented programming language
• Illustris Project: 2013-2015 series of cosmological simulations
• Image Reduction and Analysis Facility: NOAO-developed image manipulation/viewing software
• Jupyter: notebook-style programming interface used with Python
• JWST ETC: Python-based exposure time calculator for JWST
• LA-COMPASS: MHD-capable hydrodynamic code
• LasDamas: simulations of large scale evolution of dark matter and galaxies
• lightkurve: software to analyze time series data
• Matplotlib: Python library for plotting
• MESA: collection of stellar astrophysics code
• MITgcm: well-known general circulation model
• mlmapper: software for maximum-likelihood mapmaking
• MOSFiT: code to match light-curves with light-curve models
• NumPy: Python library for numerical programming with arrays
• OpenSpace: visualization software aimed at astrophysical data
• orbitize: planet orbit-fitting software for direct image observations
• Partiview: visualization software aimed at 4D data
• Period04: software to identify periods in time series data
• PHOENIX stellar model: computer model of a stellar photosphere
• PLUTO Code: fluid-dynamic simulation code
• PROMETHEUS/VERTEX: hydrodynamic simulation system
• PyMC: Python package for Bayesian statistical modeling
• RADEX: radiative transfer code
• RAMSES: hydrodynamic simulation system
• RASCALL: efficient code to locate suspected molecular lines
• RHAPSODY: simulation of galaxy cluster dark-matter halos
• ROCKE-3D: rocky-planet-oriented general circulation model
• SciPy: Python library for scientific programming
• showyourwork!: workflow software for reproducible research
• SIMBA: galaxy formation simulation code
• SIMSTACK: software to correlate intensity maps with sources
• Space Telescope Science Data Analysis System: software designed for analysis of HST data
• SPECTRE: an interactive spectrum analysis software package
• STARBURST99: software to simulate star-forming galaxies
• StarTrack: stellar population synthesis code
• SWMF: software package of tools for modeling space weather
• TAM: non-gray-RT 3D model of Titan's atmosphere
• Turtlebeach: radiative transfer code
• U-Net: neural network software for image reconstruction
• Uniview: planetarium software
• WSA-Enlil: computer model of heliosphere for space weather prediction
• XGBoost: machine learning software
• XMM-Newton Science Analysis System: software designed to analyze XMM-Newton X-ray data
• yt: analysis and display software
• software telescope: telescope that depends more than normal upon software for analysis
• software type
• adaptive mesh refinement: numerical modeling method balancing detail with tractability
• convolutional neural network: type of image processing software
• exposure time calculator: app to calculate time to carry out an observation
• N-body simulation: simulation of many objects gravitationally-bound to each other
• radiative transfer code: computer model of a gas's radiative transfer
• radiative transfer model: models of radiative transfer, often computerized
• semi-analytic model: cosmological model combining analytic and other methods
• stellar population synthesis code: software to perform stellar population synthesis
• SOHO (Solar and Heliospheric Observatory): satellite observing the Sun
• SOI: see SOAR Telescope
• SOIRDETE: see GI2T
  • optical interferometer: interferometer of visible light
• Sojourner: see Mars Pathfinder
• Sol: see Mars
• Sol: see solar day
• solar
• 1947 sunspot: largest sunspot ever recorded
• 775 AD event: apparent solar eruption, based upon tree-ring evidence
• ACES: a spectrometer used to view the corona during eclipses
• Advanced Composition Explorer: satellite collecting solar wind and cosmic rays
• Air-SPEC: a spectrometer used to view the corona during eclipses
• Carrington event: solar storm September 1-3 1859
• Coronal Solar Magnetism Observatory: proposed solar observatory
• DISCOVR: space weather satellite
• DKIST: 4 m solar telescope at Haleakala Observatory
• ESA Vigil: plan for space-weather warning satellite at L5
• heliosphere: region of space dominated by the Sun
• High Altitude Observatory: NCAR unit observing and monitoring the Sun
• IMAP: future solar science probe
• Mauna Loa Solar Observatory: solar observatory on Mauna Loa
• OSO 7: 1970s observatory-satellite for viewing the Sun
• OSO 8: 1970s observatory-satellite for viewing the Sun
• PUNCH: 4 microsatellites to observe the Sun
• Solar and Heliospheric Observatory: satellite observing the Sun
• Solar Dynamics Observatory: 2010 satellite observing the Sun
• Solar Maximum Mission: 1980s satellite to study the Sun during solar maximum
• STEREO: two-satellite system to observe the Sun
• SWFO-L1: future NOAA space-weather warning satellite
• SWMF: software package of tools for modeling space weather
• TRACE: former solar observing satellite
• WSA-Enlil: computer model of heliosphere for space weather prediction
• Yohkoh: 1990s Japanese solar observatory spacecraft
• solar activity: see stellar activity
• Solar and Heliospheric Observatory: satellite observing the Sun
• solar antapex: see solar apex
• solar apex: direction that the Sun is moving compared to nearby stars
• solar arcade (magnetic arcade): series of arch-like magnetic flux lines on the Sun
• solar atmosphere: see stellar atmosphere
• solar cell
• photodiode: class of solid state device to detect EMR
• solar circle: Sun's orbit around the Milky Way
• solar constant: flux from the Sun at 1 AU
• solar core: see stellar core
• solar corona: see corona
• solar cosmic rays: see solar energetic particle
• solar cycle: see sunspot
• solar day: length of a solar system planet or Moon's day
  • solar time: time based upon the position of the Sun in the Earth's sky
  • synodic period: period until a planet returns to the same position relative to the Sun
  • Venus: second inner-most planet in the solar system
• Solar Dynamics Observatory: 2010 satellite observing the Sun
• solar dynamo: see dynamo
• solar eclipse: eclipse consisting of the Moon blocking the Sun from view
  • celestial event: something astronomical occurring visibly in the sky
• solar energetic particle: high-energy particles from the Sun
  • solar particle event: episode of higher velocity solar wind
  • UVSC Pathfinder: instrument to observe the Sun
• solar energetic particle event (solar particle event): episode of higher velocity solar wind
• solar eruption: sudden brightening of the Sun
  • solar flare: sudden brightening of the Sun
  • solar storm: general term for events on the Sun
  • space weather: varying conditions in space affecting Earth and humans
  • Sun surface features: features on the Sun's surface
• solar event (solar storm): general term for events on the Sun
• solar flare: sudden brightening of the Sun
  • solar eruption: sudden brightening of the Sun
  • solar storm: general term for events on the Sun
  • space weather: varying conditions in space affecting Earth and humans
  • stellar flare: sudden brightening of a star
  • Sun surface features: features on the Sun's surface
• solar galactocentric distance: see solar circle
• solar gravitational lens: see natural astronomical telescopes
• Solar Influences Data Analysis Center: Royal Observatory of Belgium division on solar weather data
• solar irradiance (insolation): solar energy received per unit area in given time
• solar lithium problem: see lithium
  • surface abundance: quantity such as mass per surface area
• solar luminosities: see watt
• solar luminosity: luminosity unit representing the luminosity of the Sun
  • energy: physical state needed to do something
  • Sun: star at center of solar system
  • watt: SI unit of power
• solar mass: mass unit representing the mass of the Sun
• solar mass: see mass
  • Sun: star at center of solar system
• solar mass parameter: see standard gravitational parameter
  • solar mass: mass unit representing the mass of the Sun
• solar maximum: see sunspot
  • coronal loop: visible loop extending out of the Sun's surface and back
• Solar Maximum Mission: 1980s satellite to study the Sun during solar maximum
• Solar Mesophere Explorer: 1980s Earth atmospheric ozone research satellite
• solar minimum: see sunspot
  • magnetic field: magnetic force as distributed over a space
• solar model
• stellar structure: the presumed internal structure of stars
• solar motion: see solar apex
• solar nebula: cloud of gas and dust that formed the solar system
• solar nebular disk model
• nebular hypothesis: model positing solar system planets result from a solar disk
• solar neighborhood: Milky Way in the vicinity of the Sun
  • magnetic field: magnetic force as distributed over a space
• solar neutrino: neutrino from the Sun
  • Mikheyev-Smirnov-Wolfenstein effect: effect of matter on neutrino oscillation
  • solar neutrino unit: unit for the detection rate of neutrino detectors
• solar neutrino problem: see Mikheyev-Smirnov-Wolfenstein effect
• solar neutrino problem: see solar neutrino
  • Kamioka Observatory: Japanese underground particle detector
  • Sudbury Neutrino Observatory: Canadian underground neutrino detector
• solar neutrino unit: unit for the detection rate of neutrino detectors
  • solar neutrino: neutrino from the Sun
• solar neutrinos
• Sudbury Neutrino Observatory: Canadian underground neutrino detector
• solar noon (local noon): time at a locality when the Sun is at its highest
• solar noon: see solar time
  • equinox: point-in-time when tilt of Earth is neither toward nor away from the Sun
• Solar Orbiter: space probe investigating the Sun's surface and the heliosphere
• solar particle: particles from the Sun such as the solar wind
  • solar particle event: episode of higher velocity solar wind
• solar particle event: episode of higher velocity solar wind
  • solar storm: general term for events on the Sun
  • Sun surface features: features on the Sun's surface
• solar physics: study of the physics of the Sun
• solar powered satellite: concept for a satellite to collect and transfer energy to Earth
• Solar Probe (Parker Solar Probe): space probe investigating solar corona
• Solar Probe Plus (Parker Solar Probe): space probe investigating solar corona
• Solar Probe+ (Parker Solar Probe): space probe investigating solar corona
• solar prominence: see solar eruption
  • Sun surface features: features on the Sun's surface
• solar proton event (solar particle event): episode of higher velocity solar wind
  • solar storm: general term for events on the Sun
• solar radius: see Sun
• solar seismology: see asteroseismology
• solar storm: general term for events on the Sun
  • space weather: varying conditions in space affecting Earth and humans
• Solar Storm of 1859 (Carrington event): solar storm September 1-3 1859
• solar switchback (magnetic switchback): Z-shaped magnetic field lines
• solar system: the Sun and what's gravitationally bound to it
  • anomalous cosmic rays: cosmic rays with unexpectedly low energies
  • asteroid: minor planet without comet characteristics
  • asteroid belt: ring of orbiting planetoids/asteroids
  • asteroid family: set of asteroids based on similar orbits
  • binary minor planet: minor planet with another body orbiting it
  • CAI: calcium/aluminum specs in chondrites
  • Catalogue of Discoveries and Identifications of Minor Planets: 1982 catalog from Minor Planet Center
  • centaur: asteroid-like body orbiting among the outer planets
  • chondrite: stony class of meteorites not modified by melting
  • comet: Sun-orbiting object with coma and possible tail
  • damocloid: minor planet with a comet-like orbit
  • Deep Ecliptic Survey: late 1990s/early 2000s survey for KBOs
  • dwarf planet: round like a planet, only smaller
  • Earth: third solar system planet from the Sun
  • ephemeris: information on the position of a celestial body in the sky over time
  • equilibrium condensation model: chemical model explaining solar system planet abundances
  • grand tack hypothesis: solar system formation model with Jupiter and Saturn migrating
  • heliopause: boundary between solar wind and the interstellar medium
  • heliosheath: outer layer of the heliosphere beyond its termination shock
  • Hills Cloud: cloud of comets and minor planets around the solar system
  • interplanetary medium: matter in the solar system around and between planets
  • irregular moon: moon with an atypical orbit, such as retrograde
  • Jupiter: largest planet in the solar system
  • Kuiper Belt: further part of solar system beyond Neptune
  • late heavy bombardment: time after solar system planet-formation when many impacts occurred
  • long-period comet: comet with an orbital period of more than 200 years
  • Mars: well-explored planet in the solar system
  • Mars crosser: asteroid with an orbit that crosses that of Mars
  • Mercury: inner-most and smallest planet in the solar system
  • meteorite: rock found on Earth that is the remnant of a meteor
  • meteoroid: rocky object in solar system, smaller than an asteroid
  • minor planet: lesser solar system body without comet characteristics
  • near-Earth object: object orbiting the Sun that passes close to Earth
  • nebular hypothesis: model positing solar system planets result from a solar disk
  • Neptune: outer-most solar system planet
  • Nice model: model of the evolution of the solar system
  • oligarch: term for large planetesimals that dominate
  • Oort Cloud: cloud of distant comets surrounding the solar system
  • Oort Cloud Object: object in Oort Cloud such as a comet
  • orrery: mechanical device to simulate the solar system
  • Outer Solar System Origins Survey: 2013-2017 survey that searched for trans-Neptune objects
  • planet: round object orbiting a star that clears out its own orbital path
  • Planet Nine: theoretical planet beyond Neptune
  • planetoid: an asteroid or physically similar body
  • plutoid: Pluto-like dwarf planet
  • provisional designation: way to designate newly discovered solar system objects
  • Saturn: second largest planet in the solar system
  • solar constant: flux from the Sun at 1 AU
  • solar day: length of a solar system planet or Moon's day
  • solar nebula: cloud of gas and dust that formed the solar system
  • solar neighborhood: Milky Way in the vicinity of the Sun
  • solar system object: the Sun, solar system planets, minor planets, comets, and moons
  • solar wind: charged particles emanating from the Sun
  • SPACEWATCH: survey to study minor planets
  • SSSB: solar system body smaller than a dwarf planet
  • star system: a gravitationally bound set of a few stars
  • Sun: star at center of solar system
  • trans-Neptune object: minor planet beyond Neptune
  • Uranus: second outer-most solar system planet
  • Venus: second inner-most planet in the solar system
  • Voyager: space probes to observe planets and the edge of the solar system
  • vulcanoid: theoretical asteroid orbiting within Mercury's orbit
• solar system body (solar system object): the Sun, solar system planets, minor planets, comets, and moons
• solar system ephemerides: see ephemeris
• solar system object: the Sun, solar system planets, minor planets, comets, and moons
• solar telescope: telescope designed to observe the Sun
• Solar Terrestrial Relations Observatory (STEREO): two-satellite system to observe the Sun
• solar time: time based upon the position of the Sun in the Earth's sky
• solar transition region (transition region): middle layer of the Sun's atmosphere
• solar variation: see sunspot
• solar weather: see space weather
  • solar storm: general term for events on the Sun
  • Sun surface features: features on the Sun's surface
• solar wind: charged particles emanating from the Sun
  • Advanced Composition Explorer: satellite collecting solar wind and cosmic rays
  • aurora: light produced by atmosphere and solar wind
  • DISCOVR: space weather satellite
  • Genesis: NASA spacecraft that returned solar wind particles
  • heliopause: boundary between solar wind and the interstellar medium
  • heliosheath: outer layer of the heliosphere beyond its termination shock
  • Parker wind: model of the solar wind
  • solar particle event: episode of higher velocity solar wind
  • space weather: varying conditions in space affecting Earth and humans
  • stellar wind: gas or plasma emanating from a star
  • Voyager: space probes to observe planets and the edge of the solar system
• SOLAR-A
• Japan Aerospace Exploration Agency: Japan agency includes astronomical research
• Solar-flux monitor
• Dominion Radio Astrophysical Observatory: radio observatory in British Columbia, Canada
• solar-like oscillations: see asteroseismology
• solar-wind particles: see solar wind
• SoLEXS: see Aditya-L1
• solid angle: three-dimensional analog of an angle
  • field of view: angular measure of how much an optical instrument can view
• solid state detector: see particle spectrometer
• SolO (Solar Orbiter): space probe investigating the Sun's surface and the heliosphere
• SoloHI: see Solar Orbiter
• SOLSTICE: see Upper Atmosphere Research Satellite
• solstice: moment when Sun reaches its northern- or southern-most position
• Soltan argument: distant quasars imply SMBHs still exist
• Sombrero Galaxy: striking spiral galaxy with very large bulge
• Son of X-Shooter
• PESSTO: NTT survey following up on transients
• Sondage Infrarouge de Mouvement Propre (SIMP): 2000s infrared proper-motion survey
• SONEAR (Southern Observatory for Near Earth Asteroids Research): private telescope tracking NEOs
• sonic Mach number: see Mach number
• SOSP: see EURECA
• SOSS: see James Webb Space Telescope
• sound: see sounder
  • sound speed: speed at which compression waves traverse a gas
• sound horizon: see baryon acoustic oscillations
• sound speed: speed at which compression waves traverse a gas
• sounder: device to measure something at another depth
• sounding: see sounder
• sounding rocket: sub-orbital rocket to carry out measurements
  • AFGL Four Color Infrared Sky Survey: 1970s infrared survey
  • sounder: device to measure something at another depth
• source: astronomical object producing some observed signal
• source (radio source): astronomical object producing observable radio
• source confusion: see confusion limit
• source counts (radio source counts): using radio source population characteristics to determine curvature
• source function: measure indicating the effect of a material on EMR passing through
• South Africa
• HERA: low frequency radio telescope
• HIRAX: radio telescope array for 21-cm surveying
• Infrared Survey Facility: 140 cm reflector telescope that images in infrared
• MeerKAT: new radio telescope in South Africa
• MeerKAT Pulsar Timing Array: group of pulsars timed by MeerKAT
• MeerLICHT: South African telescope coordinated with MeerKAT
• South African Astronomical Observatory: South African observatory with SALT telescope
• Southern African Large Telescope: 10-meter telescope in South Africa
• Square Kilometre Array: planned radio telescope with square-kilometer collecting area
• South African Astronomical Observatory: South African observatory with SALT telescope
  • Infrared Survey Facility: 140 cm reflector telescope that images in infrared
  • MeerLICHT: South African telescope coordinated with MeerKAT
  • Southern African Large Telescope: 10-meter telescope in South Africa
• South African Pulsar Timing Array: see MeerKAT Pulsar Timing Array
• South Atlantic Anomaly: see Van Allen belts
• south galactic pole: see galactic north
• South Korea
• COSINE-100: dark matter detection experiment in South Korea
• south node: see orbital element
• South Pole
• ACBAR: instrument used in a CMB survey
• BICEP2: survey to measure the polarization of the CMB
• CMB Stage-4: planned 2020s-generation of ground CMB observations
• DASI: 2000-2003 South Pole CMB telescope
• IceCube: neutrino detector at the South Pole
• QUaD: survey to measure the polarization of the CMB
• South Pole Station: science station at the South Pole
• South Pole Telescope: a millimeter/microwave telescope at South Pole
• South Pole Station: science station at the South Pole
  • BICEP2: survey to measure the polarization of the CMB
  • QUaD: survey to measure the polarization of the CMB
• South Pole Telescope: a millimeter/microwave telescope at South Pole
• Southeast Asia Astronomy Network: astronomy research/education organization
• Southern African Large Telescope: 10-meter telescope in South Africa
• Southern Astrophysical Research Telescope (SOAR Telescope): 4.1 m reflector telescope in Chile
  • Cerro Tololo Inter-American Observatory: NOIRLab observatory in Chile with Blanco telescope
• Southern Great Wall (Sculptor Wall): large slab of galaxies
• southern lights: see aurora
• Southern Observatory for Near Earth Asteroids Research: private telescope tracking NEOs
• Southern Ring Nebula (NGC 3132): PN of interest in southern sky
• Southern Sky Atlas: see UK Schmidt Survey
• Southern Sky Redshift Survey: 1980s/1990s redshift survey of southern galaxies
  • UZC-SSRS2 Group Catalog: 2002 catalog of galaxy groups
• Southern Sky Survey (SkyMapper Southern Survey): digital survey of the southern hemisphere sky
• Southern Stellar Stream Spectroscopic Survey: spectroscopic survey of seven southern-hemisphere stellar streams
• Southern Supercluster
• Laniakea Supercluster: group of clusters including the Local Group
• Southern Wall (Sculptor Wall): large slab of galaxies
• southern zone of avoidance: see zone of avoidance
• Southwest Research Institute: Texas research organization
• SOVA: see EURECA
• SoXS: see New Technology Telescope
  • PESSTO: NTT survey following up on transients
• SP: see SELENE
• SP: see rare designator prefixes
• SP77: see rare designator prefixes
• space
• A Broadband Imaging X-ray All-sky Survey: failed 1999 space mission
• AFGL Four Color Infrared Sky Survey: 1970s infrared survey
• AMPTE: three spacecraft experimenting on Earth magnetosphere
• AMS-02: particle detector on ISS
• Astronomical Netherlands Satellite: 1970s X-ray/ultraviolet space telescope
• Berkeley Extreme and Far-UV Spectrometer: 1990s UV spectrometer used on two Space Shuttle missions
• British Interplanetary Society: space-exploration/research advocacy organization
• Broad Band X-Ray Telescope: 1990s Astro-1 Space Shuttle X-ray telescope
• Combined Release and Radiation Effects Satellite: 1990s satellite investigating Earth's magnetosphere
• Comet Nucleus Sample Return: concept study for comet mission
• Comet Rendezvous Asteroid Flyby: 1980s/1990s NASA comet exploration plan
• Coupled Ion-Neutral Dynamics Investigation: space weather investigation instruments on USAF spacecraft
• CubeSat: type of small satellite built around a set of modular parts
• decadal survey: periodic NASA effort to plan for future astrophysical research
• DECIGO: proposed Japanese space mission to detect gravitational waves
• eROSITA: Russian/German space X-ray telescope launched in 2019
• European Space Research Organisation: 1960s-1970s European collaboration
• ExoMars: program to search for signs of life on Mars
• FAUST: 1990s ultraviolet space telescope used on two Space Shuttle missions
• flyby: space probe flying close to a planet or moon
• Gabbard plot: plot showing apogee-perigee range of select orbiting debris
• Glazar: 1980s UV space telescope on MIR space station
• Global-scale Observations of the Limb and Disk: satellite instrument to study ionosphere regarding space weather
• GNOSIS: initiative to explore the problem of space debris
• gravity assist: method of boosting the speed of a spacecraft
• Ground-Base Electro-Optical Deep Space Surveillance: initiative to track artificial spacecraft including space junk
• halo orbit: type of orbit around an unstable Lagrangian point
• Hopkins Ultraviolet Telescope: 1990s ultraviolet space telescope used on two Shuttle Shuttle missions
• Indian Space Research Organisation: national science and technology agency
• Interstellar Medium Absorption Profile Spectrograph: 1980s/1990s UV spectrometer
• ion engine: type of electrical spacecraft engine
• IRTS: 15-cm infrared telescope on Japanese satellite
• K2: second Kepler mission that worked around failed equipment
• Kessler syndrome: low-Earth-orbit debris growing out of control
• Kvant 1: scientific module on Mir space station
• launch window: time period for launching space probes traveling a particular route
• LISA: proposed space mission to detect gravitational waves
• Magnetospheric Multiscale Mission: four spacecraft making Earth magnetosphere measurements
• Mars Exploration Rover: mission to Mars with two rovers
• Mars Pathfinder: 1990s mission to Mars with rover
• Mars Science Laboratory: mission to Mars with rover
• Medium-class Explorer Program: NASA program for small science spacecraft
• microsatellite: NASA term for a 10-100 kg small satellite
• Mission Shakti: Indian antisatellite test.
• MMRTG: power source for space probes
• Mu Space Engineering Spacecraft: series of Japanese astronomy space missions
• nanosatellite: NASA term for a 1-10 kg small satellite
• NASA Standard Breakup Model: model maintained by NASA of how satellites fragment
• New Gravitational Wave Observatory: past proposal for space mission to detect gravitational waves
• NICER: space X-ray mission specifically to view neutron stars
• NIRCam: near infrared imager on JWST
• NIRSpec: near infrared spectrograph on JWST
• orbital decay: gradual reduction in radius of an orbit
• Orbiting Astronomical Observatory: series of 1960s-1970s NASA space telescopes
• Orbiting Wide-angle Light Collectors: space mission concept to detect cosmic rays through Earth atmosphere light flashes
• Orion space telescopes: two Russian 1970s UV space telescopes
• PAMELA: cosmic ray detector attached to satellite
• planetary protection: the principle of avoiding the contamination of planets with Earth life forms
• POEMMA: planned space cosmic-ray neutrino observatory
• primary mission: the minimum operation expected of a scientific space mission
• PUNCH: 4 microsatellites to observe the Sun
• Radioisotope Thermoelectric Generator: type of spacecraft power source for instruments
• RELIKT-1: instrument on 1980s Soviet satellite to view the CMB
• satellite constellation: group of many coordinated satellites such as for communication
• satellite constellation: type of communication system incorporating tens/hundreds of satellites
• Small Explorer Program: NASA program for small science spacecraft
• small satellite: NASA term for a satellite of 1200 kg or less
• Space Launch System: launch rocket in development, e.g., for future astronomical projects
• Space Studies Institute: organization promoting interest in and use of space technology
• Space Transport System: early NASA plan for a Space-Shuttle-like vehicle
• Spacelab: reusable laboratory that was an optional Space Shuttle payload
• SPARTAN: series of astronomy satellites launched/retrieved by Space Shuttles
• Starshot: plan for mission to fly by Alpha Centauri
• stationkeeping: spacecraft operation to keep it in its orbit
• Terrestrial Planet Finder: plan for space telescopes to find smaller exoplanets
• THEMIS: set of satellites studying the Earth's magnetic field
• TianQin: proposed Chinese space mission to detect gravitational waves
• Tracking and Data Relay Satellite System: NASA satellites used for communication and tracking of space probes
• Tubingen Ultraviolet Echelle Spectrometer: 1990s UV spectrometer used on two Space Shuttle missions
• two-line element set: data format to record the position and motion of a satellite
• Ultraviolet Imaging Telescope: 1990s ultraviolet space telescope used on two Space Shuttle missions
• Ulysses: space mission to observe the Sun from off the ecliptic
• UVSC Pathfinder: instrument to observe the Sun
• Vela: 1960s military satellites to detect nuclear tests
• Venus-Earth-Earth Gravity Assist: interplanetary method of Galileo spacecraft
• Voyager: space probes to observe planets and the edge of the solar system
• Wisconsin Ultraviolet Photo-polarimeter Experiment: 1990s ultraviolet space telescope used on two Shuttle Shuttle missions
• space debris
• GNOSIS: initiative to explore the problem of space debris
• Space Flyer Unit: see IRTS
• Space Force (United States Space Force): US space-related military organization
• Space Infrared Telescope Facility (Spitzer Space Telescope): retired infrared space telescope
• Space Infrared Telescope for Cosmology and Astrophysics (SPICA): plan for a future space IR telescope
• Space Interferometry Mission: past space interferometer plan for parallax and exoplanet detection
• space junk: see Ground-Base Electro-Optical Deep Space Surveillance
  • GNOSIS: initiative to explore the problem of space debris
• Space Launch System: launch rocket in development, e.g., for future astronomical projects
  • Origins Space Telescope: concept for 2030s large space IR telescope
• Space Research Organization of the Netherlands: national research institution
• Space Shuttle
• Berkeley Extreme and Far-UV Spectrometer: 1990s UV spectrometer used on two Space Shuttle missions
• EURECA: 1990s ESA satellite with a number of experiments
• FAUST: 1990s ultraviolet space telescope used on two Space Shuttle missions
• Hopkins Ultraviolet Telescope: 1990s ultraviolet space telescope used on two Shuttle Shuttle missions
• Interstellar Medium Absorption Profile Spectrograph: 1980s/1990s UV spectrometer
• Magellan: 1980s/1990s Venus probe
• Space Launch System: launch rocket in development, e.g., for future astronomical projects
• SPARTAN: series of astronomy satellites launched/retrieved by Space Shuttles
• Tubingen Ultraviolet Echelle Spectrometer: 1990s UV spectrometer used on two Space Shuttle missions
• Ultraviolet Imaging Telescope: 1990s ultraviolet space telescope used on two Space Shuttle missions
• Wisconsin Ultraviolet Photo-polarimeter Experiment: 1990s ultraviolet space telescope used on two Shuttle Shuttle missions
• Space Studies Board: National Academy of Sciences unit re astronomy an research via spacecraft
• Space Studies Institute: organization promoting interest in and use of space technology
• Space Surveillance Network (United States Space Surveillance Network): US survey-effort of space objects of interest
• Space Surveillance Telescope: 3.5-m US telescope to discover and monitor objects in space
  • LINEAR: survey of near-Earth objects
• Space Telescope (Hubble Space Telescope): observatory-satellite with 2.4-meter reflective telescope
• Space Telescope Science Data Analysis System: software designed for analysis of HST data
• Space Telescope Science Institute: science operator of space telescopes
  • MAST: archive of data from surveys and missions
• Space Transport System: early NASA plan for a Space-Shuttle-like vehicle
• space weather: varying conditions in space affecting Earth and humans
  • ESA Vigil: plan for space-weather warning satellite at L5
  • solar storm: general term for events on the Sun
  • WSA-Enlil: computer model of heliosphere for space weather prediction
• Space Weather Modeling Framework (SWMF): software package of tools for modeling space weather
• space weathering: see weathering
• space-like: see spacetime diagram
  • geodesic: equivalent to a straight line within curved space
• spacecraft
• Aditya-L1: 2023 spacecraft viewing Sun and analyzing solar wind
• Advanced Composition Explorer: satellite collecting solar wind and cosmic rays
• Aeronomy of Ice in the Mesosphere: spacecraft to study upper Earth atmosphere
• AGILE: Italian space gamma-ray observatory
• AKARI: Japanese space infrared telescope
• ALEXIS: 1990s soft X-ray transient monitor
• Arcus: X-ray space telescope plan aiming for 2031 launch
• ARGOS: 1999 technology-research satellite
• ARIEL: planned space mission for exoplanet spectrography
• Ariel 5: 1970s X-ray space telescope
• ASCA: 1990s Japanese space X-ray telescope
• AstroSat: Indian observatory satellite
• ATHENA: planned ESA X-ray space telescope
• Autonomous Space Transport Robotic Operations: experiment re robotic satellite servicing/refueling in space
• AXIS: concept for space X-ray observatory
• BepiColombo: mission to Mercury
• BeppoSAX: Italian-Dutch space X-ray telescope
• Burst and All Sky Imaging Survey: late 1990s GRB-observer satellite proposal
• CAESAR: planned space mission to return a sample of a comet
• Cassini: explorer spacecraft sent to Saturn
• Chandra X-ray Observatory: space X-ray telescope
• CHEOPS: space telescope in development to measure radii of exoplanets
• CHIPS: small satellite to investigate ISM plasma
• Compton Gamma Ray Observatory: 1990s space observatory for gamma ray observation
• CONTOUR: failed 2002 NASA astroid flyby mission
• COROT: observatory-satellite to look for transiting exoplanets and stellar oscillations
• Cos-B: 1970s satellite for studying gamma rays
• Cosmic Background Explorer: 1989 satellite for surveying the CMB
• Cosmic Dawn Intensity Mapper: NASA concept for space telescope for intensity mapping
• CubIXSS: solar spectrometer satellite concept
• CUTE: CubeSat ultraviolet space telescope
• Darwin: past plan for space telescopes acting as an interferometer
• DAVINCI: planned NASA Venus orbiter
• Dawn: explorer spacecraft sent to asteroids Vesta and Ceres
• Deep Impact: mission to create and observe an impact with a comet
• Deep Space 1: 1998-2001 mission to fly by asteroid
• DISCOVR: space weather satellite
• Dragonfly: Titan flying rover under development
• Einstein Probe: Chinese X-ray space observatory
• Enceladus Life Finder: mission to search for life on Saturn moon Enceladus
• Enceladus Orbilander: concept for a NASA mission to Enceladus
• EnVision: planned 2030s ESA Venus orbiter
• EPOXI: mission using Deep Impact for further exploration
• ESA Vigil: plan for space-weather warning satellite at L5
• Euclid: survey observatory-satellite to measure dark energy
• EURECA: 1990s ESA satellite with a number of experiments
• Europa Clipper: NASA Europa space probe launched in 2024
• Europa Lander: plan for a late 2020s Europa probe landing on the surface
• Exo-S: a study on the concept of a starshade mission
• EXOSAT: 1980s European space X-ray telescope
• eXTP: plan for a space X-ray telescope
• Extreme Ultraviolet Explorer: 1990s ultraviolet space telescope
• Far Ultraviolet Spectroscopic Explorer: early 2000s space telescope for short-wavelength ultraviolet
• Fast On-orbit Rapit Recording of Transient Events: satellite viewing radio and optical transients on Earth
• Fermi: satellite for studying gamma rays
• FINESSE: planned space mission for exoplanet spectrography
• Full-sky Astrometric Mapping Explorer: early 2000s proposal for an astrometric space telescope
• Gaia: astrometry survey satellite launched in 2013
• GaiaNIR: concept for a Gaia follow-on including NIR astrometry
• Galaxy Evolution Explorer: observatory-satellite with 50-cm ultraviolet telescope
• Galileo: circa 1990s space mission to Jupiter
• Gamow Explorer: proposal for GRB space mission
• Genesis: NASA spacecraft that returned solar wind particles
• Ginga: 1980s Japanese space X-ray telescope
• Giotto: 1980s space mission carrying out a Comet Halley flyby
• GRAIL: 2011 NASA lunar orbiters to collect gravity data
• GRANAT: observatory-satellite for detecting gamma rays and X-rays
• Gravity Probe B: space experiment re GR effects of Earth gravity
• HabEx: proposed space mission to directly image exoplanets
• HALCA: Japanese space radio telescope operating 1997-2005
• Hayabusa2: JAXA mission that returned a sample of an asteroid
• HEAO-1: 1977 X-ray observatory space mission
• HEAO-2: 1978 X-ray observatory space mission
• Herschel Space Observatory: infrared observatory-satellite with 3.5-meter reflector
• High Definition Space Telescope: proposed 12 m space telescope
• High Energy Transient Explorer: 2000s space multi-band GRB observatory
• Hipparcos: ESA astrometry space observatory circa 1990
• Hisaki: retired Japanese space ultraviolet telescope
• Hitomi: 2016 Japanese space X-ray telescope
• Hope Probe: UAE Mars orbiter currently studying Mars
• Hubble Space Telescope: observatory-satellite with 2.4-meter reflective telescope
• HXMT: space X-ray observatory launched in 2017
• IMAGE­: satellite mission to study magnetosphere
• IMAP: future solar science probe
• Infrared Space Observatory: 1990s 60-cm infrared space telescope
• InSight: NASA Mars mission to study its interior
• INTEGRAL: European gamma ray observatory-satellite
• International Cometary Explorer: 1980s space mission flying by comets
• International Space Station: long-term manned space station operated by numerous nations
• International Ultraviolet Explorer: 1980s ultraviolet space telescope
• Interstellar Boundary Explorer: satellite observing the ISM/heliosphere boundary
• IRAS: 1983 satellite that surveyed the sky in infrared
• IXPE: space observatory with X-ray polarimeters
• James Webb Space Telescope: 6.5-meter infrared space telescope at L2
• Joint European Telescope for X-ray astronomy: 1990s X-ray space observatory never launched
• JUICE: mission to Jupiter in development
• Juno: mission to Jupiter
• Kepler Telescope: space telescope that watched stars for exoplanets
• LARES: satellite to test a general relativity effect
• LCROSS: space probe observing the lunar poles
• LiteBIRD: planned spacecraft to map CMB polarization
• Lucy: space probe to observe Jupiter Trojan asteroids
• Lunar Prospector: NASA 1998 lunar orbiter
• Lunar Reconnaissance Orbiter: space probe orbiting the Moon
• LUVOIR: plan for a space-based telescope
• Lynx: concept for space X-ray observatory
• Magellan: 1980s/1990s Venus probe
• Mars 2020: Mars rover mission currently on Mars after 2021 landing
• Mars Climate Orbiter: failed Mars 1990s probe
• Mars Express: Mars probe launched by ESA in 2003
• Mars Global Surveyor: Mars probe launched by NASA in 1996
• Mars Observer: failed 1992-1993 Mars orbiter mission
• Mars Odyssey: Mars orbiter launched by NASA in 2001
• Mars Polar Lander: failed 1999 Mars lander mission
• Mars Reconnaissance Orbiter: Mars probe launched by NASA in 2005
• MAVEN: Mars orbiter to study its atmosphere
• MAXI: Japanese X-ray camera on the International Space Station
• Measuring Oscillations in Nearby Stars: past plan for asteroseismology mission
• MESSENGER: Mercury probe launched by NASA in 2004
• Midcourse Space Experiment: 1990s space telescope
• MMX: Japanese probe to bring back a sample of a Martian moon
• MOST: 2000s observatory-satellite looking for stellar oscillations
• Near Earth Asteroid Prospector: planned space mission to look at NEOs as mining sources
• NEAR Shoemaker: space mission to an asteroid
• NEO Surveyor: planned space observatory to detect and monitor NEOs
• NEOSSat: small spacecraft tracking NEOs
• New Horizons: explorer spaceship sent to Pluto
• New Worlds Mission: plan for space occulter to facilitate the view of exoplanets
• NuSTAR: space telescope for high-energy X-rays
• Origins Space Telescope: concept for 2030s large space IR telescope
• OSAM-1: prototype space robot for servicing satellites
• OSIRIS-REx: space mission aiming to return a sample of an asteroid
• OSO 7: 1970s observatory-satellite for viewing the Sun
• OSO 8: 1970s observatory-satellite for viewing the Sun
• Parker Solar Probe: space probe investigating solar corona
• Phoenix: Mars polar-region probe launched by NASA in 2007 with lander
• Pioneer Venus Orbiter: NASA Venus probe launched 1978
• PIXIE: satellite-concept to to survey CMB polarization
• Planck: microwave telescope in space
• PLATO: planned observatory-satellite aimed at finding exoplanets
• PRIMA: concept for 2030s NASA 1.8-m FIR space telescope
• Psyche: space mission on its way to asteroid Psyche
• Roman Space Telescope: proposed near-infrared space observatory
• Rosalind Franklin: Mars rover in development for 2028 launch
• ROSAT: 1990s German space X-ray telescope
• Rosetta: space probe that visited a comet
• RXTE: space mission to time X-ray variations
• Satech-01: Chinese experimental spacecraft
• SELENE: 2007-2008 Japanese lunar probe
• Small Astronomy Satellite 2: 1970s NASA gamma ray space telescope
• Small Astronomy Satellite 3: 1970s NASA X-ray space telescope
• SMART-1: Swedish lunar orbiter operational 2003-2006
• Solar and Heliospheric Observatory: satellite observing the Sun
• Solar Dynamics Observatory: 2010 satellite observing the Sun
• Solar Maximum Mission: 1980s satellite to study the Sun during solar maximum
• Solar Mesophere Explorer: 1980s Earth atmospheric ozone research satellite
• Solar Orbiter: space probe investigating the Sun's surface and the heliosphere
• solar powered satellite: concept for a satellite to collect and transfer energy to Earth
• Space Interferometry Mission: past space interferometer plan for parallax and exoplanet detection
• Spektr-R: 10 m space radio telescope
• Spektr-RG: Russian-German X-ray observatory launched in 2019
• SPHEREx: all-sky spectral survey space-mission plan
• SPICA: plan for a future space IR telescope
• Spitzer Space Telescope: retired infrared space telescope
• STAR-X: plan for a future X-ray space telescope
• Stardust: space mission that collected and returned comet coma dust
• STEREO: two-satellite system to observe the Sun
• STROBE-X: space X-ray telescope plan
• Submillimeter Wave Astronomy Satellite: submillimeter space telescope operating 1998-2004
• Suzaku: space X-ray telescope
• SWFO-L1: future NOAA space-weather warning satellite
• Swift: satellite for studying gamma-ray bursts
• TD-1A: 1970s European observatory-satellite with UV telescopes
• THESEUS: plan for X-ray/Gamma-ray transient space mission
• Thousand Astronomical Units: 1980s plan for space probe to travel 1000 AU over 50 years
• Tiangong space station: Chinese manned space laboratory under construction in space
• Tianwen-1: active Chinese Mars rover/orbiter mission
• TIMED: space probe observing Earth upper atmosphere for solar effects
• TRACE: former solar observing satellite
• Trace Gas Orbiter: ESA and Russian Mars orbiter-probe launched in 2016
• Transiting Exoplanet Survey Satellite: observatory-satellite searching for transiting exoplanets
• Uhuru: 1970 X-ray space telescope
• ULTRASAT: future satellite to detect UV transients
• Upper Atmosphere Research Satellite: 1990s spacecraft to observe Earth ozone layer
• Uranus Orbiter and Probe: concept for mission to Uranus
• Venus Express: Venus probe launched by ESA in 2005
• Venus Orbiting Imaging Radar: 1980s plan for Venus probe to map the surface
• VERITAS: planned NASA Venus orbiter
• Wide Field Infrared Explorer: partly-failed 1999 infrared satellite
• Wide-field Infrared Survey Explorer: infrared space telescope aimed at an all-sky survey
• Wilkinson Microwave Anisotropy Probe: spacecraft that measured variations in the cosmic background radiation
• Wind: spacecraft measuring solar wind
• XMM-Newton: X-ray observatory-satellite operated by ESA
• XRISM: X-ray space telescope launched in 2023
• XTP: past plan for a space X-ray telescope
• Yohkoh: 1990s Japanese solar observatory spacecraft
• Spaceguard Centre: UK private observatory dedicated to NEOs
• SpaceGuard Foundation: private organization to discover and track NEOs
• Spacelab: reusable laboratory that was an optional Space Shuttle payload
  • FAUST: 1990s ultraviolet space telescope used on two Space Shuttle missions
  • Hopkins Ultraviolet Telescope: 1990s ultraviolet space telescope used on two Shuttle Shuttle missions
  • Ultraviolet Imaging Telescope: 1990s ultraviolet space telescope used on two Space Shuttle missions
  • Wisconsin Ultraviolet Photo-polarimeter Experiment: 1990s ultraviolet space telescope used on two Shuttle Shuttle missions
• spacetime: four dimensions: time and the three space dimensions
  • curvature: unflatness of space
  • geodesic: equivalent to a straight line within curved space
  • worldline: path of an object through space and time
• spacetime diagram: graph of simplified spacetime, with fewer space dimensions
• spacetime interval: see relativistic invariance
• spacetime interval: see spacetime
• SPACEWATCH: survey to study minor planets
• Spacewatch 1.8-m telescope: see SPACEWATCH
• SpaceX
• Space Launch System: launch rocket in development, e.g., for future astronomical projects
• SPAD (Geiger-avalanche photodiode): type of solid state photon sensor
• SPADUS: see ARGOS
• spaghettification: see tidal force
  • tidal disruption event: star pulled apart by black hole tidal forces
• Spain
• ANAIS-112: dark matter detection experiment in Spain
• Calar Alto Observatory: observatory on mountain in mainland Spain
• CALIFA: spectroscopic map of 600 galaxies
• GISMO: 2 mm bolometer camera on IRAM 30 m telescope
• Instituto de Astrofísica de Canarias: research institute on Canary Islands
• IRAM 30m Telescope: millimeter-range radio telescope in Sierra Nevada, Spain
• Laboratorio de Astrofisica Espacial y Fisica Fundamental: Spanish astrophysics laboratory
• Ministerio de Ciencia e Innovaciónes: Spanish science ministry
• Red de Infraestructuras de Astronomie: Spanish astronomy research organization
• SPAN: see Parker Solar Probe
• Spanish
• Centro Astronómico Hispano-Alemán: German-Spanish Astronomical Center at Calar Alto.
• spar: see solar telescope
• SPARC: see MITgcm
• SPARC/MITgcm: see MITgcm
• SpARCS: see Spitzer Space Telescope
• spark chamber: type of ion detector
• SPARSEPAK: see WIYN 3.5m Telescope
• SPARTAN: series of astronomy satellites launched/retrieved by Space Shuttles
• SPARTAN: see SOAR Telescope
• SPARTAN-201: see SPARTAN
• sparticle: see supersymmetry
• spatial correlation function (N-point function): general term for analyses-techniques of spatial data
• spatial direction: see imaging spectrometer
• spatial Fourier transform
• 2D Fourier transform: type of transformation of 2D functions used for analysis and manipulation
• spatial frequency (wavenumber): reciprocal of wavelength
  • detective quantum efficiency: measure of instrument's ability to create images
  • frequency: number of cycles per unit of time, such as waves per second
• spatial heterodyne spectrometer: see heterodyne spectrometer
• spatial pixel: see spaxel
  • data cube: three-dimensional array of numerical data
• spatial resolution (angular resolution): measure of a telescope's ability to distinguish spatial detail
• spaxel: like an image-pixel but with a SED for the location
  • data cube: three-dimensional array of numerical data
• SPB (slowly-pulsating B-star): B-star with pulsation periods of more than half a day
• SPB: see SuperBIT
• SPC: see Parker Solar Probe
• SPD (spectral power distribution): function of power versus wavelength or frequency
• SPE (solar particle event): episode of higher velocity solar wind
  • solar storm: general term for events on the Sun
  • Sun surface features: features on the Sun's surface
• SpEC: code to solve general relativity problems
• Special Breakthrough Prize: Breakthrough Prize award in addition to the year's annual awards
• special relativity: physics explaining how the speed of light can be constant
• special relativity: see relativity
  • blue shift: shortening of wavelengths due to Doppler effects
  • cosmological redshift: redshift of distant objects due to the Hubble expansion
  • Lorentz transformation: equations describing the effect of relative motion on length and velocity
  • mass: object's quality that determines the effects of forces and gravity
  • quantum field theory: reworking of quantum mechanics incorporating fields
  • redshift: change to longer wavelengths due to Doppler effects
  • spacetime: four dimensions: time and the three space dimensions
  • worldline: path of an object through space and time
• specific angular momentum: absolute angular momentum divided by mass
• specific heat: ratio of added temperature to added heat for a material
• specific heat capacity (specific heat): ratio of added temperature to added heat for a material
• specific humidity: see humidity
• specific intensity: intensity per unit wavelength or frequency
  • brightness temperature: temperature of an equivalent black body in terms of spectral radiance
  • flux density: measure of the strength of a radio signal
  • intensity: power reaching a surface from a specific source
  • Planck function: yields black-body spectrum curve
  • radiance: measure of EMR to/from a solid angle through an area
• specific mean intensity: see specific intensity
  • intensity: power reaching a surface from a specific source
• specific star formation rate: see star formation rate
• specific volume: ratio of volume to mass
• specification
• angular resolution: measure of a telescope's ability to distinguish spatial detail
• cadence: period between observations
• elevation range: measure of how high and low a telescope can be pointed
• emissivity: measure of a material's efficiency at radiating thermal radiation
• exit pupil: size of the image as presented to the eye
• field of view: angular measure of how much an optical instrument can view
• Fsky: fraction of the sky, e.g., what a survey covers
• noise-equivalent power: signal power that equals the noise
• pointing error: discrepancy in telescope's aim
• scan speed: the speed at which the telescope changes angle on the sky while observing
• sensitivity function: function of wavelength giving the sensitivity of an instrument
• spectral resolution: measure of a spectrograph's ability to resolve features of the spectrum
• Strehl ratio: measure of optical aberration
• wavefront error: measure of a class of telescope distortion
• specificity: see balanced accuracy
• Speckle: see Large Altazimuth Telescope
• speckle imager: see speckle imaging
• speckle imaging: method of combining short-term images to yield better resolution
• speckle interferometry (speckle masking): speckle suppression technique using a calculation of the bispectrum
• speckle masking: speckle suppression technique using a calculation of the bispectrum
• speckle noise: see speckle suppression
• speckle suppression: methods of reducing noise in telescope observations
  • shift-and-add: common speckle-suppression technique
  • speckles: image flaws such as extraneous spots
• speckles: image flaws such as extraneous spots
• spectral band: set of related, closely-packed spectral lines
• spectral brightness (specific intensity): intensity per unit wavelength or frequency
  • flux density: measure of the strength of a radio signal
  • radiance: measure of EMR to/from a solid angle through an area
• spectral class: overall classification of stars based upon spectral features
  • A-type star: star with spectral characteristics of around 8500 K
  • B-type star: star with spectral characteristics of around 10000-30000 K
  • carbon star: star with more carbon than oxygen in its atmosphere
  • F-type star: spectral class of star a bit hotter than then Sun
  • G-type star: stars spectrally similar to the Sun
  • K-type star: spectral class of star a bit cooler than the Sun
  • L-type star: spectral type of star cooler than an M-type star
  • M-type star: spectral class of star with a temperature in the vicinity of 2500 K
  • O-type star: star with spectral characteristics of above 30000 K
  • S-type star: type of star with lines indicating zirconium
  • spectral type: classification of stars based upon spectral features
  • T-type star: brown dwarf with a temperature in the vicinity of 1000 K
  • Y-type star: brown dwarf with a temperature less than 700 K
• spectral classification (spectral class): overall classification of stars based upon spectral features
• spectral continuum (continuum): portion of a continuous spectrum not affected by a spectral feature
• spectral correlator: correlator that also functions as a spectrograph
• spectral density: strength of power or energy as a function of frequency
• spectral differential imaging: see speckle suppression
• spectral direction: see imaging spectrometer
• spectral disentangling: see blended spectra
• Spectral Einstein Code (SpEC): code to solve general relativity problems
• spectral emissivity: see emissivity
• spectral energy distribution: function or plot of brightness at each wavelength in the spectrum
  • spectral power distribution: function of power versus wavelength or frequency
• spectral energy distribution fitting: see spectral energy distribution
• Spectral Energy Distribution Machine: see Palomar 60-inch Telescope
• spectral feature: recognizable feature of a spectrum
  • 2175 angstrom feature: prominent absorption feature in ISM
  • absorption line: dark line within a spectrum
  • Balmer jump: abrupt change in stellar spectrum at the Balmer series wavelength limit
  • Compton reflection: recognizable emission due to a gas or plasma's Compton scattering
  • continuous absorption: the absorption of a whole section of a spectrum
  • emission line: narrow frequency-region of a spectrum with higher intensity
  • Gunn-Peterson trough: spectral feature in EMR from redshift 6+
  • line blanketing: so many bunched spectral lines that they cannot be distinguished
  • Lyman break: abrupt change in galaxy spectrum at the Lyman series wavelength limit
  • Lyman continuum: absorption continuum beginning at Lyman limit
  • P Cygni profile: emission-line shape including a blue-shifted absorption feature
  • spectral line: dark or bright line in a spectrum
  • spectral signature: spectral characteristics indicating the emitting material and conditions
  • vegetation red edge: wavelength cut-off point in the reflectivity of typical plants
• spectral feature extraction: see spectral feature
• spectral flux: see radiant flux
• spectral flux density: flux or power of radiation per unit area per unit wavelength
• spectral flux density (flux density): measure of the strength of a radio signal
• spectral index: power by which an object's flux depends on frequency
• spectral intensity (specific intensity): intensity per unit wavelength or frequency
  • flux density: measure of the strength of a radio signal
• spectral irradiance (flux density): measure of the strength of a radio signal
  • irradiance: EMR power reaching a surface
• spectral line: dark or bright line in a spectrum
  • continuum: portion of a continuous spectrum not affected by a spectral feature
  • Schuster-Schwarzschild model: simplified model of a star's production of absorption lines
  • spectral line designation: labels used to identify spectral lines
• spectral line broadening (line broadening): processes causing a spectral line to have width
• spectral line designation: labels used to identify spectral lines
• spectral line designator: see spectral line designation
• spectral line energy distribution: function or plot of brightness of lines in a spectrum
  • carbon monoxide: compound of carbon and oxygen, one atom each
• spectral line index
• Lick indices: defined set of spectral line indexes for stars
• spectral line profile: see Voigt profile
• spectral line shape: yields information about source
• spectral line shape: see line shape function
• spectral line tomography (line tomography): using double-peaked spectral lines to place constituents of a disk
• spectral method: method of numerically solving differential equations
• spectral photometry: see photometry
• spectral photon distribution: see spectral power distribution
• spectral pixel: see spaxel
  • data cube: three-dimensional array of numerical data
• spectral power distribution: function of power versus wavelength or frequency
• spectral radial velocity: see radial velocity
• spectral radiance (specific intensity): intensity per unit wavelength or frequency
• spectral radiance: see intensity
• spectral radiance: see radiance
  • Planck function: yields black-body spectrum curve
  • radiative transfer: energy transfer in the form of electromagnetic radiation
• spectral resolution: measure of a spectrograph's ability to resolve features of the spectrum
• spectral retrieval: see retrieval
• spectral signature: spectral characteristics indicating the emitting material and conditions
  • spectral feature: recognizable feature of a spectrum
• spectral temperature: temperature-measure of a source based on a spectrum
• spectral type: classification of stars based upon spectral features
  • spectral class: overall classification of stars based upon spectral features
• spectral-line mapping
• spectral line: dark or bright line in a spectrum
• SPECTRE: an interactive spectrum analysis software package
• SPECTRE: see IRTF
• Spectro-photometer for the History of the Universe, Epoch of Reionization, and Ices Explorer (SPHEREx): all-sky spectral survey space-mission plan
• Spectro-polarimetric High-contrast Exoplanet Research (SPHERE): VLT instrument for imaging exoplanets
• spectro-z: see photometric redshift
• spectrograph: device to record the spectrum of incoming light
  • CfA digital speedometer: 1980s/90s spectrograph aimed at radial velocity measurements
  • CorMASS: near-infrared spectrograph
  • COSIE: EUV spectrograph to analyze the corona
  • CRIRES: high resolution IR echelle spectrometer
  • Dark Energy Spectroscopic Instrument: new instrument for measuring red-shift of distant objects
  • ESIS: EUV spectrograph for solar corona observation
  • G-CLEF: spectrograph on the GMT
  • HARMONI: spectrograph planned for E-ELT
  • HARPS: high-precision spectrograph for exoplanet searches
  • HARPS-N: high-precision spectrograph for exoplanet searches in Canary Islands
  • HERMES: four-channel spectrograph on the Anglo-Australian Telescope
  • Interstellar Medium Absorption Profile Spectrograph: 1980s/1990s UV spectrometer
  • Keck Planet Finder: Keck I spectrograph for RV measurements
  • KMOS: 2-micron spectrograph on ESO VLT
  • Mimir: multi-function near-infrared instrument on Perkins Telescope
  • Multi-object Optical and Near-IR Spectrograph: advanced spectrograph under development for VLT
  • NEWS: planned near-infrared spectrometer on Discovery Channel Telescope
  • NIRPS: near-infrared extension to HARPS spectrograph
  • NIRSpec: near infrared spectrograph on JWST
  • spectrography: charting the strengths of different electromagnetic wavelengths
  • spectrometer: device to measure light by wavelength across its spectrum
  • spectroscope: device to study the spectrum of incoming light
  • spectroscopy: measurement of light with various electromagnetic wavelengths
  • SpeX: a medium-resolution infrared spectrograph
  • Subaru PFS: multi-object spectrograph in development for the Subaru telescope
  • TAIPAN: multi-object spectrograph with robot fiber-positioner
  • TripleSpec: near-infrared spectrograph on the Hale Telescope
  • WEAVE: multi-object spectrograph on the WHT
  • WFC3: general purpose camera/spectroscope on HST
  • Wide-field Multi-object Spectrograph: proposed instrument to detect baryon acoustic oscillations
  • WINERED: near-infrared non-cryogenic spectrograph
• spectrography: charting the strengths of different electromagnetic wavelengths
  • A-LIST: catalog of templates of H-band spectra for SPS
  • APOGEE: SDSS near-infrared survey of stars
  • ARIEL: planned space mission for exoplanet spectrography
  • blended spectra: an observed spectrum comprising light from multiple objects
  • CALIFA: spectroscopic map of 600 galaxies
  • California-Kepler Survey: follow-up to Kepler to determine stellar radii
  • cavity-enhanced absorption spectroscopy: passing a beam through a gas multiple times to amplify absorption lines
  • continuum: portion of a continuous spectrum not affected by a spectral feature
  • cross dispersion spectrograph: echelle spectrograph with additional disperser crosswise to the first
  • cryogenic spectroscopy: laboratory spectroscopy of materials cooled to cryogenic temperatures
  • damped Lyman alpha absorber: object producing broadened lines in a Lyman alpha forest
  • damping profile: mathematical shape that models some types of spectral line broadening
  • DEVILS: visible-light spectrographic survey of 56k distant galaxies
  • differential spectroscopy: analysis of the comparison of two spectrographs
  • diffuse interstellar bands: type of absorption bands seen in astronomical objects
  • double-line spectroscopic binary: spectroscopic binary star where a specific line shows up at two different wavelengths
  • eclipse mapping: using eclipse light curves to map surface features
  • electron shell: radius-level around an atomic nucleus at which electrons can orbit
  • Fabry-Pérot interferometer: type of chromatic-dispersing interferometer
  • fiber positioner: machine to set up fibers in multi-object spectrograph
  • fine structure: separate spectral lines due to electron spin and relativistic effects
  • FINESSE: planned space mission for exoplanet spectrography
  • forbidden line: spectral line that quantum mechanics disallows for the most part
  • Fraunhofer lines: dark lines discovered in the Sun's spectrum two centuries ago
  • Galaxy Evolution from Morphology and Spectral energy distributions: HST survey of galaxies with z in the range 0.2 to 1.2
  • GAMA: galaxy spectroscopy survey to roughly 1 Mpc
  • H3 Survey: spectroscopic survey of Milky Way halo stars
  • helium 1083 nm line: line useful in probing exoplanet atmospheres
  • heterodyne spectrometer: type of millimeter/submillimeter spectrometer
  • HITEMP: spectroscopic parameters for modeling gas optics
  • HRS: high resolution spectrography
  • hyperfine structure: spectral lines from magnetic and spin interactions between electrons and nucleus
  • imaging Fourier transform spectroscopy: Michelson-interferometer-based imaging spectroscopy
  • integral field spectrograph: spectrograph that captures images
  • Lick indices: defined set of spectral line indexes for stars
  • line shape function: function describing the shape of a spectral line
  • linearly variable filter: filter whose passband varies over one spatial dimension
  • Lock-In Amplified Externally Dispersed Interferometry: technique for precise RV measurement
  • Lyman-alpha forest: overlaid redshifted Lyman-alpha absorption lines on light from distant objects
  • Milky Way Mapper: SDSS spectrographic survey of Milky Way stars
  • multi-object spectrograph: device to record the spectrum of multiple targets simultaneously
  • radial velocity method: method of detecting exoplanets and binary companions
  • Rossiter-McLaughlin effect: effect of transit on visible spectrum of the star
  • signatures of formation: qualities of a body that suggest how it was formed
  • SINS: near-infrared study of distant luminous galaxies
  • sky subtraction: removing background radiation from a telescope observation
  • slitless spectrograph: spectrograph that does not utilize a slit
  • Sloan Digital Sky Survey: imaging survey of 500,000,000 objects in 35% of sky
  • Sobolev approximation: tractable model used in specific kinds of spectral line analysis
  • spaxel: like an image-pixel but with a SED for the location
  • spectral band: set of related, closely-packed spectral lines
  • spectral class: overall classification of stars based upon spectral features
  • spectral correlator: correlator that also functions as a spectrograph
  • spectral feature: recognizable feature of a spectrum
  • spectral line designation: labels used to identify spectral lines
  • spectral resolution: measure of a spectrograph's ability to resolve features of the spectrum
  • spectral signature: spectral characteristics indicating the emitting material and conditions
  • spectral type: classification of stars based upon spectral features
  • spectrograph: device to record the spectrum of incoming light
  • spectropolarimetry: measurement of light's polarization by wavelength
  • spectroscopic binary: binary star detected by movement indicated by Doppler shifts in the spectrum
  • Spectroscopic Properties of Cool Stars: analysis of spectroscopic data of 7000+ M and L stars
  • spectroscopy: measurement of light with various electromagnetic wavelengths
  • spectrum binary: binary star detectable because its spectrum looks like that of two stars
  • SPHEREx: all-sky spectral survey space-mission plan
  • SPLASH: survey of M31's Giant Stellar Stream
  • synthetic photometry: deriving photometry-style data from spectroscopy
  • synthetic spectrum: simulated spectrum, e.g., of a type of star
  • templates: mechanism to help classify many survey objects or events
  • transit spectroscopy: spectroscopy through an exoplanet's transit
  • transmission spectroscopy: spectrum of radiation passing through a substance
  • Voigt profile: mathematical shape that models spectral lines
• spectrometer: device to measure light by wavelength across its spectrum
  • ACES: a spectrometer used to view the corona during eclipses
  • ACIS: imaging spectrometer on Chandra X-ray telescope
  • Air-SPEC: a spectrometer used to view the corona during eclipses
  • ASPIRE: mechanism to stabilize observations from an airplane
  • Berkeley Extreme and Far-UV Spectrometer: 1990s UV spectrometer used on two Space Shuttle missions
  • CHIPS: small satellite to investigate ISM plasma
  • CONCERTO: spectrometer aimed at mapping the [CII] line
  • CTIS: imaging spectrometer using CT algorithm to sort out overlapping orders
  • DESHIMA: submillimeter spectrometer
  • EXCLAIM: planned balloon-borne 70-cm telescope with spectrometers
  • EXPRES: Yale HRS spectrometer aimed at exoplanet detection
  • spectrograph: device to record the spectrum of incoming light
  • spectrometry: measuring the strengths of different electromagnetic wavelengths
  • spectroscope: device to study the spectrum of incoming light
  • spectroscopy: measurement of light with various electromagnetic wavelengths
  • SPIRou: CFHT spectropolarimeter for exoplanet research
  • Tomographic Ionized-carbon Mapping Experiment: instrument in development to map the [CII] line
  • Tubingen Ultraviolet Echelle Spectrometer: 1990s UV spectrometer used on two Space Shuttle missions
  • UVSC Pathfinder: instrument to observe the Sun
• spectrometers
• disperser: prism, grating, or grism within a spectrometer
• grating: spectrometer component
• immersion grating: grating where light is within the material
• spectrometry: measuring the strengths of different electromagnetic wavelengths
  • spectrometer: device to measure light by wavelength across its spectrum
• Spectropolarimètre infrarouge (SPIRou): CFHT spectropolarimeter for exoplanet research
• spectropolarimeter: see spectropolarimetry
  • Zeeman effect: magnetic field influence on spectral lines
  • Zeeman-Doppler imaging: technique for imaging stellar magnetic fields
• Spectropolarimeter for Planetary Exploration
• SpeX: a medium-resolution infrared spectrograph
• spectropolarimetry: measurement of light's polarization by wavelength
• spectroscope: device to study the spectrum of incoming light
  • 4MOST: spectrograph in development for VISTA telescope
  • spectrograph: device to record the spectrum of incoming light
  • spectrometer: device to measure light by wavelength across its spectrum
  • spectroscopy: measurement of light with various electromagnetic wavelengths
  • TIM: planned balloon-borne 2 m telescope and spectrometer
• Spectroscopic and Photometric Landscape of Andromeda's Stellar Halo (SPLASH): survey of M31's Giant Stellar Stream
• spectroscopic binary: binary star detected by movement indicated by Doppler shifts in the spectrum
• Spectroscopic Imaging Survey in the Near-infrared with SINFONI (SINS): near-infrared study of distant luminous galaxies
• spectroscopic parallax: stellar distance determined through spectroscopy
• spectroscopic phase curve: see phase curve
• Spectroscopic Planet Observatory for Recognition of Interaction of Atmosphere (Hisaki): retired Japanese space ultraviolet telescope
• Spectroscopic Properties of Cool Stars: analysis of spectroscopic data of 7000+ M and L stars
• spectroscopic redshift: see photometric redshift
• spectroscopic retrieval: see retrieval
• Spectroscopic Survey Telescope (Hobby-Eberly Telescope): 10 meter telescope in Texas
• Spectroscopic Terahertz Airborne Receiver for Far-infrared Exploration (TIM): planned balloon-borne 2 m telescope and spectrometer
• Spectroscopic Terahertz observatory: see GUSTO
• Spectroscopic Time-Resolving Observatory for Broadband X-rays (STROBE-X): space X-ray telescope plan
• spectroscopy: measurement of light with various electromagnetic wavelengths
  • absorption: removal of photons from a beam of EMR
  • spectrograph: device to record the spectrum of incoming light
  • spectrometer: device to measure light by wavelength across its spectrum
  • spectroscope: device to study the spectrum of incoming light
• spectrum
• absorption line: dark line within a spectrum
• Balmer series: hydrogen lines for electrons settling from n > 2 to n = 2
• Brackett series: hydrogen lines for electrons settling from n > 4 to n = 4
• collisional broadening: line broadening due to nearby particles
• continuous absorption: the absorption of a whole section of a spectrum
• continuous spectrum: smooth spectrum or portion of spectrum with no lines
• Doppler broadening: broadening of spectral lines due to movement of the sources of photons
• emission line: narrow frequency-region of a spectrum with higher intensity
• extreme ultraviolet: electromagnetic radiation in the range of 10-124 nm
• extremely low frequency: electromagnetic radiation, frequency 3 Hz to 30 Hz
• far infrared: infrared radiation with wavelengths in the 30-450 μm range
• gamma rays: electromagnetic radiation, wavelength 10 picometers and less
• H-alpha: hydrogen line for electrons settling from n = 3 to n = 2
• H-beta: hydrogen line for electrons settling from n = 4 to n = 2
• high frequency: electromagnetic radiation, frequency 3-30 MHz
• Humphreys series: hydrogen lines for electrons settling from n > 6 to n = 6
• infrared: light with wavelength too long for our eyes to sense
• integral field unit: instrument to allow a spectrograph to capture data over a 2D field
• K-line: iron X-ray line
• line blanketing: so many bunched spectral lines that they cannot be distinguished
• line broadening: processes causing a spectral line to have width
• Lyman alpha: first line in the Lyman series
• Lyman beta: second line in the Lyman series
• Lyman series: hydrogen series from electrons settling from n > 1 to n = 1
• magnesium lines: spectral lines specific to magnesium
• microwave: electromagnetic radiation, frequency 300 MHz to 300 GHz
• mid infrared: infrared radiation with wavelengths in the 7.5-25 μm range
• natural broadening: line broadening due to uncertainty principle
• near infrared: electromagnetic radiation in the range of 750-2500 nm
• OIR: "band name" that means both visible light and infrared
• oxygen lines: spectral lines specific to oxygen
• Paschen series: hydrogen lines for electrons settling from n > 3 to n = 3
• Pfund series: hydrogen lines for electrons settling from n > 5 to n = 5
• radio: electromagnetic radiation, frequency 3 kHz to 300 GHz
• spectral line: dark or bright line in a spectrum
• spectral line designation: labels used to identify spectral lines
• spectral line shape: yields information about source
• spectral power distribution: function of power versus wavelength or frequency
• subradio: electromagnetic radiation, frequency below 3 kHz
• super low frequency: electromagnetic radiation, frequency 30 Hz to 300 Hz
• telluric line: absorption line in ground observation due to Earth atmosphere
• thermal bremsstrahlung: type of EMR produced by thin, hot plasma
• tremendously low frequency: presumably electromagnetic radiation, frequency below 3 Hz
• ultra low frequency: electromagnetic radiation, frequency 300 Hz to 3 kHz
• ultra-high-energy gamma rays: energetic gamma rays with more than 100 TeV photon energy
• ultraviolet: electromagnetic radiation, wavelength 10-400 nm
• UVOIR: a spectral "band name" covering UV, visible light, and IR
• very low frequency: electromagnetic radiation, frequency 3-30 kHz
• very-high-energy gamma rays: energetic gamma rays with 100 GeV to 100 TeV photon energy
• visible light: electromagnetic radiation that our eyes can sense
• water lines: spectral lines specific to water
• X-ray: electromagnetic radiation, wavelength 0.01 to 10 nanometers
• XEUV: electromagnetic radiation in the range of 0.15-124 nm
• spectrum analysis
• SPECTRE: an interactive spectrum analysis software package
• spectrum binary: binary star detectable because its spectrum looks like that of two stars
• spectrum synthesis
• Cloudy: code to model the effect of gas and plasma on spectra
• Spectrum-Roentgen-Gamma
• eROSITA: Russian/German space X-ray telescope launched in 2019
• Spectrum-X-Gamma (Spektr-RG): Russian-German X-ray observatory launched in 2019
• SPECULOOS: search for Earth-like exoplanets orbiting nearby dim stars
• SPECULOOS Northern Observatory: see SPECULOOS
• SPECULOOS Southern Observatory: see SPECULOOS
  • Paranal Observatory: ESO Atacama observatory with ESO VLT
• SPEDE: see SMART-1
• speed of light: fundamental constant measured as the speed at which light travels
  • refraction: redirection of light passing from one medium to another
  • refractive index: measure of how much a material slows down light
• speed of light in a vacuum (speed of light): fundamental constant measured as the speed at which light travels
• speed of sound (sound speed): speed at which compression waves traverse a gas
• SpeedyMC: see spectral energy distribution
• Spektr-R: 10 m space radio telescope
• Spektr-RG: Russian-German X-ray observatory launched in 2019
  • eROSITA: Russian/German space X-ray telescope launched in 2019
• SPEX
• SpeX: a medium-resolution infrared spectrograph
• SpeX: a medium-resolution infrared spectrograph
• SpeX: see IRTF
• SPF: see star formation
• SPH (smoothed-particle hydrodynamics): computational method for simulating fluid flows
  • Gasoline: an SPH code
• SPHERE: VLT instrument for imaging exoplanets
• SPHERE: see European Southern Observatory Very Large Telescope
  • BEAST: survey of B stars for possible exoplanets
  • Beta Pictoris b: super-Jupiter discovered in 2008
• sphere
• spheroid: sphere-like shape that is flattened or elongated
• SPHEREx: all-sky spectral survey space-mission plan
• spherical aberration: mis-focusing by spherically-curved mirrors and lenses
  • aberration: types of flaws in telescope images
• spherical astronomy (positional astronomy): calculation methods for relating sky position to position in space
  • astrometry: precise measurement of the position and movement of stars
• spherical cow: see back-of-the-envelope calculation
• spherical galaxy
• galaxy: gravitationally-bound group of stars
• spherical harmonic order
• angular power spectrum: method of characterizing the CMB
• spherical harmonics: harmonic functions on the surface of a sphere
  • CMB anisotropies: variations in the spectrum of the CMB
  • gravitational potential model: mathematical model of an astronomical body's gravitational field
  • multipole expansion: series expansion of a function over the surface of a sphere
• spherical mirror
• aspheric mirror: mirror with other than a spherical curvature
• spherical shell: see three dimensional model
• spheroid: sphere-like shape that is flattened or elongated
  • paraboloid: circularly-symmetric 3D surface based on parabola
• spheroidal (dwarf spheroidal galaxy): spheroidally-shaped dwarf galaxy lacking star formation
• SPI: see INTEGRAL
• SPICA: plan for a future space IR telescope
• SPICA: see CHARA
• SPICAM: see Mars Express
• SPICAV: see Venus Express
• SPICE: see Solar Orbiter
• spicule: small temporary jet from Sun's surface
  • Sun surface features: features on the Sun's surface
• SPIDER: 2015 balloon-borne observatory to observe CMB polarization
  • Taurus­: balloon-borne polarimeter to study the CMB
• spin: an angular-momentum quantum number
• spin: see particle
  • electron orbital: a nucleus's "locations" where an electron can orbit
  • Pauli exclusion principle: fermions in a quantum system cannot have identical quantum numbers
  • quantum number: number representing a conserved quantity
  • supersymmetry: extension to standard model of particle physics
• spin quantum number (spin): an angular-momentum quantum number
  • electron orbital: a nucleus's "locations" where an electron can orbit
• spin-down
• pulsar characteristic age: approximate age determination of a pulsar based upon rotation rate
• spin-down energy
• magnetic dipole braking: the effect of a reduction in the spinning of a magnetic field
• spin-down luminosity: pulsar's energy extracted from slowing rotation
  • magnetic dipole braking: the effect of a reduction in the spinning of a magnetic field
• spin-down time
• magnetic dipole braking: the effect of a reduction in the spinning of a magnetic field
• spin-down timescale
• magnetic dipole braking: the effect of a reduction in the spinning of a magnetic field
• spin-flip transition: see 21-cm line
• spin-orbit resonance: see tidal locking
• Spindle Galaxy: disk galaxy for which we have an edge-on view
• spinel
• CAI: calcium/aluminum specs in chondrites
• spinning dust: see spinning dust emission
  • anomalous microwave emission: component of microwave background discovered in the 1990s
• spinning dust emission: source of microwave signal
• spiral
• Andromeda: spiral galaxy in the Local Group
• bar: central feature of some spiral galaxies
• Comet Galaxy: unique spiral galaxy in cluster Abell 2667
• ESO 137-001: barred spiral galaxy in the Abell 3627 cluster
• grand design spiral galaxy: spiral galaxy with two just two arms that are well-defined
• IC 342: spiral galaxy in the Council of Giants
• Large Magellanic Cloud: somewhat irregular satellite galaxy of the Milky Way
• M64: nearby dusty galaxy
• Messier 100: easily-observed spiral galaxy
• Messier 106: spiral galaxy with maser
• Messier 74: easily-observed spiral galaxy
• Messier 77: easily-observed spiral galaxy
• Milky Way: our galaxy
• NGC 253: spiral galaxy 11 million light-years away
• NGC 2770: spiral galaxy that has shown a number of supernovae
• NGC 3314: a pair of galaxies aligned with us
• NGC 6946: face-on spiral galaxy
• NGC 7331: spiral galaxy without a bar
• NGC 7469: spiral galaxy with AGN outflow
• Pinwheel Galaxy: easily-observed spiral galaxy
• radial mixing: tendency of disk galaxy stars to change their orbital radius
• Small Magellanic Cloud: dwarf galaxy in the Local Group
• Sombrero Galaxy: striking spiral galaxy with very large bulge
• Spindle Galaxy: disk galaxy for which we have an edge-on view
• spiral arm: long, winding visible structure within a spiral galaxy
• spiral density wave: spiral structure that can form in disks
• Triangulum Galaxy: small spiral galaxy in the Local Group
• Tully-Fisher relation: relation between spiral galaxy luminosity and line width
• warp: bend in the otherwise-flat disk of a galaxy
• Whirlpool Galaxy: easily-observed spiral galaxy
• spiral arm: long, winding visible structure within a spiral galaxy
  • galaxy: gravitationally-bound group of stars
  • grand design spiral galaxy: spiral galaxy with two just two arms that are well-defined
  • spiral galaxy: flat galaxy with spiraling arms
• spiral density wave: spiral structure that can form in disks
  • galaxy: gravitationally-bound group of stars
  • gravitational instability model: model for the formation of giant planets
  • planetary migration: change in planet's orbit
• spiral galaxies
• hypergalaxy: sizeable spiral galaxy with satellites
• spiral galaxy: flat galaxy with spiraling arms
  • disk galaxy: circular, relatively flat galaxy such as a spiral galaxy
  • galaxy: gravitationally-bound group of stars
  • galaxy classification: morphological classification of galaxies
  • lenticular galaxy: disk galaxy that has no spirals
  • NGC 7331: spiral galaxy without a bar
  • spiral arm: long, winding visible structure within a spiral galaxy
  • stellar dynamics: stars' gravitational interaction
• spiral galaxy formation: see spiral galaxy
• spiral nebula
• Kapteyn universe: early 20th century model of the universe centered on the Milky Way
• spiral structure
• grand design spiral galaxy: spiral galaxy with two just two arms that are well-defined
• spiral density wave: spiral structure that can form in disks
• spiral galaxy: flat galaxy with spiraling arms
• SPIRE: see Herschel Space Observatory
  • BLAST: balloon-borne 1.8-m submillimeter telescope
  • Herschel Stripe 82 Survey: 70 square-degree survey of galaxies redshifted 1.8 to 3.5
  • imaging Fourier transform spectroscopy: Michelson-interferometer-based imaging spectroscopy
• Spirit: see Mars Exploration Rover
• SPIRIT III: see Midcourse Space Experiment
• SPIRITS: Spitzer survey designed to find transients
• SPIRou: CFHT spectropolarimeter for exoplanet research
• SPIRou Legacy Survey: see SPIRou
• Spitzer (Spitzer Space Telescope): retired infrared space telescope
  • GOODS: survey combining data from different sources on very distant objects
  • IRAC Shallow Survey: Spitzer survey of moderately wide field
  • SPIRITS: Spitzer survey designed to find transients
  • Spitzer Extended Deep Survey: survey of galaxy mass and black holes through life of the universe
  • Spitzer HETDEX Exploratory Large Area Survey: Spitzer-based survey of galaxies
  • Ultimate Spitzer Phase Curve Survey: investigation of exoplanet atmospheres
• Spitzer Extended Deep Survey: survey of galaxy mass and black holes through life of the universe
• Spitzer Extragalactic Representative Volume Survey: infrared survey of some well-studied fields
• Spitzer HETDEX Exploratory Large Area Survey: Spitzer-based survey of galaxies
• Spitzer Infrared Intensive Transient Survey (SPIRITS): Spitzer survey designed to find transients
• Spitzer IRAC Shallow Survey (IRAC Shallow Survey): Spitzer survey of moderately wide field
• Spitzer ISS (IRAC Shallow Survey): Spitzer survey of moderately wide field
• Spitzer Space Telescope: retired infrared space telescope
  • Spitzer Extragalactic Representative Volume Survey: infrared survey of some well-studied fields
• Spitzer Warm Mission: see Spitzer Space Telescope
• SPLASH: survey of M31's Giant Stellar Stream
• splashback
• cluster radius: radius of a galaxy cluster
• splashback radius: see cluster radius
• SPOCK: code to determine stability of orbits
• SPOCS (Spectroscopic Properties of Cool Stars): analysis of spectroscopic data of 7000+ M and L stars
• SPOL: see MMT
• spontaneous emission: see emission
  • Einstein coefficients: a substance's probabilities of emission and absorption
• spontaneous symmetry breaking: see symmetry breaking
• SPRAT: see Liverpool Telescope
• SPRINT-A (Hisaki): retired Japanese space ultraviolet telescope
• Sprite
• Starshot: plan for mission to fly by Alpha Centauri
• SPS (solar powered satellite): concept for a satellite to collect and transfer energy to Earth
• SPS (stellar population synthesis): using spectral characteristics of galaxies to characterize their stellar populations
• SPS: see rare designator prefixes
  • A-LIST: catalog of templates of H-band spectra for SPS
• SPS code (stellar population synthesis code): software to perform stellar population synthesis
• SPT (South Pole Telescope): a millimeter/microwave telescope at South Pole
  • South Pole Station: science station at the South Pole
• SPT-3G: see South Pole Telescope
• SPT-CL: see South Pole Telescope
• SPT-SZ: see South Pole Telescope
• SPTpol: see South Pole Telescope
• SQM (sky quality meter): device to measure the brightness/magnitude of the sky itself.
  • neutron star: stellar remnant consisting entirely of solar masses of neutrons
• square arcminute: see solid angle
• square degree: see solid angle
• Square Kilometre Array: planned radio telescope with square-kilometer collecting area
• Square Kilometre Array Observatory (Square Kilometre Array): planned radio telescope with square-kilometer collecting area
• Square Kilometre Array Organization: see Square Kilometre Array
• square radian: see solid angle
• squark: see supersymmetry
• SQUID: very sensitive magnetometer
• SQUID (superconducting quantum interference device): type of very sensitive magnetometer using Josephson junctions
  • Cryogenic Dark Matter Search: a search for a candidate dark matter particle
  • Cryogenic Rare Event Search with Superconducting Thermometers: a search for a candidate dark matter particle
• Squid Galaxy (Messier 77): easily-observed spiral galaxy
• SR (special relativity): physics explaining how the speed of light can be constant
• SR: see rare designator prefixes
• SR: see relativity
• SRG (Spektr-RG): Russian-German X-ray observatory launched in 2019
  • eROSITA: Russian/German space X-ray telescope launched in 2019
• SRGA: see Spektr-RG
• SRGE: see eROSITA
• SRON (Space Research Organization of the Netherlands): national research institution
• SRR: see MDR/SRR
• SRS: see EnVision
• SRS: see rare designator prefixes
• SRT (Sardinia Radio Telescope): Italian large single-dish radio telescope
• SS (symbiotic binary): giant star transferring mass to a somewhat distant companion
• SS: see Case-Hamburg Survey
• SS: see rare designator prefixes
• SS 433: first microquasar discovered
• SSA: see rare designator prefixes
• SSA22
• proto-cluster: newly-formed galaxy cluster
• SSB (Space Studies Board): National Academy of Sciences unit re astronomy an research via spacecraft
• SSC (synchrotron self-Compton): charged particle cloud scattering its own synchrotron-produced photons
• SSC: see Stardust
• SSD: see particle spectrometer
• ssDNA: DNA without the double strand
• SSE: see BSE
• SSE: see ephemeris
• SSFR: see star formation rate
• SSI (Space Studies Institute): organization promoting interest in and use of space technology
• SSI: see Ariel 5
• SSI: see Galileo
• SSI: see Mars Polar Lander
• SSI: see Phoenix
• SSM: see AstroSat
  • stellar structure: the presumed internal structure of stars
• SSN (United States Space Surveillance Network): US survey-effort of space objects of interest
• SSO (Siding Spring Observatory): observatory in New South Wales, Australia
• SSO (solar system object): the Sun, solar system planets, minor planets, comets, and moons
• SSO: see SPECULOOS
  • GOTO: telescope array to follow up gravitational wave signals
  • National Solar Observatory: US government sponsored solar observatory
• SSP: set of stars born at the same time with the same metallicity
• SSP: see Cassini
• SSP: see Subaru PFS
  • A-LIST: catalog of templates of H-band spectra for SPS
• SSP Survey: see Subaru PFS
• SSRS (Southern Sky Redshift Survey): 1980s/1990s redshift survey of southern galaxies
• SSRS2: see Southern Sky Redshift Survey
  • UZC-SSRS2 Group Catalog: 2002 catalog of galaxy groups
• SSS (SuperCOSMOS Sky Survey): survey of stars and galaxies from legacy plates
• SSS (Swope Supernova Survey): survey of low-redshift Type Ia SN light curves
• SSS: see Catalina Sky Survey
• SSS: see HEAO-2
• SSSB: solar system body smaller than a dwarf planet
  • minor planet: lesser solar system body without comet characteristics
• SSSBs
• solar system object: the Sun, solar system planets, minor planets, comets, and moons
• SSSPM: see SuperCOSMOS Sky Survey
• SST (Hobby-Eberly Telescope): 10 meter telescope in Texas
• SST (Space Surveillance Telescope): 3.5-m US telescope to discover and monitor objects in space
• SST (Spitzer Space Telescope): retired infrared space telescope
• SST: see Cherenkov Telescope Array
• SST: see Roque de los Muchachos Observatory
  • GOALS: across-spectrum observation of 200 LIRGs
  • LINEAR: survey of near-Earth objects
  • Spitzer Extragalactic Representative Volume Survey: infrared survey of some well-studied fields
  • THEMIS: set of satellites studying the Earth's magnetic field
• SSV: see rare designator prefixes
• ST: see double star designation
• ST: see rare designator prefixes
• St (Stokes number): measure of a particle's tendency to follow the flow of a fluid
• Stömgren radius: see Strömgren sphere
• Stability of Planetary Orbital Configurations Klassifier (SPOCK): code to determine stability of orbits
• stability radius: see isolation mass
• stable isotope: see isotope
• stacking: combining images of the same object
  • shift-and-add: common speckle-suppression technique
  • speckle imaging: method of combining short-term images to yield better resolution
• Stampede: research supercomputer at U. Texas
• standard and normal evolution
• AGN accretion: an SMBH's accretion, such as powers AGNs/quasars
• standard atomic weight: see element
• standard Big Bang: see Big Bang
• standard candle: astronomical object whose brightness can be determined
• standard cosmology: see alternative cosmologies
• standard deviation (sigma): indication of the confidence level of an experiment
  • error bar: feature of a graph to indicate accuracy
  • RMS: square root of the average of the squares of some values
  • velocity dispersion: statistical dispersion of velocities of a group of objects
• standard error of the mean
• error bar: feature of a graph to indicate accuracy
• standard gravitational parameter: a body's mass times the universal gravitational constant
• standard gravity: see surface gravity
• standard main sequence (zero-age main sequence): describes stars that just began hydrogen fusion
• standard model: model of elementary particles including quarks
• standard model (Lambda-CDM model): Big-Bang cosmological model with a cosmological constant and cold dark matter
  • cosmological model: model of the workings and history of the universe
  • fiducial: taken as a standard
  • flavor: subtype of some type of particle
  • quark: type of elementary particle incorporated in protons and neutrons
• standard model of a flare: description of how solar flares function
• standard model of particle physics (standard model): model of elementary particles including quarks
  • axion: proposed light, electrically neutral elementary particle
  • supersymmetry: extension to standard model of particle physics
• standard reduction potential: see reduction potential
• standard ruler: astronomical phenomenon whose size can be determined
  • baryon acoustic oscillations: density fluctuations stemming from acoustic waves in the early universe
• standard siren: transient whose gravitational waves indicate a specific distance
• standard solar model
• stellar structure: the presumed internal structure of stars
• standard source: see photometry
• standard star (telluric star): star of known spectrum used for calibration
• standard star: see photometry
• Stanford University
• Kavli Institute: any of a number of science institutes supported by Kavli Foundation
• star: astronomical body shining from fusion energy
  • 16 Cygni: triple star system with detected exoplanet
  • 2M1207: brown dwarf with possible exoplanet
  • AB Aurigae: YSO with disk apparently forming planets
  • AB Pictoris: K-type star with possible planet
  • Achernar: ninth-brightest star in the sky
  • AD Leonis: active red dwarf
  • Algol: a multiple-star system demonstrating effects of mass transfer
  • Alpha Centauri: nearest star system
  • Arcturus: fourth brightest star in the sky
  • AU Microscopii: nearby star with disk and planets
  • Barnard's Star: nearby red dwarf
  • Beta Centauri: second brightest star in Centaurus
  • Betelgeuse: second brightest star in constellation Orion
  • Black Widow Pulsar: binary system consisting of a pulsar and small companion
  • Canopus: second brightest star in the sky
  • Capella: brightest star in Auriga
  • DM Tau: nearby T-Tauri star
  • DQ Tau: young binary star system
  • EF Eridani: binary star including a substellar object
  • Elias 2-27: much-studied YSO
  • Epsilon Eridani: third nearest visible star system in sky
  • Epsilon Indi: nearby star system including two brown dwarf companions
  • Eta Carinae: variable star
  • G239-25: nearby red dwarf with brown dwarf companion
  • GG Tau: much-studied quadruple star system
  • Giclas 29-38: white dwarf variable star of interest
  • HD 114762: star system thought to host the first detected exoplanet
  • HD 133131: binary star system with exoplanets
  • HD 163296: YSO with gaps in its protoplanetary disk
  • HD 169142: protostar with planet
  • HL Tau: much-studied T-Tauri star
  • HR 8799: star with four directly-imaged exoplanets
  • Hulse-Taylor Binary: binary system consisting of a pulsar and neutron star
  • J1407: star eclipsed by a body with a ring system
  • J1713+0747: binary system with millisecond pulsar and white dwarf
  • Kapteyn's Star: nearby M dwarf
  • Kepler-79: star with four super-puff planets
  • KIC 8462852: star with unusual variations
  • Lacaille 9352: red dwarf that is the twelfth nearest star system
  • Lalande 21185: nearby red dwarf
  • LB-1: binary star with evidence of a black hole
  • LHS 1140: red dwarf with rocky planet in its habitable zone
  • Luhman 16: nearby binary brown dwarf
  • Luyten 726-8: nearby binary star system
  • MWC 758: protostar with spiral disk
  • PDS 70: T-Tauri star with protoplanetary disk and protoplanet
  • Procyon: brightest star in Canis Minor
  • PSR 1257+12: pulsar with first discovered planet system
  • PSR B0950+08: young pulsar
  • PSR B1259-63: pulsar part of an eclipsing binary
  • PSR J2145-0750: binary system consisting of a pulsar and white dwarf
  • Rigel: brightest star in constellation Orion
  • Ross 154: nearby red dwarf
  • Ross 248: nearby red dwarf
  • RS Ophiuchi: Milky Way recurrent nova
  • RXJ1615: protostar with transition disk showing rings
  • Scholz's Star: nearby binary star with red dwarf and brown dwarf
  • Sirius: brightest star in the sky
  • SMSS J2003-1142: unusual giant star in Milky Way halo
  • SS 433: first microquasar discovered
  • Sun: star at center of solar system
  • T Pyxidis: well-known recurrent nova
  • T Tauri: variable star taken as example of young star
  • Teegarden's Star: nearby red dwarf
  • TRAPPIST-1: red dwarf with exoplanets within the habitable zone
  • TW Hydrae: nearest T-Tauri star
  • V339 Delphini: 2013 nova showing lithium synthesis
  • Vega: brightest star in constellation Lyra
  • VY Canis Majoris: extremely large red hypergiant
  • WD J0651+2844: binary pair of closely-orbiting white dwarfs
  • WISE 0855-0714: nearby brown dwarf
  • WISE 1506+7027: nearby brown dwarf
  • WISE 1534-1043: nearby brown dwarf with high proper motion
  • Wolf 359: nearby red dwarf
  • WR 104: Wolf-Rayet star surrounded by spiral nebula
  • WR 140: Wolf-Rayet star that produces much dust
  • ZTF J1539+5027: binary star of two white dwarfs with tight orbit
• STAR Academy: Arecbio pre-college program
• star and planet formation: see star formation
• star catalog: see astronomical catalog
  • astrometry: precise measurement of the position and movement of stars
• star catalogue: see astronomical catalog
• star class
• luminosity class: classification of size/luminosity of stars
• star cloud: lighter region of the night sky consisting of a high density of stars
• star cluster (stellar cluster): group of stars apparently formed by a single cloud
  • field star: star that is not part of a star cluster
• star clusters
• Basel Open Cluster Catalogue: list of open clusters
• Berkeley Open Cluster Catalogue: list of open clusters
• Bologna Catalog of Globular Clusters: catalog of globular clusters in M31
• Collinder Catalog: 1930s catalog of 471 open clusters
• Czernik Catalog: list of open clusters
• Dolidze-Dzimselejsvili Catalogue: list of 11 open clusters
• Dynamical Analysis of Nearby Clusters: survey of stars in stellar clusters
• field star: star that is not part of a star cluster
• globular cluster: spherical group of stars orbiting a galaxy
• Index Catalog: 1895 catalog of galaxies, star clusters, and other nebulae
• King Catalog: list of 21 open clusters
• lithium depletion boundary: line on HRD dividing stars with lithium and those without
• Lund Catalogue of Open Clusters: list of open clusters
• Melotte Catalog: 1915 catalog of open and globular clusters
• Messier Catalog: catalog of astronomical objects to avoid when looking for comets
• MOCCA: code to model the evolution of stellar clusters
• moving group: observed group of stars with similar motion
• moving-cluster method: method of measuring distance to a nearby star cluster
• New General Catalogue: 1888 catalog of galaxies, star clusters, and other nebulae
• open cluster: group of stars within a galaxy apparently formed by a single cloud
• Palomar Globular Clusters: list of 15 globular clusters found in POSS plates
• red supergiant cluster: stellar cluster with multiple red supergiants
• S-Star Cluster: stellar cluster at the center of the Milky Way
• SSP: set of stars born at the same time with the same metallicity
• stellar association: like a large open cluster but even less tightly bound
• stellar cluster: group of stars apparently formed by a single cloud
• stellar dynamics: stars' gravitational interaction
• stellar stream: long group of co-moving stars
• WIYN Open Cluster Study: study begun in 2000 using the WIYN 3.5m Telescope
• star count: surveys of stars counting them according to some criteria
• star formation: theorized collapse of gas and dust into stars
  • AIM-CO: survey of CO from star-forming epoch
  • Bok globule: dense molecular cloud
  • Butcher-Oemler effect: observation of more blue galaxies at z > 0.3
  • carbon monoxide: compound of carbon and oxygen, one atom each
  • cloud fragmentation: clumping in clouds due to gravitational instability
  • cold gas: gas cool enough to form galaxies and stars
  • COMPLETE Survey: survey of star forming regions
  • CONCERTO: spectrometer aimed at mapping the [CII] line
  • COPSS: survey of CO from star forming epoch
  • dark nebula: cloud that obscures stars behind it
  • dense core: dense molecular cloud
  • dense core mass function: function describing range of masses of dense cores
  • diffuse emission: electromagnetic radiation not confined to a point source
  • dusty galaxy: galaxy including substantial dust
  • emission line galaxy: a galaxy type characterized by emission lines
  • epoch of galaxy formation: before z=1, when many galaxies formed
  • evaporating gas globule: very small dense cloud of hydrogen and dust
  • filament: linear volume of high molecular gas density within a galaxy
  • galactic wind: wind of charged particles out of some galaxies
  • galaxy merger: combination of galaxies upon collision
  • galaxy strangulation: galaxy star formation stopped by a lack of incoming gas
  • giant molecular cloud: interstellar gas cloud with molecules, thousands of solar masses
  • Gould's Belt: ring of stars around the sky
  • Gould's Belt Distances Survey: survey of parallax distances to Gould's Belt YSOs
  • Hα survey: survey looking for the Hα line, typically to find star formation
  • Herbig-Haro object: type of glowing nebula near protostars
  • HII region: cloud of partially-ionized atomic hydrogen
  • infrared dark cloud: molecular cloud not emitting nor transmitting infrared
  • inside-out growth: tendency of galaxy star formation to spread from the center
  • jellyfish galaxy: galaxy with a gas tail including star formation
  • Kennicutt-Schmidt law: relation between gas density and star formation rate
  • KMOS3D: survey of galaxies before to after peak star formation
  • Lyman-alpha emitter: redshifted galaxy emitting the Lyman alpha line
  • Millimeter-wave Intensity Mapping Experiment: project to map CO and [CII]
  • molecular cloud: interstellar gas cloud that includes molecules
  • Molecular Deep Field: survey of molecular lines in Hubble Deep Field
  • peak star-formation epoch: around 10 billion years ago when star formation peaked
  • PEP: survey aimed at star formation in early times
  • PHIBSS: survey of CO in distant galaxies
  • photodissociation region: cloud of partially-ionized atomic hydrogen
  • post-starburst galaxy: galaxy indicating star formation some time back
  • protostar: contracted mass of gas that will become a star
  • quenched galaxy: galaxy currently producing minimal stars
  • star formation feedback: mechanisms whereby star formation regulates its own rate
  • star formation history: star formation rate as a function of time
  • star formation rate: rate at which material such as gas is turned into stars
  • star-formation rate stellar-mass ratio: ratio between a galaxy's stellar mass and its SF rate
  • star-forming region: area forming stars and/or ready for star formation
  • starburst galaxy: galaxy forming stars at a very high rate
  • STARBURST99: software to simulate star-forming galaxies
  • STARFORGE: star formation simulation code
  • stellar birth rate function: function describing the birth rate of stars by mass
  • stellar population synthesis code: software to perform stellar population synthesis
  • surface density: quantity such as mass per unit area
  • Taurus Molecular Cloud 1: nearby star-forming region
  • Tomographic Ionized-carbon Mapping Experiment: instrument in development to map the [CII] line
  • ultraluminous infrared galaxy: a galaxy emitting a more far infrared than an LIRG
• star formation efficiency: see star formation rate
• star formation feedback: mechanisms whereby star formation regulates its own rate
• star formation history: star formation rate as a function of time
• Star Formation in Gaseous Environments (STARFORGE): star formation simulation code
• star formation law (Kennicutt-Schmidt law): relation between gas density and star formation rate
• star formation main sequence (galaxy main sequence): relation between galaxies' star formation and stellar mass
• star formation rate: rate at which material such as gas is turned into stars
  • galaxy main sequence: relation between galaxies' star formation and stellar mass
  • peak star-formation epoch: around 10 billion years ago when star formation peaked
  • star formation history: star formation rate as a function of time
• star formation rate density: see star formation rate
  • star formation history: star formation rate as a function of time
• star forming filament (filament): linear volume of high molecular gas density within a galaxy
• star system: a gravitationally bound set of a few stars
  • multiple star system: system of two or more stars co-orbiting
  • solar system: the Sun and what's gravitationally bound to it
• star type
• A-type star: star with spectral characteristics of around 8500 K
• Am star: A-type star with metallic lines
• anomalous X-ray pulsar: X-ray pulsars with no high-mass companion
• Ap star: peculiar type of A star
• astrometric binary: binary star system detected by observing the movement of a star
• asymptotic giant branch: a second stage of helium burning in some stars
• B-type star: star with spectral characteristics of around 10000-30000 K
• BA supergiant: very bright giant star
• barium star: star showing unexpected barium lines
• Be star: early star with Balmer emission lines
• binary companion: one of the two stars of a binary star
• binary neutron star: two neutron stars co-orbiting
• binary star: system of two stars co-orbiting
• blue horizontal branch: blue end of the horizontal branch
• brown dwarf: star-like object with less mass than a star
• carbon star: star with more carbon than oxygen in its atmosphere
• cataclysmic variable star: star whose magnitude is much brighter on occasion
• Cepheid variable: type of star that varies with a constant period
• chemically peculiar star: star with SED showing presence metals unusual for stars
• collapsar: neutron star or stellar black hole
• common envelope: binary star system surrounded by a single gas cloud
• compact object: dense astronomical body such as white dwarf or denser
• contact binary: binary stars orbiting so close they are touching
• dark star: theoretical star-like object heated by dark-matter annihilation
• double star: two stars close together in the sky
• double-line spectroscopic binary: spectroscopic binary star where a specific line shows up at two different wavelengths
• eclipsing binary: binary star system detected by variations in magnitude
• ellipsoidal variable: binary star elongated by gravity
• emission-line star: general term for a star exhibiting stronger-than-usual emission lines
• exotic star: term for theoretical stars not made of atoms/ions
• F-type star: spectral class of star a bit hotter than then Sun
• failed binary: like a binary star but one with less mass than a star
• FGK star: a star of the "middle" spectral classes, F, G, and K
• field star: star that is not part of a star cluster
• fixed star: star that does not change position in the celestial sphere
• FU Orionis star: type of variable pre-main-sequence star
• G-type star: stars spectrally similar to the Sun
• giant star: star larger than main sequence stars
• guide star: star used to assist in astronomical observation
• heartbeat star: type of binary star that produces pulsed light
• helium star: O or B star with very strong helium lines
• Herbig AeBe star: type of pre-main-sequence star more massive than a T-Tauri star
• high-B radio pulsar: pulsar with a strong magnetic field
• high-velocity star: star moving noticeably faster than neighbors
• Honda-like star: very-low-metallicity star with r-process elements
• horizontal branch: a second "giant" stage in the evolution of some main sequence stars
• hypergiant: extremely bright stars
• hypermassive neutron star: neutron star massive enough to collapse
• hypervelocity star: star moving very much faster than usual
• K-type star: spectral class of star a bit cooler than the Sun
• L-type star: spectral type of star cooler than an M-type star
• Lambda Boötis star: peculiar star with metallicity only with lighter elements
• low mass star: star with less than half a solar mass
• luminous blue variable: type of extremely bright variable stars
• M dwarf: small, cool main-sequence star in stellar class M
• M-type star: spectral class of star with a temperature in the vicinity of 2500 K
• magnetar: neutron star with a strong magnetic field
• main sequence star: star burning hydrogen into helium in its center
• multiple star system: system of two or more stars co-orbiting
• neutron star: stellar remnant consisting entirely of solar masses of neutrons
• O-type star: star with spectral characteristics of above 30000 K
• O5 spectral type: spectral type of star with a temperature of about 45000 K
• OB star: a hot star with class O or early B
• OH/IR source: AGB star with strong OH maser
• optical double: double star where the two are not gravitationally bound
• PG 1159 star: star in transition between planetary nebula and white dwarf
• pole star: star aligned with a planet's axis of rotation
• post-common-envelope binary: binary star system showing unusual stellar evolution
• post-main-sequence star: star evolved beyond its main sequence phase
• pre-main-sequence star: star not yet with a nuclear reaction
• pulsar: type of astronomical body with EMR in regular cycles of seconds or less
• pulsating star: variable star that varies through energy pulses
• radio star: star emitting much radio
• red clump: like horizontal branch but at one temperature
• red dwarf: small, cool main-sequence star
• red giant: very bright red star
• red-giant branch: the first red-giant phase of post-main-sequence stellar evolution
• RR Lyrae variable: star with periodic variation often in globular clusters
• S-type star: type of star with lines indicating zirconium
• shell star: type of star with broad and narrow absorption lines
• slowly-pulsating B-star: B-star with pulsation periods of more than half a day
• spectroscopic binary: binary star detected by movement indicated by Doppler shifts in the spectrum
• spectrum binary: binary star detectable because its spectrum looks like that of two stars
• stellar remnant: leftovers from a mainstream star
• stripped star: star with substantial material removed by a binary companion
• subdwarf: star less bright than the main sequence given its spectral class
• subgiant: slightly larger than normal star
• substellar object: star-like object with less mass than a star
• supergiant: very large giant star
• supermassive star: star more massive than stars normally form
• supernova progenitor: the star or star system that produces a supernova
• symbiotic binary: giant star transferring mass to a somewhat distant companion
• T-Tauri star: type of variable pre-main-sequence star
• T-type star: brown dwarf with a temperature in the vicinity of 1000 K
• technetium star: star showing technetium absorption lines
• telluric star: star of known spectrum used for calibration
• Thorne-Żytkow object: giant star with a neutron star at its center
• ultracool dwarf: star or brown dwarf cooler than M7 class
• variable star: star that varies in magnitude
• visual binary: binary star system in which both stars can be seen
• weak-line star: star with faint spectral lines compared to its spectral class
• white dwarf: stellar remnant largely of electron degenerate matter
• wide binaries: binary stars thousands of AU apart
• Wolf-Rayet star: type of star with broad emission bands
• X-ray binary: binary star emitting X-rays
• X-ray pulsar: pulsar producing X-rays from accretion
• Y-type star: brown dwarf with a temperature less than 700 K
• young stellar object: early stage of a star
• star-formation rate stellar-mass ratio: ratio between a galaxy's stellar mass and its SF rate
• star-forming galaxy: see galaxy main sequence
• star-forming galaxy: see starburst galaxy
• star-forming radio galaxy: see radio galaxy
• star-forming region: area forming stars and/or ready for star formation
  • Cygnus-X: well-studied massive SF region
  • NGC 2363: low-metallicity SF region
  • NGC 346: open cluster in SMC
  • Orion Molecular Cloud Complex: group of molecular clouds with star-forming regions
  • Rho Ophiuchi Cloud Complex: nebula that is a nearby star-forming region
  • SBS 0335-052: blue compact galaxy
  • Serpens Cloud: molecular cloud with SF regions
  • Taurus Molecular Cloud 1: nearby star-forming region
  • Taurus-Auriga Complex: nearby star-forming region
  • Trapezium Cluster: open cluster of stars in Orion Nebula
  • W51: cloud complex radio source
• STAR-X: plan for a future X-ray space telescope
• StarBug: see TAIPAN
• starburst: see starburst galaxy
  • AzTEC-3: very distant starburst galaxy
  • HFLS3: very distant starburst galaxy
  • M82: nearby starburst galaxy
  • NGC 253: spiral galaxy 11 million light-years away
• starburst galaxy: galaxy forming stars at a very high rate
  • star formation rate: rate at which material such as gas is turned into stars
• STARBURST99: software to simulate star-forming galaxies
• StarChip
• Starshot: plan for mission to fly by Alpha Centauri
• Stardust: space mission that collected and returned comet coma dust
• stardust: see presolar grain
• STARE: array of radio telescopes monitoring radio transients
• STARE Telescope: see Teide Observatory
  • Trans-Atlantic Exoplanet Survey: 2000s exoplanet-search survey using three telescopes
• STARE2: see STARE
• starfield: see asterism
• STARFIRE (TIM): planned balloon-borne 2 m telescope and spectrometer
• STARFORGE: star formation simulation code
• Stargazer: see Orbiting Astronomical Observatory
• Stark broadening: see Stark effect
• Stark effect: electric field influence on spectral lines
• Starlight Attenuation & Reddening Survey of Multiple Occulting Galaxies (STARSMOG): survey of dust in galaxies
• starquake: see quake
• stars
• 8 pc: survey of stars within 8 parsecs, using coronagraph
• A-LIST: catalog of templates of H-band spectra for SPS
• accretion: enlargement of an astronomical body by gravitationally attracting additional mass
• accretion disk: disk around an astronomical body of material that is accreting
• age-metallicity relation: older stars generally have lower metallicity
• age-velocity-dispersion relation: relation between stellar age and peculiar velocity
• Aitken Double Star Catalogue: 1932 catalog with both multiple-star systems and non-orbiting double stars
• All-Sky Compiled Catalogue: 2001 catalog compiled from modern sources
• American Association of Variable Star Observers: organization of amateur observers of variable stars
• APASS: down to 16 magnitude
• asterism: easily recognizable star pattern
• asteroseismology: study of stars through analysis of their pulsation
• Astrographic Catalog: historical star catalog of the whole sky to magnitude 11
• Astronomische Gesellschaft Katalog: 19th/20th century astrometric catalog
• ATLAS Stellar Model: computer model of a stellar photosphere
• atmosphere: gas surrounding astronomical object
• Balmer jump: abrupt change in stellar spectrum at the Balmer series wavelength limit
• BaSTI: database relating isochrones to stellar parameters
• BATC: photometric survey of Milky Way stars
• Bayer designation: star designation consisting of a Greek letter and constellation name
• BCool: project studying stellar magnetism
• Bibliographic Catalog of Variable Stars: listing of references to variable stars
• bipolar outflow: streams of matter from the poles of a protostar
• Bonner Durchmusterung Catalog: well-known astrometric catalog from late 1800s
• Boss General Catalog: 1936 catalog of 30,000 stars
• Bright Star Catalog: early 20th century catalog of 9000 stars
• Bruce Proper Motion Survey: 1941 southern-hemisphere survey catalog of Luyten's
• BT-Settl: model atmosphere of small stars and brown dwarfs
• bulge: denser group of stars within a larger group
• Burnham Double Star Catalogue: 1906 catalog with multiple star systems and non-orbiting double stars
• calcium-rich gap transient: type of explosive event larger than a nova and smaller than a supernova
• California-Kepler Survey: follow-up to Kepler to determine stellar radii
• candidate companion: possible object apparently orbiting a known object
• Carlsberg Meridian Catalogue: series of astrometric catalogs from 19th century on
• Case-Hamburg Survey: 1950s-1970s survey(s) of OB stars
• Catalog of Azzopardi & Vigneau: probable stars in the SMC
• Catalog of Circumpolar Stars: list of over 4000 stars in northern part of the sky
• Catalog of Components of Double and Multiple Stars: 1994 catalog of 74000 such double-star components
• Catalog of Stellar Identification: a compilation of the catalogs, BD, CD, and CPD
• Catalog of Stellar Identifications: 1970s catalog cross referencing existing star catalogs
• Catalogue of Southern Double Stars: 1955 catalog with multiple star systems and non-orbiting double stars
• Catalogues of Fundamental Stars: series of astrometric catalogs from 19th century on
• CFHTLS: surveys of transients and stars
• Chandrasekhar limit: maximum mass of a white dwarf
• chromosphere: middle layer of the Sun's atmosphere
• chromospheric activity index: measure of magnetic activity of a star's chromosphere
• circumstellar disk: disk or ring shaped accumulation of matter around a star
• circumstellar envelope: shell-like cloud surrounding a star
• cold mass accretion: stellar accretion through an accretion disk
• color-color diagram: means of comparing characteristics of stars
• color-magnitude diagram: graph plotting color index to magnitude
• color-period diagram: means of comparing periods of stars at various wavelengths
• convection zone: region of a star transmitting energy through convection
• core collapse supernova: supernova resulting from the collapse of the core of a star
• corona: plasma surrounding a star
• coronal hole: cool, low-density portions of the Sun's corona
• coronal mass ejection: mass of plasma ejected from the Sun
• COROT: observatory-satellite to look for transiting exoplanets and stellar oscillations
• CTIO Upper-Scorpius OB Association Survey: survey of low-mass stars and brown dwarfs
• Dartmouth Stellar Evolution Database: database relating isochrones to stellar parameters
• debris disk: circumstellar disk of dust and debris around a star
• Deep Multicolor Survey: 1990s optical and infrared deep survey
• delay time distribution: characterization of interval from star formation until some type of event
• dredge-up: stellar convection bringing up fused material
• Dunlop Double Star Catalogue: 1829 catalog of double stars viewed from Australia
• dwarf nova: flash of a cataclysmic variable star
• Dynamical Analysis of Nearby Clusters: survey of stars in stellar clusters
• Eddington approximation: approximation of a star's internal EMR's divergence from isotropic
• Eddington luminosity: maximum luminosity at which radiation force overcomes gravity
• ejection: forcing or throwing something out
• electron capture supernova: supernova from collapse of iron-free stellar cores
• evolutionary track: H-R diagram track of the life of a star
• field: adjective meaning "in this field of view but unrelated"
• Flamsteed designation: star designation system dating from 1700s
• flux-weighted gravity-luminosity relationship: method of determining luminosity of distant stars
• Frank Ross's Catalog: high-proper-motion and variable stars catalogued by Frank Ross
• fusor: 2003 proposed term for astronomical objects capable of carrying out fusion
• G-dwarf problem: lack of metal-poor G dwarfs in the Milky Way
• Gaia: astrometry survey satellite launched in 2013
• gaia-kepler.fun: website with Gaia data on Kepler target stars
• GaiaHub: software to extract proper motions form Gaia and HST data
• galactic disk: the "disk" portion of a disk galaxy
• Galactic O Star Catalog: 2000s catalog of O-type stars
• galaxy main sequence: relation between galaxies' star formation and stellar mass
• General Catalogue of Stellar Radial Velocities: 1950s century catalog of 15000 stars with their radial velocities
• General Catalogue of Trigonometric Parallaxes: 1950s catalog of stars with parallax measures
• General Catalogue of Variable Stars: 20th/21st century catalog of 58000 variable stars
• Gliese Catalogue of Nearby Stars: 1950s catalog of stars within 20 parsecs
• Gliese-Jahreiss Catalog: 1991 catalog of stars within 25 parsecs
• globular cluster: spherical group of stars orbiting a galaxy
• Gould's Belt: ring of stars around the sky
• GRB-supernova: supernova that produces a GRB
• Groupe Europáen Observations Stellaires: European organization of variable star observers.
• Guide Star Catalog: catalog of stars to help aim HST
• GYRE: a stellar oscillation code
• gyrochronology: means of estimating stellar age from rotation
• H-R diagram: diagram relating effective temperature to luminosity
• H3 Survey: spectroscopic survey of Milky Way halo stars
• H₂O Southern Galactic Plane Survey: survey targeting water masers
• Hamburg/ESO Survey: 1990s southern hemisphere survey aimed at finding quasars
• Hayashi limit: limit on the temperature of a star dependent upon its mass and luminosity
• Hayashi track: H-R diagram track of evolution of some pre-main-sequence stars
• Heggie-Hills law: hard binary stars generally get harder when encountering a third star
• helium flash: helium ignition in a star
• helium runaway: helium fusion positive feedback through its generated heat
• Henry Draper Catalog: early 20th century spectroscopic catalog of stars
• Henyey track: H-R diagram track of stellar evolution after the Hayashi track
• Herschel Double Star Catalog: series of early double star catalogs
• Herz catalog: list of 3000 stars in a strip of the southern sky
• Hess diagram: diagram relating effective temperature to luminosity
• HK Survey: 1985 search for metal poor-stars using calcium lines
• host star: the star associated with a planetary system
• hypercompact stellar system: SMBH with no galaxy but has a tight stellar cluster
• Information Bulletin on Variable Stars: former 1961-2019 publication on variable stars
• initial mass function: function describing initial mass of stars
• instability strip: region of H-R diagram where stars are unstable
• International Variable Star Index: variable star catalog by AAVSO
• interstellar magnetic field: galactic magnetic field between that of stars
• isochronal fitting: method of estimating stellar age from retrievable parameters
• isochrone: line of equal ages on an HRD
• isothermal core: core region of a body of all the same temperature
• Japan Amateur Photoelectric Observers Association: past amateur astronomy collaboration
• kappa mechanism: stellar instability caused by opacity increasing with temperature
• Kepler-Swift Active Galaxies and Stars Survey: X-ray/UV survey of objects within the Kepler field
• kilonova: transient associated with merging neutron stars
• Lépine Shara Proper Motion catalog: 2000s catalog of stars with proper motion
• Lacaille Star Catalog: 1700s catalog of about 10,000 southern hemisphere stars
• LaSilla-QUEST Variability Survey: survey for transients
• Lick indices: defined set of spectral line indexes for stars
• Local Group Galaxy Survey: photometric survey of stars in a number of local group galaxies
• Lowell Proper Motion Survey: 1950s-1970s catalogs of stars with proper motion
• luminosity class: classification of size/luminosity of stars
• luminosity function: function giving number of stars or galaxies at different luminosities
• luminous red nova: red-colored event theorized to be a merger of two stars
• Luyten Double Star Survey: 1940s-1970s catalog of double stars
• Luyten Half-second Catalog: 1979 catalog of 4000 stars with high proper motion
• Luyten Palomar Survey: 1970s catalog of stars with high proper motion
• Luyten Two-Tenths Arcsecond Catalog: 1960 catalog of 9000+ stars with proper motion
• Magellanic Catalogue of Stars: 1980s/1990s survey of stars in Magellanic Clouds
• magnetorotational supernova: type of core collapse supernova
• main-sequence lifetime: length of time that a star remains within the main sequence
• MaNGA Stellar Library: catalog of SEDs of representative stars
• mass fraction: measure of a constituent of a star, cloud, etc.
• mass loss: a star's reduction in mass
• mass-luminosity relation: model relating stellar mass and luminosity
• mass-radius relation: model relating stellar mass and radius
• mass-to-light ratio: measure of a population of stars or region
• MATCH: SFH code
• Max Wolf's catalog of stars with proper motion: early 20th century catalog of 1500 stars
• mean molecular weight: measurement of a gas usual for approximating in gas models
• MESA: collection of stellar astrophysics code
• microquasar: stellar-sized black hole with quasar-like activity
• Milky Way Mapper: SDSS spectrographic survey of Milky Way stars
• MISAO project: search for variable stars and transients
• moving group: observed group of stars with similar motion
• moving-cluster method: method of measuring distance to a nearby star cluster
• multiplicity fraction: fraction of star systems that are multiple-star systems
• MUSCLES: HST UV survey of some M Dwarfs that host exoplanets
• N30 Catalog: 1950s catalog collecting proper motion data from older catalogs
• near-Earth supernova: supernova near enough to Earth to affect it
• New Catalogue of Suspected Variable Stars: catalog from latter half of 20th century catalog
• NOMAD: astrometric star catalog
• north polar sequence: set of stars previously used to define magnitudes
• nova: white dwarf explosion
• OB association: stellar association including O and/or early B class stars
• Oort constants: two constants characterizing local Milky-Way motion
• open cluster: group of stars within a galaxy apparently formed by a single cloud
• pair-instability supernova: type of large supernova
• Palomar-Haro-Luyten Catalog: 1960s catalog of faint blue stars
• Panoramic Imaging Survey of Centaurus and Sculptor: survey of extended halos of two nearby galaxies
• Parker wind: model of the solar wind
• partial ionization zone: portion of some stars where gas is partially ionized
• PHOENIX stellar model: computer model of a stellar photosphere
• photosphere: layer of star from which light propagates
• Pico dos Dias Survey: survey aimed to find T-Tauri stars
• plane-parallel atmosphere: simplified atmosphere model ignoring its curvature around the body
• planetary nebula: glowing gas shell ejected by a red giant
• planetary system: all the planets orbiting a star
• PPM Star Catalogue: 1991 astrometric catalog with proper motions
• protoplanetary nebula: short AGB phase before planetary nebula
• protostar: contracted mass of gas that will become a star
• pseudobulge: like a galaxy bulge only flatter
• quadratic field strength: a measure of a star's varying magnetic field
• quasar: distant, bright object that appears something like a star
• Radcliffe Observatory Magellanic Clouds Catalogue: catalog of stars in
• radiation zone: region of a star transmitting energy through radiative diffusion
• radio supernova: supernova that includes a detectable radio emission
• RECONS: consortium for research on stars near the Sun
• reddening: red appearance of astronomical objects because blue light is attenuated by dust
• Rosseland mean opacity: a useful weighted average of opacities at all the frequencies
• SAO Star Catalog: 1960s catalog
• Schönberg-Chandrasekhar limit: maximum stellar isothermal helium core mass
• Schuster-Schwarzschild model: simplified model of a star's production of absorption lines
• seismic waves: waves broadcast through Earth from earthquakes
• SIMP: 2000s infrared proper-motion survey
• snow line: distance from protostar so cool that water condenses
• solar neighborhood: Milky Way in the vicinity of the Sun
• Southern Stellar Stream Spectroscopic Survey: spectroscopic survey of seven southern-hemisphere stellar streams
• spectral class: overall classification of stars based upon spectral features
• spectral type: classification of stars based upon spectral features
• spectroscopic parallax: stellar distance determined through spectroscopy
• Spectroscopic Properties of Cool Stars: analysis of spectroscopic data of 7000+ M and L stars
• SPLASH: survey of M31's Giant Stellar Stream
• SSP: set of stars born at the same time with the same metallicity
• star cloud: lighter region of the night sky consisting of a high density of stars
• star count: surveys of stars counting them according to some criteria
• star formation: theorized collapse of gas and dust into stars
• star system: a gravitationally bound set of a few stars
• STARBURST99: software to simulate star-forming galaxies
• STarSPot: code to model starspots
• stellar activity: transient behavior of a star
• stellar age determination: methods of estimating a star's age
• stellar association: like a large open cluster but even less tightly bound
• stellar astronomy: astronomy of the birth, structure, variety, evolution, and fate of stars
• stellar atmosphere: photosphere and above
• stellar birth rate function: function describing the birth rate of stars by mass
• stellar cluster: group of stars apparently formed by a single cloud
• stellar core: the middle of a star
• stellar demographics: statistics regarding the number of stars
• stellar designation: identifiers for stars
• stellar distance determination: methods by which the distance to a star is determined
• stellar dynamics: stars' gravitational interaction
• stellar encounter: stars passing close to each other
• stellar evolution: the pattern of a star's changing structure over its life
• stellar flare: sudden brightening of a star
• stellar halo: the lesser number of nearby stars surrounding a galaxy
• stellar kinematics: science of the movement of stars
• stellar luminosity determination: methods by which the luminosity of a star is determined
• stellar mass determination: methods by which the mass of a star is determined
• stellar merger: two stars combining into one
• stellar model atmosphere: simulation of the star's production of emitted EMR
• stellar overdensity: portion of galactic halo with more stars than normal
• stellar parameter determination: methods by which the parameters of stars are determined
• stellar population synthesis: using spectral characteristics of galaxies to characterize their stellar populations
• stellar population synthesis code: software to perform stellar population synthesis
• stellar radius determination: methods by which the radius of a star is determined
• stellar rotation: rotation of a star around an axis through the middle
• stellar stream: long group of co-moving stars
• stellar structure: the presumed internal structure of stars
• stellar temperature determination: methods by which the temperature of a star is determined
• stellar wind: gas or plasma emanating from a star
• stellar-mass black hole: black hole that is a stellar remnant
• Struve Catalogs: two catalogs of double stars
• substellar point: point on a body such that a particular star is at the zenith
• sunspot: temporary darker region of the Sun's surface
• SuperCOSMOS Sky Survey: survey of stars and galaxies from legacy plates
• superluminous supernova: stellar explosion larger than a supernova
• supernova: stellar explosion larger than a nova
• supernova impostor: extreme stellar explosion that does not destroy the star
• surface abundance: quantity such as mass per surface area
• surface gravity: measure of gravity at the surface of a body
• surface temperature: temperature of the surface of a star or planet
• synthetic spectrum: simulated spectrum, e.g., of a type of star
• T association: stellar association with T-Tauri stars
• T4 Automated Photometric Telescope: automated 75-cm telescope to a long-term star monitoring survey
• Taurus-Auriga Complex: nearby star-forming region
• thermal pulse: pulse in an AGB star due to helium fusion in a shell
• thermal runaway: situation where heat triggers more heat production
• tidal capture: bodies entering orbit through dissipation of energy by tides
• Tolman-Oppenheimer-Volkoff limit: maximum mass of a neutron star
• traditional approximation of rotation: approximation of waves on a rotating body
• turn-off point: point in H-R diagram of a cluster where stars turn red
• Two Micron All-sky Survey: near-infrared survey of both hemispheres
• Two Micron Sky Survey: 1969 infrared catalog produced by Caltech
• two-stream approximation: approximation of a star's internal EMR's divergence from isotropic
• Type Ia supernova: type of supernova for which distance can be determined
• USNO CCD Astrograph Catalog: USNO star catalog including proper motions
• variable star designation: Bayer system variant for variable stars
• velocity kick: substantial acceleration from a supernova
• velocity-metallicity relation: higher stellar velocity correlates with lower metallicity
• VLT-FLAMES Tarantula Survey: VLT spectroscopic survey of massive stars
• Vogt-Russell theorem: proposition that a star's structure depends on its mass and makeup
• Washington Double Star Catalog: modern database of double stars
• Whole Earth Telescope: international initiative to gather variable star lightcurves
• Wilson-Bappu effect: a relation between a star's spectral line and luminosity
• wind-momentum luminosity relationship: method of determining luminosity of distant stars
• WINGS: all-sky survey investigating known galaxy clusters
• Working Group for Planetary System Nomenclature: IAU group on terminology regarding planetary systems
• XZ Catalog of Zodiacal Stars: 1977 catalog of stars near the ecliptic
• Yale Observatory Zone Catalog: mid-20th century catalogs totaling 400,000 stars
• Zanstra method: method of determining temperature of a hot star within a nebula
• zero-age main sequence: describes stars that just began hydrogen fusion
• [α/Fe] versus [Fe/H] diagram: diagram indicating stars' degree of alpha enhancement
• StarScan machine: see plate measuring machine
• starshade: spacecraft to block light from a specific body
• Starship
• Space Launch System: launch rocket in development, e.g., for future astronomical projects
• Starshot: plan for mission to fly by Alpha Centauri
• STARSMOG: survey of dust in galaxies
• STarSPot: code to model starspots
• starspot: see sunspot
  • variable star: star that varies in magnitude
• StarTrack: stellar population synthesis code
• state of excitation: energy level of something above the minimum
• state of ionization: difference in an ion's electron count versus proton count
  • ionizing radiation: radiation with photon energy sufficient to ionize
• state of matter
• supercritical fluid: state of matter at sufficient pressure and temperature
• STATIC: see MAVEN
• static limit: see black hole
• static surface: see black hole
• statics: see mechanics
  • celestial mechanics: study of forces and motion of celestial objects
  • hydrostatic equilibrium: state of a fluid body when forces are such that the fluid is at rest
• station keeping (stationkeeping): spacecraft operation to keep it in its orbit
• stationkeeping: spacecraft operation to keep it in its orbit
• statistical dispersion: see velocity dispersion
• statistical equilibrium: see local thermodynamic equilibrium
• statistical isotropy (isotropy): uniformity in all directions
• statistical mechanics: mechanical behavior based upon probability
  • effective field theory: type of useful simplification of a field theory
  • Fokker-Planck equation: shows likelihood of velocity over time of a disturbed particle
  • mechanics: the science of forces and motions
  • partition function: scale factor for Boltzmann factors
  • phase space: space of all possible states of a system
• statistical physics (statistical mechanics): mechanical behavior based upon probability
  • random walk: movement with random turns
• statistical regression
• symbolic regression: automated model-building by tinkering with formulae
• statistical weight (degeneracy weight): number of quantum states with same energy level
• statistics
• Akaike information criterion: particular formula for comparison of statistical models
• Approximate Bayesian Computation: shortcut-method in Bayesian statistics
• balanced accuracy: average of true positive and negative rates
• Bayesian statistics: statistics method assigning probability to your belief
• Bose-Einstein statistics: possible distribution of particles not bound by Pauli exclusion
• chi-squared test: statistical significance test
• demographics: statistics of characteristics within a group
• dynesty: code for comparing the applicability of multiple models
• Eddington bias: selection bias from mistaking something common for something rare
• error bar: feature of a graph to indicate accuracy
• Fisher information: measure of the information provided by experimental data
• Gaussian function: function producing the bell curve
• Gini/M20: an automatable method of detecting whether a galaxy has recently merged
• kurtosis: measure of the probability of a distribution's tails
• Lutz-Kelker bias: measurement bias due to unbalanced parallax uncertainties
• Malmquist bias: selection bias from detecting only the brighter objects
• maximum likelihood estimation: statistical method to find likely parameters
• maximum likelihood mapmaking: method of making maps using varying data
• mixture: type of probability distribution resulting from two others
• mixture density network: machine learning technique
• mlmapper: software for maximum-likelihood mapmaking
• N-point function: general term for analyses-techniques of spatial data
• nonparametric model: model developed avoiding assumptions regarding a basic structure
• normal distribution: familiar probability distribution with bell curve shape
• parts per million: method of expressing a small ratio
• PCA analysis: an automatable method of determining galaxy morphology
• Period04: software to identify periods in time series data
• planet demographics: statistics regarding the number of planets
• Poisson distribution: statistics on count of events happening within a given interval
• power law: relationship between a quantity and a power of another
• principal component analysis: statistical strategy of devising independent variables
• probability density function: shows probability of taking a particular value from a continuous range
• probability mass function: shows probability of taking one of a number of discrete values
• PyMC: Python package for Bayesian statistical modeling
• RMS: square root of the average of the squares of some values
• Scott effect: bias toward finding clusters that have bright galaxies
• selection bias: selection of a sample set that is not appropriately randomized
• sigma: indication of the confidence level of an experiment
• spectral density: strength of power or energy as a function of frequency
• stellar demographics: statistics regarding the number of stars
• velocity dispersion: statistical dispersion of velocities of a group of objects
• volume weighting: method of accommodating the Malmquist bias
• Zipf's law: particular discrete probability distribution discovered in linguistics
• stau: see supersymmetry
• steady state model: see alternative cosmologies
• steady-state universe: see Big Bang
• STEAM: see PUNCH
• steam atmosphere: see water vapor planet
• steam phase: see atmosphere formation
• steam planet (water vapor planet): planet showing water vapor in its atmosphere
• Stefan's constant (Stefan-Boltzmann constant): relates radiation power to temperature and surface area
• Stefan-Boltzmann constant: relates radiation power to temperature and surface area
• Stefan-Boltzmann equation: see Stefan-Boltzmann constant
• Stefan-Boltzmann law: see Stefan-Boltzmann constant
• Stein: see double star designation
• STELLA: two robotic telescopes in Canary Islands
  • Roque de los Muchachos Observatory: observatory at La Palma in the Canary Islands
• Stellar Activity (STELLA): two robotic telescopes in Canary Islands
• stellar activity: transient behavior of a star
• stellar age
• stellar parameter determination: methods by which the parameters of stars are determined
• stellar age determination: methods of estimating a star's age
• stellar association: like a large open cluster but even less tightly bound
  • Scorpius-Centaurus Association: nearby OB association
  • Tucana Horologium association: nearby stellar association
  • TW Hydrae association: nearby stellar association
• stellar astronomy: astronomy of the birth, structure, variety, evolution, and fate of stars
• stellar atmosphere: photosphere and above
  • atmosphere: gas surrounding astronomical object
  • chromosphere: middle layer of the Sun's atmosphere
  • corona: plasma surrounding a star
  • photosphere: layer of star from which light propagates
  • transition region: middle layer of the Sun's atmosphere
• stellar BH (stellar-mass black hole): black hole that is a stellar remnant
• stellar birth rate function: function describing the birth rate of stars by mass
• stellar black hole (stellar-mass black hole): black hole that is a stellar remnant
  • black hole: region of such high mass that light cannot escape
  • collapsar: neutron star or stellar black hole
  • stellar evolution: the pattern of a star's changing structure over its life
• stellar cluster: group of stars apparently formed by a single cloud
  • alpha-enhanced: metallicity with a high percentage of alpha elements
  • field star: star that is not part of a star cluster
  • stellar dynamics: stars' gravitational interaction
• stellar collision (stellar merger): two stars combining into one
• stellar core: the middle of a star
• stellar demographics: statistics regarding the number of stars
• stellar designation: identifiers for stars
• stellar distance
• stellar parameter determination: methods by which the parameters of stars are determined
• stellar distance determination: methods by which the distance to a star is determined
• stellar dynamics: stars' gravitational interaction
  • stellar kinematics: science of the movement of stars
• stellar encounter: stars passing close to each other
• stellar envelope (stellar atmosphere): photosphere and above
• stellar evolution: the pattern of a star's changing structure over its life
  • asymptotic giant branch: a second stage of helium burning in some stars
  • BaSTI: database relating isochrones to stellar parameters
  • blue horizontal branch: blue end of the horizontal branch
  • BSE: a code to model the evolution of a binary star system
  • collapsar: neutron star or stellar black hole
  • common envelope: binary star system surrounded by a single gas cloud
  • compact object: dense astronomical body such as white dwarf or denser
  • Dartmouth Stellar Evolution Database: database relating isochrones to stellar parameters
  • dredge-up: stellar convection bringing up fused material
  • evolutionary track: H-R diagram track of the life of a star
  • FU Orionis star: type of variable pre-main-sequence star
  • giant star: star larger than main sequence stars
  • Hayashi track: H-R diagram track of evolution of some pre-main-sequence stars
  • helium flash: helium ignition in a star
  • helium runaway: helium fusion positive feedback through its generated heat
  • Henyey track: H-R diagram track of stellar evolution after the Hayashi track
  • Herbig AeBe star: type of pre-main-sequence star more massive than a T-Tauri star
  • horizontal branch: a second "giant" stage in the evolution of some main sequence stars
  • hypergiant: extremely bright stars
  • isochrone: line of equal ages on an HRD
  • main sequence star: star burning hydrogen into helium in its center
  • neutron star: stellar remnant consisting entirely of solar masses of neutrons
  • planetary nebula: glowing gas shell ejected by a red giant
  • post-common-envelope binary: binary star system showing unusual stellar evolution
  • post-main-sequence star: star evolved beyond its main sequence phase
  • pre-main-sequence star: star not yet with a nuclear reaction
  • protostar: contracted mass of gas that will become a star
  • red clump: like horizontal branch but at one temperature
  • red giant: very bright red star
  • red-giant branch: the first red-giant phase of post-main-sequence stellar evolution
  • stellar remnant: leftovers from a mainstream star
  • subdwarf: star less bright than the main sequence given its spectral class
  • subgiant: slightly larger than normal star
  • supergiant: very large giant star
  • T-Tauri star: type of variable pre-main-sequence star
  • thermal pulse: pulse in an AGB star due to helium fusion in a shell
  • thermal runaway: situation where heat triggers more heat production
  • TYCHO: stellar evolution code
  • Vogt-Russell theorem: proposition that a star's structure depends on its mass and makeup
  • young stellar object: early stage of a star
• stellar evolution model: see stellar evolution
• stellar feedback (star formation feedback): mechanisms whereby star formation regulates its own rate
• stellar flare: sudden brightening of a star
  • solar eruption: sudden brightening of the Sun
  • solar flare: sudden brightening of the Sun
• stellar flyby: see flyby
• stellar halo: the lesser number of nearby stars surrounding a galaxy
  • galactic halo: spherical region around a galaxy with gas, dark matter, etc.
• stellar intensity interferometer (intensity interferometer): interferometer based upon interference from intensity variations
  • Hanbury Brown and Twiss effect: EMR interference stemming from variation in intensity
• stellar intensity interferometry: see intensity interferometer
• stellar isochrone: see isochrone
• stellar jet: see jet
• stellar kinematics: science of the movement of stars
  • high-velocity star: star moving noticeably faster than neighbors
  • hypervelocity star: star moving very much faster than usual
• stellar lifetime (main-sequence lifetime): length of time that a star remains within the main sequence
• stellar luminosity
• mass-luminosity relation: model relating stellar mass and luminosity
• stellar parameter determination: methods by which the parameters of stars are determined
• stellar luminosity class (luminosity class): classification of size/luminosity of stars
• stellar luminosity determination: methods by which the luminosity of a star is determined
• stellar magnetic field: see magnetic field
• stellar mass
• galaxy main sequence: relation between galaxies' star formation and stellar mass
• mass function: measure of binaries that constrains the masses
• mass-luminosity relation: model relating stellar mass and luminosity
• stellar mass determination: methods by which the mass of a star is determined
• stellar parameter determination: methods by which the parameters of stars are determined
• stellar mass determination: methods by which the mass of a star is determined
• stellar mass loss (mass loss): a star's reduction in mass
• stellar merger: two stars combining into one
• stellar metallicity
• stellar parameter determination: methods by which the parameters of stars are determined
• stellar model (stellar structure): the presumed internal structure of stars
• stellar model atmosphere: simulation of the star's production of emitted EMR
• stellar nucleosynthesis: see nucleosynthesis
• stellar nucleus: group of many stars at the center of a galaxy
• stellar nursery (star-forming region): area forming stars and/or ready for star formation
• stellar occurrence rate (stellar demographics): statistics regarding the number of stars
• stellar oscillation
• GYRE: a stellar oscillation code
• stellar overdensity: portion of galactic halo with more stars than normal
• stellar parallax: see parallax
• stellar parameter determination: methods by which the parameters of stars are determined
• Stellar Planet Survey: astrometric search for planets around nearby stars
• stellar population: grouping of stars according to metallicity
• stellar population synthesis: using spectral characteristics of galaxies to characterize their stellar populations
  • A-LIST: catalog of templates of H-band spectra for SPS
  • BPASS: evolution and population synthesis code for binary stars
  • COMPAS: SPS code for compact object binaries
  • FSPS: code library for stellar population synthesis
  • StarTrack: stellar population synthesis code
  • stellar population synthesis code: software to perform stellar population synthesis
• stellar population synthesis code: software to perform stellar population synthesis
• stellar population synthesis model: see stellar population synthesis
• stellar pulsation: see pulsating star
• stellar radio source (radio star): star emitting much radio
• stellar radius
• stellar parameter determination: methods by which the parameters of stars are determined
• stellar radius determination: methods by which the radius of a star is determined
• stellar remnant: leftovers from a mainstream star
  • collapsar: neutron star or stellar black hole
  • stellar-mass black hole: black hole that is a stellar remnant
• stellar remnant BH (stellar-mass black hole): black hole that is a stellar remnant
• stellar remnant black hole (stellar-mass black hole): black hole that is a stellar remnant
• stellar rotation: rotation of a star around an axis through the middle
  • stellar parameter determination: methods by which the parameters of stars are determined
• stellar seismology (asteroseismology): study of stars through analysis of their pulsation
• stellar spot: see sunspot
• stellar stream: long group of co-moving stars
  • galaxy interaction: the effects of galaxies being near each other
  • GD-1: stellar stream formed by globular cluster
  • Giant Stellar Stream: extensive stellar stream in M31
  • Monoceros Ring: stellar stream wrapping around the Milky Way
  • Orphan stream: stellar stream wrapping around the Milky Way
  • Southern Stellar Stream Spectroscopic Survey: spectroscopic survey of seven southern-hemisphere stellar streams
  • stellar overdensity: portion of galactic halo with more stars than normal
  • Virgo Stellar Stream: stellar stream wrapping around the Milky Way
• stellar streams
• Field of Streams: region of sky crossed by a number of stellar streams
• stellar halo: the lesser number of nearby stars surrounding a galaxy
• stellar structure: the presumed internal structure of stars
  • BPASS: evolution and population synthesis code for binary stars
  • convection zone: region of a star transmitting energy through convection
  • gray atmosphere: a model atmosphere whose opacity does not depend upon wavelength
  • kappa mechanism: stellar instability caused by opacity increasing with temperature
  • mass shell: conceptual volume of mass shaped like a hollow sphere
  • mixing length theory: tractable simplified model of convection
  • nuclear energy generation rate: fusion power per unit mass
  • partial ionization zone: portion of some stars where gas is partially ionized
  • radiation zone: region of a star transmitting energy through radiative diffusion
  • stellar core: the middle of a star
  • Vogt-Russell theorem: proposition that a star's structure depends on its mass and makeup
• stellar structure model (stellar structure): the presumed internal structure of stars
• stellar system: see solar system
• stellar system: see star system
• stellar temperature
• stellar parameter determination: methods by which the parameters of stars are determined
• stellar temperature determination: methods by which the temperature of a star is determined
• stellar velocity: see stellar kinematics
• stellar wind: gas or plasma emanating from a star
  • CMFGEN: RT code designed to handle significant stellar wind
  • Parker wind: model of the solar wind
• stellar-cluster collapse
• SMBH formation: process by which SMBHs form
• stellar-mass BH (stellar-mass black hole): black hole that is a stellar remnant
• stellar-mass black hole: black hole that is a stellar remnant
  • black hole: region of such high mass that light cannot escape
  • black hole merger: two black holes meeting and forming one
• stellar-mass star-formation rate ratio (star-formation rate stellar-mass ratio): ratio between a galaxy's stellar mass and its SF rate
• stellar-structure equations: see stellar structure
• stellar-wind bubble: see stellar wind
• Stelle Doppie: online database of double stars
• stencil: pattern of input to numerical solutions at a point
• Steph: see rare designator prefixes
• Stephan's Quintet: five galaxies grouped in the sky
• STEPS (Stellar Planet Survey): astrometric search for planets around nearby stars
• steradian: see solid angle
• STEREO: two-satellite system to observe the Sun
• STEREO-1: see STEREO
• STEREO-2: see STEREO
• sterile neutrino: see neutrino
• Sternberg Astronomical Institute
• ITEP-SAI Supernova Light Curve Catalogue: online catalog
• Sterncatalog für die Zone von 6° bis 10° südlicher Declination für das Aequinoctium 1890 (Herz catalog): list of 3000 stars in a strip of the southern sky
• Steward observatory
• Kitt Peak National Observatory: NOIRLab observatory in Arizona with Mayall telescope
• Steward Observatory 0.9-meter Spacewatch telescope: see SPACEWATCH
• Steward Observatory Asteroid Relational Database: 1980s/1990s repository of asteroid data
• STF: see Struve Catalogs
• STFC (Science and Technology Facilities Council, UK): UK research agency
  • Astronet: European astronomy consortium
• STH: see double star designation
• StHA: see rare designator prefixes
• stiff EoS: see equation of state
• stimulated emission: emission triggered by received photons
• stimulated emission: see emission
  • Einstein coefficients: a substance's probabilities of emission and absorption
  • maser: electromagnetic radiation amplified by stimulated emission
• STIS: see Hubble Space Telescope
• STIS: see SWFO-L1
• STIS: see rare designator prefixes
  • imaging spectrometer: device to capture spectrum point-by-point of an image
• STIX: see Solar Orbiter
• STJ (superconducting tunnel junction): type of Josephson junction usable in EMR sensors
• Stk (Stokes number): measure of a particle's tendency to follow the flow of a fluid
• StKM: see rare designator prefixes
• STN: see double star designation
• STO: see GUSTO
• STO2: see GUSTO
• stochastic background (gravitational wave background): combination of weak gravitational waves such as from distant sources
• Stock: see rare designator prefixes
• Stokes map: see Stokes parameters
• Stokes number: measure of a particle's tendency to follow the flow of a fluid
• Stokes parameters: means of describing a polarization state
• Stokes shift: see fluorescence
• stop: see Lyot stop
• STPSat 6: see UVSC Pathfinder
• STR: see rare designator prefixes
• Str: see Duus-Newell catalog
• Strömgren photometric system: four-color photometric system devised in 1950s
• Strömgren sphere: sphere of ionized hydrogen around an OB star
• strain (gravitational wave strain): a measure of the magnitude of a gravitational wave
• Strand: see rare designator prefixes
• strange: see flavor
• strange matter: see quark matter
• strange quark: see particle
• strange quark: see quark
  • exotic star: term for theoretical stars not made of atoms/ions
  • hyperon: exotic type of baryon
  • quark matter: matter not made of protons and neutrons but of quarks
  • standard model: model of elementary particles including quarks
• strange quark matter: see quark matter
  • exotic star: term for theoretical stars not made of atoms/ions
  • neutron star: stellar remnant consisting entirely of solar masses of neutrons
• strange star: see exotic star
• strange star: see quark matter
• Strasbourg Astrophysical Data Center (Centre de données astronomiques de Strasbourg): repository of astronomical data
• Strasbourg-ESO Catalog of Galactic Planetary Nebulae: 1992 catalog of 1820 objects
• stratigraphy: study of rock layering
• stratopause: see atmospheric temperature profile
• stratosphere: see atmospheric temperature profile
• Stratospheric Observatory for Infrared Astronomy (SOFIA): aircraft-based infrared observatory
• Stratospheric UV Demonstrator of an Imaging Observatory (STUDIO): balloon-borne 0.5 m ultraviolet telescope
• stray light: unintended light reaching a telescope's sensors
• stray light mitigation: see stray light
• StrayCats: survey of X-ray sources detectable in NuSTAR stray light
• streaming instability: type of interplay between disk gas and solids that brings solids together
  • radial drift: inward drift of objects within a protoplanetary disk
• Strehl ratio: measure of optical aberration
  • wavefront error: measure of a class of telescope distortion
• strewn field: region with fragments of a meteor impact
• strewn-field (strewn field): region with fragments of a meteor impact
• strewnfield (strewn field): region with fragments of a meteor impact
• striae: parallel ridges
• string: see string theory
• string theory: type of physics theory bringing together current models
  • cosmic string: rent in spacetime
  • entropic gravity: MOND-like theory of gravity
  • graviton: quantum of gravity
  • Theory of Everything: single law explaining the four forces of nature
• Stripe 82: SDSS field in southern hemisphere
• stripped SN: see core collapse supernova
• stripped star: star with substantial material removed by a binary companion
• stripped supernova: see core collapse supernova
• stripped-envelope star (stripped star): star with substantial material removed by a binary companion
• stripped-envelope supernova: see core collapse supernova
• STROBE-X: space X-ray telescope plan
• Stromlo: see rare designator prefixes
• strong cosmic censorship: see law of cosmic censorship
• strong CP problem
• axion: proposed light, electrically neutral elementary particle
• strong encounter: see stellar dynamics
• strong encounter: see stellar encounter
• strong force: force that holds quarks and nuclei together
  • electroweak: single conception including both electromagnetic and weak forces
  • particle: very small thing
  • physical field: physical property of some volume of space
  • quark: type of elementary particle incorporated in protons and neutrons
  • Theory of Everything: single law explaining the four forces of nature
  • topological defect: defect in space that could arise in the early universe
• strong gravitational encounter: see stellar dynamics
• strong gravitational interaction
• globular cluster: spherical group of stars orbiting a galaxy
• strong gravitational lens: see gravitational lensing
• strong gravitational lensing: see weak lensing
• strong interaction (strong force): force that holds quarks and nuclei together
• strong interaction: see N-body problem
• strong lensing: see weak lensing
• strong r-process: see r-process
• Strong Radio Source Surveys (Strong Source Surveys): series of 1970s/1980s 5 GHz surveys
• Strong Source Surveys: series of 1970s/1980s 5 GHz surveys
• strong stellar encounter: see stellar encounter
• strong-field gravity: gravity much stronger than in the solar system such as near a black hole
• strong-field gravity physics
• strong-field gravity: gravity much stronger than in the solar system such as near a black hole
• strongly-coupled QFT: see quantum field theory
• strongly-coupled quantum field theory: see quantum field theory
• strontium
• Am star: A-type star with metallic lines
• Ap star: peculiar type of A star
• StRS: see rare designator prefixes
• structure (stellar structure): the presumed internal structure of stars
• structure formation: formation of dark matter halos, galaxy clusters, and galaxies
• structure of the universe (large scale structure): the universe's structure as in placement of clusters
• Struve: see Struve Catalogs
• Struve 1341 B b (HD 80606 b): hot Jupiter discovered in 2001
• Struve Catalogs: two catalogs of double stars
• STS (Space Transport System): early NASA plan for a Space-Shuttle-like vehicle
• STScI (Space Telescope Science Institute): science operator of space telescopes
  • MAST: archive of data from surveys and missions
• STSDAS (Space Telescope Science Data Analysis System): software designed for analysis of HST data
• STSI (Space Telescope Science Institute): science operator of space telescopes
  • MAST: archive of data from surveys and missions
• STSP (STarSPot): code to model starspots
• STT: see Struve Catalogs
• STTA: see Struve Catalogs
• Students for the Exploration and Development of Space: student-run organization focused on space exploration
• STUDIO: balloon-borne 0.5 m ultraviolet telescope
• StWr: see rare designator prefixes
• Styx: see Pluto
• sub-brown dwarf: see planetary mass object
  • free-floating planet: planet that is not orbiting a star
  • WISE 0855-0714: nearby brown dwarf
• sub-Chandrasekhar mass: see supernova progenitor
• sub-GeV dark matter: a more-massive type of CDM
• sub-halo abundance mapping (SHAM): method of galaxy mock-catalog creation
• sub-halo mass function: see halo mass function
• sub-Neptune (mini-Neptune): planet with characteristics a bit like Earth but more like Neptune
• sub-Neptune: see super-Earth
• sub-threshold gravitational wave: see GW detection
• sub-threshold GW: see GW detection
• Subaru (Subaru Telescope): 8.2-meter telescope in Hawaii
  • Subaru Deep Field: survey of a small region of the sky using the Subaru telescope
  • Subaru XMM-Newton Deep Survey: survey using the Subaru telescope and XMM-Newton
• Subaru Deep Field: survey of a small region of the sky using the Subaru telescope
• Subaru PFS: multi-object spectrograph in development for the Subaru telescope
  • Wide-field Multi-object Spectrograph: proposed instrument to detect baryon acoustic oscillations
• Subaru Prime Focus Spectrograph (Subaru PFS): multi-object spectrograph in development for the Subaru telescope
• Subaru Strategic Program: see Subaru PFS
• Subaru Telescope: 8.2-meter telescope in Hawaii
  • Mauna Kea: Hawaiian mountain, the site of observatories
  • Mauna Kea Observatories: observatories on Mauna Kea in Hawaii
  • PALMS: survey to find exoplanets for direct imaging
• Subaru XMM Deep Survey (Subaru XMM-Newton Deep Survey): survey using the Subaru telescope and XMM-Newton
• Subaru XMM-Newton Deep Field: see Subaru XMM-Newton Deep Survey
• Subaru XMM-Newton Deep Survey: survey using the Subaru telescope and XMM-Newton
• subduction zone
• Europa: well-known Jupiter moon
• subdwarf: star less bright than the main sequence given its spectral class
  • luminosity class: classification of size/luminosity of stars
• subgiant: slightly larger than normal star
  • giant star: star larger than main sequence stars
• subgiant branch: see subgiant
• subgrid physics (subgrid-scale physics): shortcuts handling physics on a smaller scale than a simulation's grid
• subgrid-scale physics: shortcuts handling physics on a smaller scale than a simulation's grid
• subgroup (galaxy subgroup): a major galaxy and its satellites
• subgroup: see galaxy group
  • Milky Way subgroup: the Milky Way and its satellites
• subhalo: see dark matter halo
• sublimation: single material phase transition from solid to gas
• submillimeter
• Africa Millimetre Telescope: planned 15 m radio telescope array in Namibia
• Archeops: balloon-borne 1.3 m submillimeter telescope
• ASTHROS: balloon-borne 2.5-m submillimeter telescope
• Atacama Large Millimeter Array: advanced millimeter-telescope array in Chile
• Atacama Pathfinder Experiment: 12-meter submillimeter telescope in Chile
• beat frequency: frequency emerging from two other frequencies
• BLAST: balloon-borne 1.8-m submillimeter telescope
• bolometer: instrument measuring heat produced by radiation
• Caltech Submillimeter Observatory: 10.4 meter submillimeter telescope previously in Hawaii
• CCAT: 25-meter submillimeter telescope plan for Chile
• DESHIMA: submillimeter spectrometer
• EXCLAIM: planned balloon-borne 70-cm telescope with spectrometers
• far infrared: infrared radiation with wavelengths in the 30-450 μm range
• Fred Young Submillimeter Telescope: 6-meter submillimeter survey telescope under construction in Chile
• Herschel Space Observatory: infrared observatory-satellite with 3.5-meter reflector
• infrared: light with wavelength too long for our eyes to sense
• IRSA: archive center for infrared data from NASA missions
• LABOCA Extended Chandra Deep Field-South Submillimetre Survey: submillimeter survey of a well-studied piece of sky
• RMS astronomy: collective term for radio, millimeter, and submillimeter
• SCUBA: submillimeter instrument on James Clark Maxwell Telescope
• Submillimeter Array: radio interferometer in Hawaii
• submillimeter astronomy: astronomy observation and analysis of borderline infrared EMR
• submillimeter galaxy: galaxy that produces significant submillimeter radiation
• submillimeter galaxy designator: designation system of submillimeter galaxies
• Submillimeter Telescope: 10-meter far-infrared telescope
• Submillimeter Wave Astronomy Satellite: submillimeter space telescope operating 1998-2004
• Swedish-ESO Submillimetre Telescope: former 15 m radio telescope array in Chile
• Submillimeter Array: radio interferometer in Hawaii
  • East Asian Observatory: operator of JCMT
• submillimeter astronomy: astronomy observation and analysis of borderline infrared EMR
  • far infrared: infrared radiation with wavelengths in the 30-450 μm range
• submillimeter galaxy: galaxy that produces significant submillimeter radiation
  • AMUSE²: survey of ELANs
  • luminous infrared galaxy: a galaxy emitting a lot of far-infrared light
• submillimeter galaxy designator: designation system of submillimeter galaxies
• submillimeter source: see source
• Submillimeter Telescope: 10-meter far-infrared telescope
• Submillimeter Wave Astronomy Satellite: submillimeter space telescope operating 1998-2004
• submillimeter-selected galaxy (submillimeter galaxy): galaxy that produces significant submillimeter radiation
• submillimetre astronomy (submillimeter astronomy): astronomy observation and analysis of borderline infrared EMR
• Submillimetre Common-user Bolometer Array (SCUBA): submillimeter instrument on James Clark Maxwell Telescope
• submoon (subsatellite): object orbiting a moon
• Suborbital Polarimeter for Inflation Dust and the Epoch of Reionization (SPIDER): 2015 balloon-borne observatory to observe CMB polarization
• subradio: electromagnetic radiation, frequency below 3 kHz
  • extremely low frequency: electromagnetic radiation, frequency 3 Hz to 30 Hz
  • super low frequency: electromagnetic radiation, frequency 30 Hz to 300 Hz
  • tremendously low frequency: presumably electromagnetic radiation, frequency below 3 Hz
  • ultra low frequency: electromagnetic radiation, frequency 300 Hz to 3 kHz
  • very low frequency: electromagnetic radiation, frequency 3-30 kHz
• subsatellite: object orbiting a moon
• subsolar point: see substellar point
• subsonic
• Mach number: ratio of flow-speed to sound-speed
• substar (substellar object): star-like object with less mass than a star
• substar: see brown dwarf
• Substellar and Planetary Atmospheric Radiation and Circulation: see MITgcm
• substellar object: star-like object with less mass than a star
  • free-floating planet: planet that is not orbiting a star
  • WISE 0855-0714: nearby brown dwarf
• substellar point: point on a body such that a particular star is at the zenith
• subsumption band: see Europa
• SUDA: see Europa Clipper
• Sudbury Neutrino Observatory: Canadian underground neutrino detector
• sudden ionospheric disturbance: see solar storm
• SUFI: see SUNRISE
• sugars
• Lego principle: principle that life is associated with a skew in molecule abundances
• SUGRA (supergravity): combination of general relativity and supersymmetry
• SUGRA: see supersymmetry
• SUIT: see Aditya-L1
• sulci: see Enceladus
• sulfide: see geochemistry
• sulfur: metal, S, atomic number 16
  • geochemistry: the chemistry of the Earth, planets, and moons
  • oxygen burning: fusion reaction starting with oxygen
  • silicon burning: alpha process fusion starting at silicon
• sulfur dioxide
• Venus: second inner-most planet in the solar system
• Sulfur II: see sulfur
• sulfuric acid
• Venus: second inner-most planet in the solar system
• SUMER: see Solar and Heliospheric Observatory
• summer solstice: see solstice
• SUMSS: see MOST­
• Sun: star at center of solar system
  • Aditya-L1: 2023 spacecraft viewing Sun and analyzing solar wind
  • astronomical unit: about 93 million miles
  • atmosphere: gas surrounding astronomical object
  • Big Bear Solar Observatory: US government sponsored solar observatory
  • chromosphere: middle layer of the Sun's atmosphere
  • chromospheric activity index: measure of magnetic activity of a star's chromosphere
  • CLE: code to synthesize polarized emission lines of the solar corona
  • convection zone: region of a star transmitting energy through convection
  • corona: plasma surrounding a star
  • coronal hole: cool, low-density portions of the Sun's corona
  • coronal loop: visible loop extending out of the Sun's surface and back
  • coronal mass ejection: mass of plasma ejected from the Sun
  • COSIE: EUV spectrograph to analyze the corona
  • Coupled Ion-Neutral Dynamics Investigation: space weather investigation instruments on USAF spacecraft
  • CubIXSS: solar spectrometer satellite concept
  • ecliptic: path of the Sun on the celestial sphere as seen from Earth
  • ecliptic coordinate system: celestial coordinate system system based upon Earth's orbital plane
  • ESIS: EUV spectrograph for solar corona observation
  • facula: bright spot on a planet or the Sun
  • faint young Sun paradox: Earth had liquid water when it should have been too cold
  • flux rope: rope-shaped structure in magnetic fields associated with coronal mass ejections
  • Fraunhofer lines: dark lines discovered in the Sun's spectrum two centuries ago
  • galactic coordinate system: celestial coordinate system system based upon the galactic plane
  • Genesis: NASA spacecraft that returned solar wind particles
  • geomagnetic storm: disturbance in Earth's magnetosphere
  • insolation: solar energy received per unit area in given time
  • International Active Sun Years: 1969-1971 initiative for solar surveys
  • International Celestial Reference System: standardized variation of equatorial coordinate system
  • International Quiet Sun Year: 1964-1965 initiative for solar surveys
  • Large Earth-based Solar Telescope: 1990s plan for 2.4 m solar telescope
  • magnetic arcade: series of arch-like magnetic flux lines on the Sun
  • magnetic dipole radiation: EMR naturally generated by a spinning magnetic dipole
  • magnetic switchback: Z-shaped magnetic field lines
  • Maunder Minimum: 1600s-1700s period of fewer sunspots
  • Moreton wave: type of wave moving across the chromosphere
  • National Solar Observatory: US government sponsored solar observatory
  • Parker Solar Probe: space probe investigating solar corona
  • Parker wind: model of the solar wind
  • phase angle: view angle of reflected light implied by the phase of the Moon
  • radiation zone: region of a star transmitting energy through radiative diffusion
  • Solar and Heliospheric Observatory: satellite observing the Sun
  • solar apex: direction that the Sun is moving compared to nearby stars
  • solar circle: Sun's orbit around the Milky Way
  • solar constant: flux from the Sun at 1 AU
  • solar day: length of a solar system planet or Moon's day
  • Solar Dynamics Observatory: 2010 satellite observing the Sun
  • solar eclipse: eclipse consisting of the Moon blocking the Sun from view
  • solar energetic particle: high-energy particles from the Sun
  • solar eruption: sudden brightening of the Sun
  • solar flare: sudden brightening of the Sun
  • Solar Influences Data Analysis Center: Royal Observatory of Belgium division on solar weather data
  • solar luminosity: luminosity unit representing the luminosity of the Sun
  • solar mass: mass unit representing the mass of the Sun
  • Solar Mesophere Explorer: 1980s Earth atmospheric ozone research satellite
  • solar neighborhood: Milky Way in the vicinity of the Sun
  • solar neutrino: neutrino from the Sun
  • Solar Orbiter: space probe investigating the Sun's surface and the heliosphere
  • solar particle: particles from the Sun such as the solar wind
  • solar particle event: episode of higher velocity solar wind
  • solar physics: study of the physics of the Sun
  • solar storm: general term for events on the Sun
  • solar system: the Sun and what's gravitationally bound to it
  • solar system object: the Sun, solar system planets, minor planets, comets, and moons
  • solar telescope: telescope designed to observe the Sun
  • solar time: time based upon the position of the Sun in the Earth's sky
  • solar wind: charged particles emanating from the Sun
  • solstice: moment when Sun reaches its northern- or southern-most position
  • space weather: varying conditions in space affecting Earth and humans
  • spicule: small temporary jet from Sun's surface
  • standard model of a flare: description of how solar flares function
  • Sun surface features: features on the Sun's surface
  • SUNRISE: balloon-borne 1 m solar telescope
  • sunspot: temporary darker region of the Sun's surface
  • TIMED: space probe observing Earth upper atmosphere for solar effects
  • TRACE: former solar observing satellite
  • transition region: middle layer of the Sun's atmosphere
  • Ulysses: space mission to observe the Sun from off the ecliptic
  • Wind: spacecraft measuring solar wind
  • zodiacal light: sunlight reflected off interplanetary dust
• Sun surface features: features on the Sun's surface
• Sun-grazing comet: see long-period comet
• SUNGG: see The Survey for Ionization in Neutral Gas Galaxies
• sunquake: see quake
• SUNRISE: balloon-borne 1 m solar telescope
• SUNRISE I: see SUNRISE
• SUNRISE II: see SUNRISE
• SUNRISE III: see SUNRISE
• sunspot: temporary darker region of the Sun's surface
  • coronal loop: visible loop extending out of the Sun's surface and back
  • Maunder Minimum: 1600s-1700s period of fewer sunspots
• sunspot cycle: see sunspot
• Sunspot Index Data Center (Solar Influences Data Analysis Center): Royal Observatory of Belgium division on solar weather data
• sunspot number: see sunspot
• Sunspot Solar Observatory
• National Solar Observatory: US government sponsored solar observatory
• sunspots
• Sun surface features: features on the Sun's surface
• Sunyaev-Zel'dovich Array: array of eight 3.5 meter microwave telescopes
  • Owens Valley Radio Observatory: group of radio telescopes in California near the VLBA
• Sunyaev-Zel'dovich effect: type of distortion of the CMB
• super giants: see extra-solar planet
• Super Kamiokande Neutrino Detection Experiment: see Kamioka Observatory
• super low frequency: electromagnetic radiation, frequency 30 Hz to 300 Hz
• super Mercury: like the planet Mercury only larger
• super rotation: see zonal flow
• super-Earth: exoplanet more massive than Earth but substantially less than Neptune
  • 55 Cancri e: super-Earth orbiting a Sun-like star
  • GJ 1214 b: super-Earth extrasolar planet discovered in 2009
  • K2-18b: super-Earth in a habitable zone
  • Kepler-452b: Earth-like exoplanet discovered in 2015
  • LHS 3844 b: rocky planet in habitable zone of a red dwarf
  • mini-Neptune: planet with characteristics a bit like Earth but more like Neptune
  • OGLE-2005-BLG-390Lb: probable rocky planet orbiting red dwarf
  • Proxima b: exoplanet orbiting Proxima Centauri
• super-Eddington accretion: see Eddington luminosity
• super-Eddington accretion: see accretion
• super-Eddington luminosity: see Eddington luminosity
• super-Jupiters: see extra-solar planet
• Super-K: see Kamioka Observatory
• Super-Kamiokande: see Kamioka Observatory
• Super-LOTIS: see Livermore Optical Transient Imaging System
• super-Neptunes: see extra-solar planet
• super-pressure balloon: see SuperBIT
• Super-pressure Balloon-borne Imaging Telescope (SuperBIT): balloon-borne 0.5-m telescope
• super-puff: see super-Earth
  • Kepler-79: star with four super-puff planets
• SuperBIT: balloon-borne 0.5-m telescope
• SUPERBLINK: see Lépine Shara Proper Motion catalog
• superbubble: see shell
• superbubble: see supershell
• SuperCam: see Mars 2020
• SuperCDMS: see Cryogenic Dark Matter Search
• SuperCDMS SNOLAB: see Cryogenic Dark Matter Search
• SuperCDMS Soudan: see Cryogenic Dark Matter Search
• supercluster: cluster of galaxy clusters
• supercluster complex: see galaxy filament
  • supercluster: cluster of galaxy clusters
• superclusters
• galaxy cloud: substructure of a supercluster
• superconducting fluid
• neutron star: stellar remnant consisting entirely of solar masses of neutrons
• superconducting quantum interference device: type of very sensitive magnetometer using Josephson junctions
• superconducting quantum interference device (SQUID): very sensitive magnetometer
• superconducting tunnel junction: type of Josephson junction usable in EMR sensors
• superconductivity: see Cooper pair
• superconductor
• flux freezing: magnetic field lines becoming attached to plasma they pass through
• superconductor-isolation-superconductor: see superconducting tunnel junction
• supercooled state: see supercooling
• supercooling: cooling water below freezing point without it freezing
• SuperCOSMOS: see SuperCOSMOS Sky Survey
• SuperCOSMOS Hα Survey: see SuperCOSMOS Sky Survey
• SuperCOSMOS Sky Survey: survey of stars and galaxies from legacy plates
• SuperCOSMOS Sky Surveys (SuperCOSMOS Sky Survey): survey of stars and galaxies from legacy plates
• supercritical fluid: state of matter at sufficient pressure and temperature
• superearth (super-Earth): exoplanet more massive than Earth but substantially less than Neptune
• superflare
• stellar flare: sudden brightening of a star
• superfluid: fluid with no viscosity
  • Bose-Einstein condensate: rare state of matter possible at cryogenic temperatures
  • Bose-Einstein statistics: possible distribution of particles not bound by Pauli exclusion
  • neutron star: stellar remnant consisting entirely of solar masses of neutrons
• superfluidity: see superfluid
• supergalactic coordinate system: celestial coordinate system system based upon the supergalactic plane
  • celestial coordinate system: system for specifying position of celestial objects
• supergalactic latitude: see supergalactic coordinate system
• supergalactic longitude: see supergalactic coordinate system
• supergalactic plane: see supergalactic coordinate system
  • celestial coordinate system: system for specifying position of celestial objects
• supergiant: very large giant star
  • giant star: star larger than main sequence stars
• supergiant elliptical galaxy: see giant elliptical galaxy
• supergiant star (supergiant): very large giant star
• supergranulation: see Sun
• supergranule: see Sun surface features
• supergravity: combination of general relativity and supersymmetry
• supergravity: see supersymmetry
• superionic ice: odd state of water at high temperature and pressure
• superionic water (superionic ice): odd state of water at high temperature and pressure
• superionic water ice (superionic ice): odd state of water at high temperature and pressure
• superior conjunction: conjunction of an "superior planet", Mars, Jupiter, etc.
• superior planet: see heliocentric system
  • synodic period: period until a planet returns to the same position relative to the Sun
• superluminal motion: faster-than-light movement
• superluminous SN (superluminous supernova): stellar explosion larger than a supernova
• superluminous supernova: stellar explosion larger than a supernova
• supermassive BHMF: see black hole mass function
• supermassive binary black hole (binary SMBH): co-orbiting supermassive black holes
  • supermassive black hole: black hole with a mass of millions to billions of solar masses
• supermassive black hole: black hole with a mass of millions to billions of solar masses
  • binary SMBH: co-orbiting supermassive black holes
  • black hole: region of such high mass that light cannot escape
  • BlackHoleCam: European project to study black holes
  • NGC 1600: elliptical galaxy with large supermassive black hole
  • Romulus simulations: cosmological-simulation project active since circa 2015
• supermassive black hole binary (binary SMBH): co-orbiting supermassive black holes
  • supermassive black hole: black hole with a mass of millions to billions of solar masses
• supermassive black hole mass function: see black hole mass function
• supermassive black holes
• black hole accretion rate: measure, especially used for AGNs
• direct collapse black hole: theoretical means for quick formation of SMBHs
• SMBH formation: process by which SMBHs form
• supermassive neutron star: see hypermassive neutron star
• supermassive star: star more massive than stars normally form
• SuperNEMO: see KM3NeT
• supernova: stellar explosion larger than a nova
  • AT2018cow: unusual 2018 optical transient
  • Kepler's Supernova: Type Ia supernova observed in 1604 by Johannes Kepler
  • PSR B0950+08: young pulsar
  • SN 1572: Type Ia supernova noted in 1572 by Tycho Brahe
  • SN 185: supernova recorded in China in AD 185
  • SN 1987A: supernova in February 1987 rare for being visible by the naked eye
  • SN 1998bw: 1998 supernova with a coincident GRB
  • SN 2014J: Type Ia supernova in Messier 82, the Cigar Galaxy
• Supernova Acceleration Probe
• Roman Space Telescope: proposed near-infrared space observatory
• Supernova Cosmology Project: used supernova data to determine a history of the universe's expansion
• supernova designator: typical designation of supernovae
• Supernova Early Warning System: see supernova survey
• Supernova Factory Galaxy (NGC 2770): spiral galaxy that has shown a number of supernovae
• Supernova H₀ for the Equation of State (SH0ES): survey to increase the accuracy of the cosmic distance ladder
• supernova Hubble diagram: see Hubble diagram
• supernova impostor: extreme stellar explosion that does not destroy the star
• Supernova Legacy Survey: detect and monitor supernovae to measure the effects of dark energy
• supernova light curve: changing intensity of light following a supernova
• supernova nucleosynthesis: see nucleosynthesis
• supernova progenitor: the star or star system that produces a supernova
  • Type Ia supernova problem: lack of fully-convincing Type Ia supernovae triggering model
• supernova remnant: nebula of debris resulting from a supernova
  • 3C 397: supernova remnant discovered as a radio source
  • Antlia SN Remnant: dispersed supernova remnant in the constellation Antlia
  • Barnard's Loop: emission nebula in Orion
  • Cassiopeia A: supernova remnant visible for 300 years
  • Crab Nebula: supernova remnant in Taurus
  • Cygnus Loop: supernova remnant in Cygnus
  • G1.9+0.3: recent supernova remnant in Sagittarius
  • N 103B: supernova remnant in the LMC
  • Puppis A: supernova remnant bright in X-ray
  • supernova: stellar explosion larger than a nova
  • Vela supernova remnant: nearby supernova remnant
• supernova search (supernova survey): survey to identify and/or study supernovae
• supernova survey: survey to identify and/or study supernovae
• supernovae
• All Sky Automated Survey for SuperNovae: survey of both hemispheres for supernovae
• Asiago Supernova Catalog: catalog of known supernovae and their galaxies
• Calán/Tololo Supernova Survey: late 1980s to early 1990s search to redshift 0.1
• Carnegie Supernova Project: survey of supernovae lightcurves
• core collapse supernova: supernova resulting from the collapse of the core of a star
• Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey: early-universe survey by HST
• Dark Energy Survey: survey aimed at mapping the universe's expansion
• delay time distribution: characterization of interval from star formation until some type of event
• electron capture supernova: supernova from collapse of iron-free stellar cores
• ESSENCE: survey using supernova data to study dark energy
• GR1D: core collapse supernova simulation in 1D with GR
• GRB-supernova: supernova that produces a GRB
• guest star: translation of ancient Chinese term for a visible transient
• International Supernova Network: SN information sharing initiative
• ITEP-SAI Supernova Light Curve Catalogue: online catalog
• LaSilla-QUEST Variability Survey: survey for transients
• Latest Supernovae: recent supernova info collected
• Lick Observatory Supernova Search: search for supernovae for cosmological study
• magnetorotational supernova: type of core collapse supernova
• Mazurek's law: the effect of tweaking parameters is counterbalanced by feedback
• MOSFiT: code to match light-curves with light-curve models
• Multi-Epoch Nearby Cluster Survey: Type Ia supernova survey in clusters at z = 0.1
• near-Earth supernova: supernova near enough to Earth to affect it
• Nearby Supernova Factory: survey that scanned transient data for supernovae
• Pantheon: catalog of well-checked Type Ia supernovae
• radio supernova: supernova that includes a detectable radio emission
• SH0ES: survey to increase the accuracy of the cosmic distance ladder
• SPIRITS: Spitzer survey designed to find transients
• star formation feedback: mechanisms whereby star formation regulates its own rate
• Supernova Cosmology Project: used supernova data to determine a history of the universe's expansion
• supernova designator: typical designation of supernovae
• Supernova Legacy Survey: detect and monitor supernovae to measure the effects of dark energy
• supernova progenitor: the star or star system that produces a supernova
• supernova remnant: nebula of debris resulting from a supernova
• supernova survey: survey to identify and/or study supernovae
• Swope Supernova Survey: survey of low-redshift Type Ia SN light curves
• Type Ia supernova: type of supernova for which distance can be determined
• Type Ia supernova problem: lack of fully-convincing Type Ia supernovae triggering model
• WISeREP: interactive catalog of supernovae
• Wolf-Rayet supernova: identified by rapidly expanding carbon, oxygen and neon
• superparticle: see supersymmetry
  • neutralino: proposed type of particle that might include WIMPs
• superposition: see linear theory
• superradiance: exotic quantum-mechanics light-amplification phenomenon
• superrotating jet: see superrotating wind
• superrotating wind: wind traveling in the same direction as the planet is rotating
• supershell: very large ISM shell-shaped region
• supershell: see shell
  • HI supershell: large shells bordered by HI regions
• supersonic
• Mach number: ratio of flow-speed to sound-speed
• supersonic parachute
• drogue chute: parachute to slow something moving at high speed
• superstring theory: version of string theory including supersymmetry
• supersymmetry: extension to standard model of particle physics
  • neutralino: proposed type of particle that might include WIMPs
  • PICO experiment: a search for a candidate dark matter particle
  • supergravity: combination of general relativity and supersymmetry
• supervoid
• void: empty spaces between large scale structures
• SuperWASP: broad Earth-based search for transiting planets
  • WASP-12b: retrograde hot Jupiter discovered in 2008
  • WASP-43b: hot Jupiter with especially small orbit
• SuperWASP North
• WASP-33b: hot Jupiter discovered in 2010
• SuperWASP-North: see SuperWASP
• SuperWASP-South: see SuperWASP
• superwind: see stellar wind
  • asymptotic giant branch: a second stage of helium burning in some stars
• SUPOS: see SUNRISE
• supply-limited weathering: see weathering
• supramassive neutron star: see hypermassive neutron star
• suprathermal: having more energy than would be created by thermal excitation
• suprathermal electron: see suprathermal
• suprathermal ion: see suprathermal
• suprathermal particle: see suprathermal
• suprathermal tail: see suprathermal
• Suprime-Cam: see Subaru Telescope
  • Subaru XMM-Newton Deep Survey: survey using the Subaru telescope and XMM-Newton
• Suprime-cam
• Subaru Deep Field: survey of a small region of the sky using the Subaru telescope
• surface
• surface temperature: temperature of the surface of a star or planet
• surface abundance: quantity such as mass per surface area
• surface brightness: brightness per unit area of a surface
  • Arakelian Catalog: 1970s list of small/bright galaxies
  • de Vaucouleurs' profile: relation between elliptical galaxy surface brightness and distance from center
  • radiance: measure of EMR to/from a solid angle through an area
  • Sérsic profile: model of the relative surface brightness across a galaxy
• surface brightness fluctuation: apparent indication of an elliptical galaxy's distance
• surface brightness fluctuations method: see surface brightness fluctuation
• surface brightness profile: curve of a galaxy's brightness from center to edge
• surface brightness profile: see Sérsic profile
  • de Vaucouleurs' profile: relation between elliptical galaxy surface brightness and distance from center
• surface brightness sensitivity: see point source sensitivity
• surface density: quantity such as mass per unit area
  • column density: measure of the matter through which EMR is passing
• surface error: see wavefront error
• surface gravity: measure of gravity at the surface of a body
• surface gravity determination: see surface gravity
• surface of last scattering: sphere around us from which CMB photons are just reaching us
  • baryon acoustic oscillations: density fluctuations stemming from acoustic waves in the early universe
• surface plasmon: see plasmon
• surface reaction: such as reactions between gas and adjacent liquid
• surface temperature: temperature of the surface of a star or planet
  • stellar temperature determination: methods by which the temperature of a star is determined
• survey (astronomical survey): project collecting astronomical data
  • 1 Jansky Empty Field Survey: 1980s survey to find optical identifications for weak radio sources
  • 2dF Galaxy Redshift Survey: imaging survey of 300,000 extragalactic objects
  • 2dF-SDSS LRG and QSO survey: spectroscopic survey of distant galaxies
  • 3D-HST: near-infrared survey of 100,000 galaxies by HST
  • 6dF Galaxy Survey: UKST survey of galaxies in the southern sky
  • 8 pc: survey of stars within 8 parsecs, using coronagraph
  • 87GB Catalog of Radio Sources: 1980s Green Bank radio survey
  • AEGIS: early 2000s survey study of distant galaxies
  • AFGL Four Color Infrared Sky Survey: 1970s infrared survey
  • AIM-CO: survey of CO from star-forming epoch
  • ALFALFA: HI survey of many galaxies
  • All Sky Automated Survey: Polish survey of 20 million objects brighter than 14 magnitude
  • All Sky Automated Survey for SuperNovae: survey of both hemispheres for supernovae
  • ALMA-PILS Survey: millimeter survey of a protostar
  • ALMACAL: galaxy survey using ALMA calibration observations
  • AMUSE²: survey of ELANs
  • APASS: down to 16 magnitude
  • APM Galaxy Survey: 1990s survey of galaxies in southern sky
  • APOGEE: SDSS near-infrared survey of stars
  • Arecibo Occultation Survey: 1960s radio survey using occultations by the Moon
  • ASPECS: millimeter survey of HUDF
  • Astrographic Catalog: historical star catalog of the whole sky to magnitude 11
  • Atacama B-Mode Search: 2012-2014 survey of the CMB
  • Atlas 3D: survey of local galaxies
  • ATLAS survey: survey to find NEOs
  • Australia Telescope Large Area Survey: radio survey of two survey fields
  • Badgerys Creek Interferometer 101-MHz Survey: early 1950s survey of southern-hemisphere radio sources
  • Baryon Oscillation Spectroscopic Survey: survey of spatial distribution of luminous red galaxies and quasars
  • BASS: survey of AGNs found by the Swift BAT
  • BATC: photometric survey of Milky Way stars
  • BEAST: survey of B stars for possible exoplanets
  • BICEP2: survey to measure the polarization of the CMB
  • BigBOSS: BOSS survey follow-on
  • Bologna Survey of Radio Sources: 1970s-1980s radio survey
  • Breakthrough Listen: SETI survey using GBT and Parkes Observatory
  • Bruce Proper Motion Survey: 1941 southern-hemisphere survey catalog of Luyten's
  • C-BASS: 6 cm survey of the entire sky
  • Calán/Tololo Supernova Survey: late 1980s to early 1990s search to redshift 0.1
  • CALIFA: spectroscopic map of 600 galaxies
  • California-Kepler Survey: follow-up to Kepler to determine stellar radii
  • Campo Imperatore Near-Earth Object Survey: survey of near-Earth objects
  • Canada-France High-z Quasar Survey: 2000s distant quasar survey
  • Canada-France Redshift Survey: 1990s survey of galaxies to z = 1 to find associations of redshift to characteristics
  • Canadian Cluster Comparison Project: multi-wavelength survey of fifty X-ray-selected galaxy clusters
  • CAPMAP: early 2000s array that surveyed CMB polarization
  • CARMA EDGE: survey CO-mapping galaxies
  • Carnegie Supernova Project: survey of supernovae lightcurves
  • Case-Hamburg Survey: 1950s-1970s survey(s) of OB stars
  • Catalina Sky Survey: survey of near-Earth objects
  • CEERS: JWST early release observation program covering the EGS
  • CfA Redshift Survey: 1970s-1990s surveys of galaxy redshifts
  • CFBDS: survey in search of brown dwarfs
  • CFHTLS: surveys of transients and stars
  • Chandra Deep Field North: X-ray deep survey encompassing HDF region
  • Chandra Deep Field South: X-ray deep survey encompassing HDF-South region
  • Chinese Pulsar Timing Array: group of pulsars timed by FAST
  • CIBER: sounding-rocket survey of near-infrared background
  • Cluster Lensing and Supernova survey with Hubble: c2010 HST survey of galaxy cluster lensing
  • COCONUTS: survey to image companions of stars
  • COLD GASS: survey of CO in nearby large galaxies
  • COMPLETE Survey: survey of star forming regions
  • COPSS: survey of CO from star forming epoch
  • Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey: early-universe survey by HST
  • Cosmic Evolution Survey: investigation of dark matter and the universe's large scale structure
  • Cosmic Lens All-sky Survey: 1990s/2000s radio survey aimed at gravitational lensing
  • COSMOSOMAS: 1990s-2000s microwave survey
  • COUP: survey of X-ray sources in the Orion Nebula
  • CRATES: catalog of 8.4 GHz data on radio sources
  • CTIO Upper-Scorpius OB Association Survey: survey of low-mass stars and brown dwarfs
  • Dark Energy Survey: survey aimed at mapping the universe's expansion
  • DASCH: project to digitize Harvard astronomy plates
  • DECaLS: survey imaging part of SDSS footprint with DECam
  • Deep Ecliptic Survey: late 1990s/early 2000s survey for KBOs
  • Deep Multicolor Survey: 1990s optical and infrared deep survey
  • DEEP2: redshift survey of 60,000 galaxies
  • DeGaS-MC: APEX survey of potential star formation regions in the Magellanic Clouds
  • DENIS: 1990s southern sky survey of two near-infrared bands
  • DEVILS: visible-light spectrographic survey of 56k distant galaxies
  • Digitized Sky Survey: digitization of Palomar and UK Schmidt plates
  • Dominion Observatory 10.03 MHz Source Catalog: 1960s survey of northern-hemisphere radio sources
  • Dominion Observatory 1420 MHz Source Catalog: 1960s survey of northern-hemisphere radio sources
  • DSHARP: ALMA survey of imageable protoplanetary disks
  • Dwingeloo Obscured Galaxy Survey: radio survey of ZOA for 21-cm lines indicating galaxies
  • Dynamical Analysis of Nearby Clusters: survey of stars in stellar clusters
  • EDGES: survey aiming at highly-redshifted 21-cm detection
  • ELM Survey: survey of extremely-low-mass white dwarfs
  • EMPIRE Survey: survey of gas in M51a to follow up PAWS
  • EROS: search for MACHOs
  • eROSITA: Russian/German space X-ray telescope launched in 2019
  • ESO Nearby Abell Cluster Survey: 1990s spectroscopy and photometry survey of galaxy clusters
  • ESO/Uppsala Survey of the ESO (B) Atlas: 1970s southern all-sky survey
  • ESSENCE: survey using supernova data to study dark energy
  • Extended Chandra Deep Field-South Survey: 1100 square arcminute X-ray survey
  • F⁴: FRB followup project
  • Faint Infrared Grism Survey: survey to identify redshift of distant galaxies
  • FIRST: 1990s radio survey
  • FourStar Galaxy Evolution Survey: infrared deep-survey to detect galaxies
  • Fourth Cambridge Catalog of Radio Sources: 1960s catalog of northern hemisphere 178 MHz sources
  • Gaia: astrometry survey satellite launched in 2013
  • Galactic All-sky Survey: HI survey of the Milky Way
  • Galactic Emission Mapping: radio sky survey
  • GALAH: survey of Milky Way with an emphasis on old structures
  • Galaxy Evolution from Morphology and Spectral energy distributions: HST survey of galaxies with z in the range 0.2 to 1.2
  • Galaxy Zoo 2: crowd-sourced classification of hundreds of thousands of galaxies
  • GALEX Arecibo SDSS Survey: HI survey of many galaxies
  • GAMA: galaxy spectroscopy survey to roughly 1 Mpc
  • Giant Gemini GMOS survey: spectrographic survey of distant quasars
  • GLADE: list of galaxies likely to host GW events
  • GLARE: project to search for distant star-forming galaxies
  • GLEAM: MWA radio survey of the southern sky
  • Global Exoplanet M-dwarf Search-Survey: a search for exoplanets around m-dwarf stars
  • GMAN: collaboration to alert on microlensing transients
  • GOALS: across-spectrum observation of 200 LIRGs
  • GOODS: survey combining data from different sources on very distant objects
  • GOODS NICMOS Survey: survey with HST NICMOS instrument of galaxies in GOODS fields
  • Gould's Belt Distances Survey: survey of parallax distances to Gould's Belt YSOs
  • GPX: amateur effort to uncover exoplanets within the galactic plane
  • Green Bank 6-cm Radio Source Catalog: catalog of from 1980s northern-hemisphere radio survey
  • Ground-Base Electro-Optical Deep Space Surveillance: initiative to track artificial spacecraft including space junk
  • Group Evolution Multiwavelength Study: survey of galaxy groups
  • H3 Survey: spectroscopic survey of Milky Way halo stars
  • H₂O Southern Galactic Plane Survey: survey targeting water masers
  • Hamburg Schmidt Survey: photographic plates from the Hamburg Schmidt Camera
  • Hamburg/ESO Survey: 1990s southern hemisphere survey aimed at finding quasars
  • HATNet: distributed array of telescopes to search for transients
  • Hawaii K-band Galaxy Survey: near-infrared survey of a selection of fields
  • HBK: study of M31 globular clusters
  • Herschel Orion Protostar Survey: survey of SEDs of YSOs in Orion
  • Herschel Stripe 82 Survey: 70 square-degree survey of galaxies redshifted 1.8 to 3.5
  • HI 4-Pi Survey: HI map based upon EBHIS and GASS
  • HI Jodrell All-Sky Survey: northern-hemisphere HI survey carried out in late 90s/early 2000s
  • High Resolution Microwave Survey: 1990s microwave SETI search
  • High Time Resolution Universe Survey: c2010 search for pulsars and radio transients
  • HIPASS: HI survey carried out 1997 to 2002
  • HK Survey: 1985 search for metal poor-stars using calcium lines
  • Hubble Asteroid Hunter: Zooniverse effort to find asteroids in HST images
  • Hubble Deep Field: highly-detailed image of a small region of the sky taken with HST
  • Hubble Deep Field South: small region of the southern sky explored with HST
  • Hubble Heritage Project: effort assembling an archive of HST images
  • Hubble Ultra-Deep Field: extremely detailed HST image of a small region of space
  • Hydrogen Accretion in Local Galaxies Survey: radio survey looking for HI in galaxy halos
  • Indian Pulsar Timing Array: group of pulsars timed by the GMRT
  • International Active Sun Years: 1969-1971 initiative for solar surveys
  • International Geophysical Year: 1957-1958 initiative for geophysical and related astronomical research
  • International Quiet Sun Year: 1964-1965 initiative for solar surveys
  • International Space Year: 1992 initiative re space and astronomy
  • IPHAS: H-alpha survey
  • IRAC Shallow Survey: Spitzer survey of moderately wide field
  • JINGLE: survey of dust and gas in galaxies
  • KELT: pair of telescopes that searched for transients
  • Kepler-Swift Active Galaxies and Stars Survey: X-ray/UV survey of objects within the Kepler field
  • Kiso Survey of Ultraviolet Excess Galaxies: 1980 Japanese survey
  • KMOS3D: survey of galaxies before to after peak star formation
  • Korea Microlensing Telescope Network: survey searching for microlensing transients
  • LABOCA Extended Chandra Deep Field-South Submillimetre Survey: submillimeter survey of a well-studied piece of sky
  • Large Bright QSO Survey: 1980s quasar survey
  • Las Campanas Redshift Survey: 1990s survey of galaxies out to z = 0.2
  • LaSilla-QUEST Variability Survey: survey for transients
  • Lick Observatory Calcium Line Survey: 1980s survey of T-Tauri stars in the Taurus-Auriga Complex
  • Lick Observatory Supernova Search: search for supernovae for cosmological study
  • LINEAR: survey of near-Earth objects
  • Local Group Galaxy Survey: photometric survey of stars in a number of local group galaxies
  • LONEOS: survey of near-Earth objects
  • Lupus Transit Survey: survey for hot Jupiters in a region of constellation Lupus
  • LUX: experiment to identify WIMPs with a tank of xenon
  • MACHO Project: survey searching out microlensing that could indicate a MACHO
  • Magellanic Analog Dwarf Companions And Stellar Halos: Subaru survey for dwarf glaxies beyond the Local Group
  • Magellanic Catalogue of Stars: 1980s/1990s survey of stars in Magellanic Clouds
  • Magellanic Clouds Photometric Survey: UBVI survey of the Magellanic Clouds
  • MAPS: ALMA survey researching planet-formation
  • Markarian galaxy: list of galaxies with excess ultraviolet light
  • MASCARA: distributed array of telescopes to search for exoplanets
  • Massive Cluster Survey: survey of distant clusters evident in ROSAT X-ray data
  • MEarth Project: automated observatories monitoring nearby red dwarfs for transits
  • Medium Deep Survey: survey to find galaxies in HST WFPC2 images
  • MeerKAT Pulsar Timing Array: group of pulsars timed by MeerKAT
  • MeerKLASS: 21-cm-line survey using MeerKAT
  • Microlensing Planet Search: program to follow up on microlensing detections
  • MIGHTEE: radio survey of four established deep fields
  • Milky Way Mapper: SDSS spectrographic survey of Milky Way stars
  • Millennium Galaxy Catalogue: 2000s catalog of 10,000 galaxies
  • Millimeter-wave Intensity Mapping Experiment: project to map CO and [CII]
  • MISAO project: search for variable stars and transients
  • MOA: search for microlensing events
  • MOJAVE: program to monitor AGN jet radio brightness and polarization
  • Molecular Deep Field: survey of molecular lines in Hubble Deep Field
  • MORA: high resolution 2-mm survey of a portion of the COSMOS field
  • MOST­: radio telescope in New South Wales
  • Multi-Epoch Nearby Cluster Survey: Type Ia supernova survey in clusters at z = 0.1
  • Multi-instrument Aircraft Campaign: type of aircraft based study of meteor-shower-associated dust
  • Multiwavelength Survey by Yale-Chile: optical/NIR survey of four deep fields
  • Multiyear Interactive Computer Almanac 1800-2050: ephemerides app created by USNO
  • Munich Near-Infrared Cluster Survey: 1990s-2000s galaxy cluster survey
  • MUSCLES: HST UV survey of some M Dwarfs that host exoplanets
  • Nearby Supernova Factory: survey that scanned transient data for supernovae
  • NEAT: survey tracking near-Earth objects
  • NGTS: survey of transits from Chile
  • NRAO Catalog: 1960s follow-up to Cambridge radio surveys
  • NRAO VLA Sky Survey: 1990s microwave survey of 82% of the sky
  • OGLE: survey searching for microlensing transients
  • Ohio Radio Survey: 1960s radio survey by Ohio State University
  • Outer Solar System Origins Survey: 2013-2017 survey that searched for trans-Neptune objects
  • PALFA: Arecibo search for pulsars
  • PALMS: survey to find exoplanets for direct imaging
  • Palomar high-redshift quasar surveys: 1980s Hale-telescope quasar searches using new technology
  • Palomar Observatory Sky Survey: 1950s photographic plates from Palomar 48 inch telescope
  • Palomar Transient Factory: survey designed to find transients
  • Palomar-Green Survey: list of objects with excess ultraviolet light
  • Palomar-Leiden Survey: 1960s survey to identify distant asteroids
  • Pan-STARRS: set of survey telescopes
  • PanCET: HST UV/optical/NIR survey of selected exoplanets
  • PAndAS: survey of M31 and M33
  • Panoramic Imaging Survey of Centaurus and Sculptor: survey of extended halos of two nearby galaxies
  • Parkes Catalog: catalog of from 1960s-1990 of radio sources in southern hemisphere
  • Parkes HI Zone of Avoidance Survey: radio survey to identify galaxies hidden by the zone of avoidance
  • Parkes Multibeam Pulsar Survey: late 1990s radio survey in search of pulsars
  • Parkes Pulsar Timing Array: group of pulsars timed by Parkes Observatory
  • Parkes-MIT-NRAO Surveys: 1990 southern-hemisphere radio surveys
  • PAWS: survey of GMCs in M51a
  • PEP: survey aimed at star formation in early times
  • PESSTO: NTT survey following up on transients
  • PHANGS: set of surveys of nearby galaxies
  • PHAT: HST survey of M31 stars
  • PHIBSS: survey of CO in distant galaxies
  • Pi of the Sky: survey aimed at finding gamma-ray-burst visual counterparts
  • Pico dos Dias Survey: survey aimed to find T-Tauri stars
  • Planet Crossing Asteroid Survey: search for NEOs using small Palomar Schmidt Camera
  • POINT-AGAPE: survey of M31 for microlensing
  • POLARBEAR: instrument to map CMB polarization
  • Pre-OmegaTranS: transit search using MPG/ESO Telescope
  • PRIMUS: spectrographic survey of galaxies out to redshift 1
  • Probing Lensing Anomalies Network: survey that recorded microlensing event lightcurves
  • Qatar Exoplanet Survey: photometric survey that searched for transiting planets
  • QUaD: survey to measure the polarization of the CMB
  • QUBIC: survey measuring the polarization of the CMB
  • QUIET: survey to measure the polarization of the CMB
  • QUIJOTE: survey to measure the polarization of the CMB
  • Radio Galaxy Zoo: crowd-sourced classification of radio galaxies
  • REBELS: survey of star-forming galaxies during the reionization
  • REFINE: catalog of high-redshift galaxies
  • RESOLVE­: galaxy and gas survey limited to 65-100 Mpc
  • Rosat Bright Survey: list of bright X-ray sources from ROSAT observations
  • Rosat Hard Survey: list of hard X-ray sources from ROSAT observations
  • SAGE: survey of gas and dust in the Magellanic Clouds
  • Sagittarius Window Eclipsing Extrasolar Planet Search: transit search using HST time
  • SARAS: survey aiming at highly-redshifted 21-cm detection
  • Saskatoon: 1990s survey to measure CMB anisotropy
  • Second Byurakan Survey: 1970s-1990s survey of galaxies and quasars
  • SH0ES: survey to increase the accuracy of the cosmic distance ladder
  • SHARDS: GTC survey in GOODS-N field for quenched galaxies at z = 1 to 2.3
  • Simons Array: telescope array to map CMB polarization
  • SIMP: 2000s infrared proper-motion survey
  • SINS: near-infrared study of distant luminous galaxies
  • SKHB: survey of globular clusters in M31
  • SkyMapper Southern Survey: digital survey of the southern hemisphere sky
  • Sloan Digital Sky Survey: imaging survey of 500,000,000 objects in 35% of sky
  • Southern Sky Redshift Survey: 1980s/1990s redshift survey of southern galaxies
  • Southern Stellar Stream Spectroscopic Survey: spectroscopic survey of seven southern-hemisphere stellar streams
  • SPACEWATCH: survey to study minor planets
  • SPECULOOS: search for Earth-like exoplanets orbiting nearby dim stars
  • SPHEREx: all-sky spectral survey space-mission plan
  • SPIRITS: Spitzer survey designed to find transients
  • Spitzer Extended Deep Survey: survey of galaxy mass and black holes through life of the universe
  • Spitzer Extragalactic Representative Volume Survey: infrared survey of some well-studied fields
  • Spitzer HETDEX Exploratory Large Area Survey: Spitzer-based survey of galaxies
  • SPLASH: survey of M31's Giant Stellar Stream
  • STARE: array of radio telescopes monitoring radio transients
  • STARSMOG: survey of dust in galaxies
  • Stellar Planet Survey: astrometric search for planets around nearby stars
  • StrayCats: survey of X-ray sources detectable in NuSTAR stray light
  • Strong Source Surveys: series of 1970s/1980s 5 GHz surveys
  • Subaru Deep Field: survey of a small region of the sky using the Subaru telescope
  • Subaru XMM-Newton Deep Survey: survey using the Subaru telescope and XMM-Newton
  • SuperCOSMOS Sky Survey: survey of stars and galaxies from legacy plates
  • Supernova Cosmology Project: used supernova data to determine a history of the universe's expansion
  • Supernova Legacy Survey: detect and monitor supernovae to measure the effects of dark energy
  • SuperWASP: broad Earth-based search for transiting planets
  • Swope Supernova Survey: survey of low-redshift Type Ia SN light curves
  • Tenerife Experiment: 1980s-1990s survey of CMB anisotropies
  • Terra Hunting Experiment: search for exoplanets using HARPS3
  • TESS-Keck Survey: Keck follow-up survey to TESS discoveries
  • Texas Survey of Radio Sources at 365 MHz: 1970s/1980s radio survey made with the Texas Interferometer
  • The Amateur Sky Survey: amateur comet and variable-star search survey
  • The H2O Southern Galactic Plane Survey: survey of molecular clouds in the galactic plane
  • The Near Earth Space Surveillance Initiative: collaboration to survey NEOs
  • The Survey for Ionization in Neutral Gas Galaxies: survey of HI in galaxies found through the H-alpha line
  • Tianlai Project: 21-cm line intensity mapping project
  • Tomographic Ionized-carbon Mapping Experiment: instrument in development to map the [CII] line
  • Tonantzintla Surveys: surveys providing early images of quasars and Seyfert galaxies
  • Trans-Atlantic Exoplanet Survey: 2000s exoplanet-search survey using three telescopes
  • Transits of Extrasolar Planets: late 1990s search for transiting planets
  • Two Micron All-sky Survey: near-infrared survey of both hemispheres
  • Two Micron Sky Survey: 1969 infrared catalog produced by Caltech
  • UK Schmidt Survey: photographic survey of the southern hemisphere sky
  • UKIDSS: five-part infrared survey using UKIRT
  • Ultimate Spitzer Phase Curve Survey: investigation of exoplanet atmospheres
  • Ultraviolet Hubble Ultra-deep Field: ultraviolet data covering the Hubble Ultra Deep Field region of the sky
  • UltraVISTA: near infrared survey using VISTA telescope
  • Uppsala-ESO Survey of Asteroids and Comets: 1990s comet and asteroid survey
  • UTMOST: telescope aiming to detect radio transients
  • UVCANDELS: UV survey of CANDELS fields
  • VIMOS Public Extragalactic Redshift Survey: spectrographic redshift survey of 80,000 galaxies
  • VIMOS-VLT Deep Survey: spectroscopic survey of 100,000 high-redshift galaxies
  • VLASS: ongoing all-sky radio survey
  • VLT-FLAMES Tarantula Survey: VLT spectroscopic survey of massive stars
  • WASP: multi-university initiative to locate transiting planets
  • Westerhout Radio Survey: 1950s radio survey of the galactic plane
  • WFCAM Transit Survey: 2000s survey for exoplanet transits using UKIRT
  • WHISP: 1990s/2000s radio survey mapping HI density and velocity
  • Whole Earth Blazer Telescope: international initiative to gather blazar lightcurves
  • Whole Earth Telescope: international initiative to gather variable star lightcurves
  • WiggleZ: survey aimed at mapping dark energy
  • WINGS: all-sky survey investigating known galaxy clusters
  • WIYN Open Cluster Study: study begun in 2000 using the WIYN 3.5m Telescope
  • X-SHOOTER Lyman α survey at z = 2: survey of Lyman-α sources
  • XMM Cluster Survey: survey of existing XMM-Newton data to find galaxy clusters
  • XO Project: initiative to search for transiting planets
  • XQR-30: ESO-VLT quasar survey
  • ZEPLIN: experiment to identify WIMPs with a tank of xenon
  • Zwicky Transient Facility: survey designed to find transients
• Survey and Time-domain Astrophysical Research Explorer (STAR-X): plan for a future X-ray space telescope
• survey depth: indication of how far a survey reaches
• survey field: portion of the celestial sphere where a survey's observations aim
  • AEGIS: early 2000s survey study of distant galaxies
  • BDF: field used in search for distant galaxies
  • Boötes Field: moderate size survey field
  • Chandra Deep Field North: X-ray deep survey encompassing HDF region
  • Chandra Deep Field South: X-ray deep survey encompassing HDF-South region
  • D56: a target survey field of ACT telescope
  • Extended Groth Strip: region of sky searched for distant galaxies
  • GOODS: survey combining data from different sources on very distant objects
  • GOODS-North: moderate size survey field
  • GOODS-South: moderate size survey field
  • Groth Strip: region of sky in early HST survey
  • Hawaii K-band Galaxy Survey: near-infrared survey of a selection of fields
  • Hubble Deep Field: highly-detailed image of a small region of the sky taken with HST
  • Hubble Deep Field South: small region of the southern sky explored with HST
  • Hubble Ultra-Deep Field: extremely detailed HST image of a small region of space
  • Molecular Deep Field: survey of molecular lines in Hubble Deep Field
  • Stripe 82: SDSS field in southern hemisphere
  • Subaru Deep Field: survey of a small region of the sky using the Subaru telescope
  • Ultraviolet Hubble Ultra-deep Field: ultraviolet data covering the Hubble Ultra Deep Field region of the sky
• Survey for High-z Absorption Red & Dead Sources (SHARDS): GTC survey in GOODS-N field for quenched galaxies at z = 1 to 2.3
• Survey for Transient Astronomical Radio Emission (STARE): array of radio telescopes monitoring radio transients
• Survey of Ultraviolet Emission in Neutral-Gas Galaxies: see The Survey for Ionization in Neutral Gas Galaxies
• survey region (survey field): portion of the celestial sphere where a survey's observations aim
• survey-based designator: astronomical object designators based on name of survey
• Surveying the Agents of Galaxy Evolution (SAGE): survey of gas and dust in the Magellanic Clouds
• surveys
• astronomical catalog: list of observed astronomical bodies including characteristics
• astronomical survey: project collecting astronomical data
• blind survey: survey conducted independently of prior information
• cadence: period between observations
• CMB surveys: efforts studying the CMB
• completeness: measure of how many of a survey's objects of a certain magnitude have been detected
• deep field: survey field subject to lengthy observation to identify distant galaxies
• deep survey: survey using lengthy observation to identify distant galaxies
• Fsky: fraction of the sky, e.g., what a survey covers
• Hα survey: survey looking for the Hα line, typically to find star formation
• intensity mapping surveys: efforts mapping the intensity of spectral lines across the sky
• legacy survey: phrase sometimes used in survey names
• MAST: archive of data from surveys and missions
• QUEST: sixteen square-degree survey camera
• redshift space: concept of space using redshift as the radial dimension
• redshift survey: survey of the universe aiming at three dimensions
• scan speed: the speed at which the telescope changes angle on the sky while observing
• slew survey: survey conducted by imaging during a telescope's repointings
• Snapshot Program: short HST observation program aimed to fit between more substantial programs
• star count: surveys of stars counting them according to some criteria
• supernova survey: survey to identify and/or study supernovae
• survey depth: indication of how far a survey reaches
• survey field: portion of the celestial sphere where a survey's observations aim
• survey-based designator: astronomical object designators based on name of survey
• SUSI: optical interferometer in Australia
• SUSI: see SUNRISE
  • optical interferometer: interferometer of visible light
• SUSI-1: see New Technology Telescope
• SUSI-2: see New Technology Telescope
• SUSIM: see Upper Atmosphere Research Satellite
• SUSY (supersymmetry): extension to standard model of particle physics
• Sutherland Observatory: see South African Astronomical Observatory
• Sutherland Observing Station: see South African Astronomical Observatory
  • Infrared Survey Facility: 140 cm reflector telescope that images in infrared
  • MeerLICHT: South African telescope coordinated with MeerKAT
  • Southern African Large Telescope: 10-meter telescope in South Africa
• Sutherland Station: see South African Astronomical Observatory
• SUTRI: see Satech-01
• SuWt: see rare designator prefixes
• Suzaku: space X-ray telescope
• SVS: see rare designator prefixes
• SW: see rare designator prefixes
• SW effect (Sachs-Wolfe effect): gravitational redshift of the CMB
• SWA: see Solar Orbiter
• SWAN: see Solar and Heliospheric Observatory
• SWAP: see New Horizons
• SWAPI: see IMAP
• SWAS (Submillimeter Wave Astronomy Satellite): submillimeter space telescope operating 1998-2004
• SWASP (SuperWASP): broad Earth-based search for transiting planets
• SWAVES: see STEREO
• SWCam: see CCAT
• SWE (Sachs-Wolfe effect): gravitational redshift of the CMB
• SWE: see IMAP
• SWEA: see MAVEN
• SWEAP: see Parker Solar Probe
• Sweden
• Vetenskapsrådet: Swedish research council
• Swedish
• SMART-1: Swedish lunar orbiter operational 2003-2006
• Swedish Solar Telescope: see Roque de los Muchachos Observatory
  • refracting telescope: telescope using lenses rather than mirrors to magnify
• Swedish-ESO Submillimetre Telescope: 1990s 15 m submillimeter telescope in Chile
• Swedish-ESO Submillimetre Telescope: former 15 m radio telescope array in Chile
  • Africa Millimetre Telescope: planned 15 m radio telescope array in Namibia
• sweep signal (chirp): burst of signal rising or falling in frequency
• SWEEPS (Sagittarius Window Eclipsing Extrasolar Planet Search): transit search using HST time
• SWeffect (Sachs-Wolfe effect): gravitational redshift of the CMB
• SWEPAM: see Advanced Composition Explorer
• SWFO-L1: future NOAA space-weather warning satellite
  • ESA Vigil: plan for space-weather warning satellite at L5
• SWI: see JUICE
• SWI: see double star designation
• SWIA: see MAVEN
• SWICS: see Advanced Composition Explorer
• SWICS: see Ulysses
• Swift: satellite for studying gamma-ray bursts
  • BASS: survey of AGNs found by the Swift BAT
  • BAT6: sample of long GRBs
  • Kepler-Swift Active Galaxies and Stars Survey: X-ray/UV survey of objects within the Kepler field
• Swift Gamma-Ray Burst Mission (Swift): satellite for studying gamma-ray bursts
• Swift/BAT6 (BAT6): sample of long GRBs
• SWIMS: see Advanced Composition Explorer
• SWIMS: see Subaru Telescope
• SWIMS: see University of Tokyo Atacama Observatory
• swing-by (gravity assist): method of boosting the speed of a spacecraft
• SWiPS: see SWFO-L1
• SWIRC: see MMT
• SWIRE: see Spitzer Space Telescope
• Swiss T70 Telescope: see TRAPPIST
• switchback (magnetic switchback): Z-shaped magnetic field lines
• SWMF: software package of tools for modeling space weather
• SWOOPS: see Ulysses
• Swope Supernova Survey: survey of low-redshift Type Ia SN light curves
• Swope Telescope: see Las Campanas Observatory
  • 1 Jansky Empty Field Survey: 1980s survey to find optical identifications for weak radio sources
  • Magellanic Clouds Photometric Survey: UBVI survey of the Magellanic Clouds
  • Swope Supernova Survey: survey of low-redshift Type Ia SN light curves
• Swordy plot: well-known diagram plotting cosmic ray flux to particle energy
  • cosmic rays: very-high-energy particles from beyond the solar system
• SWP: see International Ultraviolet Explorer
• SWR: see International Ultraviolet Explorer
• SwRI (Southwest Research Institute): Texas research organization
• SWS: see Infrared Space Observatory
• SWS: see International Ultraviolet Explorer
• SX Arietis variable: see variable star
• SX Phoenicis variable: see variable star
• SXARI: see variable star
• SXC: see High Energy Transient Explorer
• SXDF: see Subaru XMM-Newton Deep Survey
• SXDS (Subaru XMM-Newton Deep Survey): survey using the Subaru telescope and XMM-Newton
• SXG (Spektr-RG): Russian-German X-ray observatory launched in 2019
• SXI: see Hitomi
• SXI: see THESEUS
• SXP: see rare designator prefixes
• SXPHE: see variable star
• SXR: see X-ray source
• SXS: see Hitomi
• SXT: see AstroSat
• SXT: see Hitomi
• SXT: see Yohkoh
• SXT: see transient
• Sy (Seyfert galaxy): visible active galaxy
• Sy 1: see Seyfert galaxy
• Sy 2: see Seyfert galaxy
• Sy 3: see Seyfert galaxy
  • LINER: galaxy nucleus emitting spectral lines for ionized and neutral atoms
• SY-1 (Satech-01): Chinese experimental spacecraft
• Sydney University Molonglo Sky Survey: see MOST­
• Sydney University Stellar Interferometer (SUSI): optical interferometer in Australia
  • optical interferometer: interferometer of visible light
• symbiotic binary: giant star transferring mass to a somewhat distant companion
• symbiotic star (symbiotic binary): giant star transferring mass to a somewhat distant companion
• symbol
• Z+: symbol for ion or ion charge
• symbolic regression: automated model-building by tinkering with formulae
• symmetric mass ratio: see chirp mass
• symmetry breaking: loss of symmetry, such as due to loss of stability in a regime change
  • cosmic string: rent in spacetime
• symmetry energy: see valley of beta stability
• synapse
• machine learning: use of programs that extract their algorithms from data
• neural network: computer program structure inspired by the brain
• synchro-Compton (synchrotron self-Compton): charged particle cloud scattering its own synchrotron-produced photons
• synchro-Compton catastrophe: see synchrotron self-Compton
• synchronous orbit: orbit with angular velocity matching the rotation of the orbited body
• synchronous rotation: see rotation period
• synchronous rotation: see synchronous orbit
  • tidal locking: locked rotation of an orbiting body
• synchrotron
• synchrotron radiation: radiation emitted when high-speed charged particles are accelerated
• synchrotron emission (synchrotron radiation): radiation emitted when high-speed charged particles are accelerated
• synchrotron luminosity: see synchrotron radiation
• synchrotron maser: see maser
• synchrotron radiation: radiation emitted when high-speed charged particles are accelerated
  • electron scattering: any process that changes the course of an electron
  • non-thermal emission: EMR not due to a body's heat
  • self-absorption: EMR absorption by the same substance that emitted it
  • spectral index: power by which an object's flux depends on frequency
• synchrotron self-absorption: see self-absorption
• synchrotron self-absorption: see synchrotron radiation
• synchrotron self-Compton: charged particle cloud scattering its own synchrotron-produced photons
• synchrotron self-scattering: see synchrotron radiation
• synestia model: see Moon formation
• synodic day (solar day): length of a solar system planet or Moon's day
• synodic period: period until a planet returns to the same position relative to the Sun
  • orbital period: length of time for an orbiting object to complete one cycle
  • sidereal: relative to the fixed position of the stars
• synodic rotation period (solar day): length of a solar system planet or Moon's day
• synodic rotation period: see rotation period
  • synodic period: period until a planet returns to the same position relative to the Sun
• synoptic: general, covering everything
• synoptic astronomy (time-domain astronomy): observing and analyzing changes in astronomical objects
• synoptic astronomy: see synoptic
• synoptic meteorology: see synoptic
• Synthése d'Ouverture en Infra Rouge avec Deux Telescopes: see GI2T
  • optical interferometer: interferometer of visible light
• synthesis (nucleosynthesis): creation of atomic nuclei
• synthesis imaging (aperture synthesis): interferometry to simulate a larger aperture telescope
• Synthesis Telescope
• Dominion Radio Astrophysical Observatory: radio observatory in British Columbia, Canada
• synthetic aperture radar: method of using moving radar with a stationary target
• synthetic aperture telescope: see aperture synthesis
• synthetic field method: method of testing galaxy opacity
• synthetic photometry: deriving photometry-style data from spectroscopy
• synthetic spectrum: simulated spectrum, e.g., of a type of star
• SYO: see double star designation
• Sys-Rem: algorithm to remove systematics from light curve data
• SysRem (Sys-Rem): algorithm to remove systematics from light curve data
• System Requirements Review: see MDR/SRR
• systematic error: errors with non-random characteristics
  • sigma: indication of the confidence level of an experiment
• systematics: see systematic error
• systemic redshift: see systemic velocity
• systemic velocity: average velocity of grouped objects, such as a galaxy
• syzygy: see opposition
• SZ (Sunyaev-Zel'dovich effect): type of distortion of the CMB
• Sz: see rare designator prefixes
• SZ Array (Sunyaev-Zel'dovich Array): array of eight 3.5 meter microwave telescopes
• SZ effect (Sunyaev-Zel'dovich effect): type of distortion of the CMB
• SZ/CMB-Pol: see Fred Young Submillimeter Telescope
• SZA (Sunyaev-Zel'dovich Array): array of eight 3.5 meter microwave telescopes
  • Owens Valley Radio Observatory: group of radio telescopes in California near the VLBA
• SZE (Sunyaev-Zel'dovich effect): type of distortion of the CMB