Term Index (E)

Astrophysics (index)

about

Term Index (E)

E:
- electric field (E): electric force as distributed over a space
- ESO/Uppsala Survey of the ESO (B) Atlas: 1970s southern all-sky survey
- magnetic flux density (B): vector field describing magnetism in relation to the Lorentz force
- scale height (H): measure of exponential falloff
E ring:
- Enceladus: Saturn moon considered possible carrier of life
E-CDFS:
- MIGHTEE: radio survey of four established deep fields
E-ELT:
- European Extremely Large Telescope (E-ELT,ELT): 39-meter telescope under construction
- European Southern Observatory (ESO): organization operating telescopes in the southern hemisphere
- extremely large telescope (ELT): optical telescope with a 20+ meter aperture
E-mode:
- CMB polarization: effects of scattering and lensing on the CMB
- polarization modes: electric and magnetic aspects of the polarization of electromagnetic radiation
E-THEMIS:
- Europa Clipper: planned Europa space probe
e-VLBI:
- Earth-sized VLBI: ground-based VLBI with near-maximal baseline
- electronic very-long-baseline interferometry (e-VLBI): real-time VLBI using electronic links
EAGLE: simulation of galaxy formation and evolution
- European Extremely Large Telescope (E-ELT,ELT): 39-meter telescope under construction
EAGLE Project:
- EAGLE: simulation of galaxy formation and evolution
early:
- quenched galaxy: galaxy currently producing minimal stars
- spectral class: classification of spectrums of stars (O, B, A, etc.)
early galaxies:
- first galaxies: targeted highest red-shift galaxies showing little or no metal
early M dwarf:
- M dwarf: small, cool main-sequence star in stellar class M
early universe: from the Big Bang to recombination
- anisotropy: directional dependence such as temperature variation in the CMB
- baryon acoustic oscillations (BAO): density fluctuations stemming from acoustic waves in the early universe
- Big Bang: theoretical event when the universe expanded from a point
- Big Bang nucleosynthesis (BBN): creation of atomic nuclei in the very early universe
- Canadian Institute for Theoretical Astrophysics (CITA,ICAT): national research organization at University of Toronto
- cold dark matter (CDM): one of three types of "dark matter" theory
- Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS): early universe survey by HST
- cosmic microwave background (CMB): microwave radiation coming from every direction
- cosmic string: rent in spacetime
- dark age: interval when the universe's hydrogen atoms were neutral
- inflation: theorized rapid expansion of the very early universe
- initial fluctuation spectrum: the power spectral density of the early universe
- recombination: time when the universe's ionized hydrogen atoms neutralized
- Sunyaev-Zel'dovich effect (SZ effect,SZ,SZE): type of distortion of the CMB
early-type galaxy:
- galaxy: gravitationally-bound group of stars
early-type star:
- spectral class: classification of spectrums of stars (O, B, A, etc.)
Earth: third solar system planet from the Sun
- airmass: measure of Earth-atmosphere attenuation for a telescope observation
- apparent magnitude (m): magnitude as seen from Earth adjusted for Earth atmosphere
- astronomical unit (AU): about 93 million miles
- atm: unit of pressure
- atmospheric window: frequency bands in which the atmosphere passes electromagnetic radiation
- aurora: light produced by atmosphere and solar wind
- crustal magnetism: magnetic fields independent of a world's core magnetic field
- crustal plates: sections of the Earth's crust that move
- earthshine: reflected and emitted electromagnetic radiation from Earth
- 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
- equatorial coordinate system: latitude/longitude-like system for the celestial sphere
- equinox: times when tilt of Earth is neither toward or away from the Sun
- geomagnetic storm: disturbance in Earth's magnetosphere
- Hadley cell: circulation pattern of up at the equator, out, down, and back
- horizontal coordinate system: celestial coordinate system based upon horizon and north
- hydrology: study of the movement of water
- intertropical convergence zone (ITCZ): circulation pattern near equator where north and south Hadley cells meet
- ionosphere: layers of Earth atmosphere with significant ions
- Kelvin waves: pressure and gravity waves formed by Coriolis force and a barrier
- mass extinction: event in which many species went extinct
- moon: a planet's natural satellite, such as Earth's
- numerical weather prediction (NWP): Earth weather prediction by computer equation-solving and/or simulation
- paleomagnetism: ancient magnetic fields and their characteristics
- Rossby waves: meandors in high-altitude winds
- seismic waves: waves broadcast from earthquakes
- solar constant: flux from the Sun at 1 AU
- solstice: moment when Sun reaches its northern- or southern-most position
- strewn field: region with fragments of a meteor impact
- THEMIS: set of satellites studying the Earth's magnetic field
- Van Allen belts: regions of energetic charged particles surrounding Earth
- vegetation red edge (VRE): wavelength cut-off point in the reflectivity of typical plants
Earth mass:
- mass: object's quality that determines the effects of forces and gravity
Earth-sized VLBI: ground-based VLBI with near-maximal baseline
Earths:
- extra-solar planet: planet not in the solar system
earthshine: reflected and emitted electromagnetic radiation from Earth
EB:
- CMB polarization: effects of scattering and lensing on the CMB
EBHIS:
- Galactic All-sky Survey (GASS): HI survey of the Milky Way
EBL:
- cosmic background radiation (CBR): electromagnetic radiation coming from every direction
- extragalactic background light (EBL): electromagnetic radiation from star formation and AGNs
eBOSS:
- Baryon Oscillation Spectroscopic Survey (BOSS): survey of spatial distribution of luminous red galaxies and quasars
- Sloan Digital Sky Survey (SDSS): imaging survey of 500,000,000 objects in 35% of sky
eccentric anomaly:
- mean anomaly: angle describing an object's position within an elliptical orbit
eccentricity (e): degree to which an orbit is non-circular
- DQ Tau: young binary star system
- orbital element: parameters describing an orbit
ECDFS:
- DEVILS: visible-light spectrographic survey of 56k distant galaxies
- Extended Chandra Deep Field-South Survey (ECDFS): 1100 square arcminute X-ray survey
echelette grating:
- grating: spectrometer component
echelle grating:
- grating: spectrometer component
- HARPS: high-precision spectrograph for exoplanet searches
eclipse:
- celestial event: generally something happening visible in the sky
- occultation: one celestial body hiding another from an observer
- secondary eclipse: eclipse of a body that also transits
eclipse mapping: using eclipse light curves to map surface features
eclipse timing offset:
- secondary eclipse: eclipse of a body that also transits
eclipsing binary: binary star system detected by variations in magnitude
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
ecliptic latitude:
- ecliptic coordinate system: celestial coordinate system system based upon Earth's orbital plane
ecliptic longitude:
- ecliptic coordinate system: celestial coordinate system system based upon Earth's orbital plane
ecliptic plane:
- ecliptic: path of the Sun on the celestial sphere as seen from Earth
Ecliptic Plane Input Catalog:
- K2: second Kepler mission that worked around failed equipment
Eddington accretion rate:
- accretion: enlargement of an astronomical body by gravitationally attracting additional mass
- accretion rate: rate of addition of mass to an object
- Eddington luminosity: maximum luminosity at which radiation force overcomes gravity
Eddington approximation: approximation of a star's internal EMR's divergence from isotropic
Eddington bias: selection bias from mistaking something common for something rare
Eddington limit:
- Eddington luminosity: maximum luminosity at which radiation force overcomes gravity
Eddington luminosity: maximum luminosity at which radiation force overcomes gravity
Eddington-Barbier relation:
- source function (S): measure indicating the effect of a material on EMR passing through
eddy:
- turbulence: irregular flow of a fluid
Edgeworth-Kuiper Belt:
- Kuiper Belt (K Belt,KB): further part of solar system beyond Neptune
Edgeworth-Kuiper Belt object:
- Kuiper Belt (K Belt,KB): further part of solar system beyond Neptune
EE:
- CMB polarization: effects of scattering and lensing on the CMB
EE cosmic rays:
- cosmic rays (CR): very-high-energy particles from beyond the solar system
EECR:
- cosmic rays (CR): very-high-energy particles from beyond the solar system
EECRs:
- GZK limit: limit on energy of cosmic rays
EELG:
- emission line galaxy (ELG): a galaxy type characterized by emission lines
effective number of neutrinos:
- neutrino (ν): light, electrically neutral elementary particle
effective radius (R_e): radius of a galaxy within which 1/2 the light is emitted
effective temperature (T_eff,Teff): temperature of an equivalent black body in terms of total radiation
Effelsberg 100-m Radio Telescope: German large single-dish radio telescope
Effelsberg Radio Telescope:
- European Pulsar Timing Array (EPTA): European collaboration of radio telescopes
EFI:
- THEMIS: set of satellites studying the Earth's magnetic field
EFOSC2:
- New Technology Telescope (NTT): 3.58 meter reflecting telescope in Chile
- PESSTO: survey for transients carried out on the NTT
EGO:
- European Gravitational Observatory (EGO): gravitational wave observatory in Italy
EGRET:
- Compton Gamma Ray Observatory (CGRO): 1990s space observatory for gamma ray observation
EGS:
- Extended Groth Strip (EGS): region of sky searched for distant galaxies
Eh:
- event horizon (EH): surface-shape around a black hole through which light cannot escape
- reduction potential (Eh,ORP,pE): measure of a chemical species' tendency to acquire electrons
EHT:
- Event Horizon Telescope (EHT): growing VLBI network
eigen-decomposition:
- eigenvalue (λ): ratio between a vector and a linear transformation of that vector
eigenmode: vibration mode of an oscillator where all parts move at the same frequency
eigenmode decomposition:
- eigenmode: vibration mode of an oscillator where all parts move at the same frequency
eigenmode expansion:
- eigenmode: vibration mode of an oscillator where all parts move at the same frequency
eigenvalue (λ): ratio between a vector and a linear transformation of that vector
eigenvector:
- eigenvalue (λ): ratio between a vector and a linear transformation of that vector
Einstein angle:
- gravitational microlensing: gravitational lensing by "small" objects such as individual stars and planets
Einstein Observatory:
- HEAO-2: 1978 X-ray observatory space mission
Einstein parallax:
- gravitational microlensing: gravitational lensing by "small" objects such as individual stars and planets
Einstein radius:
- gravitational microlensing: gravitational lensing by "small" objects such as individual stars and planets
Einstein ring:
- gravitational microlensing: gravitational lensing by "small" objects such as individual stars and planets
Einstein Telescope: concept for a larger LIGO-like GW detector
Einstein's field equation:
- cosmological constant (Λ): force counteracting the universe's inward gravitational pull
- general relativity (GR): formula relating gravity, space, time, and mass
Einstein-de Sitter model: universe tuned to the smallest expansion that continues forever
Einstein-de Sitter universe:
- Einstein-de Sitter model: universe tuned to the smallest expansion that continues forever
Einstein-Rosen bridge:
- wormhole: connection between two regions in a curved space
EIS:
- Europa Clipper: planned Europa space probe
EIT:
- Solar and Heliospheric Observatory (SOHO): satellite observing the Sun
ejection: forcing or throwing something out
EKBO:
- Kuiper Belt (K Belt,KB): further part of solar system beyond Neptune
El Niño:
- Kelvin waves: pressure and gravity waves formed by Coriolis force and a barrier
ELAIS:
- Infrared Space Observatory (ISO): 1990s 60cm infrared space telescope
ELAIS-N1:
- Infrared Space Observatory (ISO): 1990s 60cm infrared space telescope
- Spitzer Extragalactic Representative Volume Survey (SERVS): infrared survey of some well-studied fields
ELAIS-N2:
- Infrared Space Observatory (ISO): 1990s 60cm infrared space telescope
ELAIS-N3:
- Infrared Space Observatory (ISO): 1990s 60cm infrared space telescope
ELAIS-S1:
- Infrared Space Observatory (ISO): 1990s 60cm infrared space telescope
- MIGHTEE: radio survey of four established deep fields
- Spitzer Extragalactic Representative Volume Survey (SERVS): infrared survey of some well-studied fields
ELAIS-S2:
- Infrared Space Observatory (ISO): 1990s 60cm infrared space telescope
elastic scattering:
- Thomson scattering: elastic scattering of photons by a charged particle
electric:
- electric field (E): electric force as distributed over a space
electric field (E): electric force as distributed over a space
electric potential:
- electric field (E): electric force as distributed over a space
electricity:
- Coulomb's law: static electrical force relation
- electric field (E): electric force as distributed over a space
- electromotive force (EMF): force that drives an electric current
- Hall effect: voltage generated by interacting current and magnetic field
- Maxwell's equations: four equations describing electricity and magnetism
- telegrapher's equations: two equations describing a transmission line
electromagnetic induction:
- magnetic induction: voltage across a conductor induced by changing magnetic field
electromagnetic radiation (EMR): radiation such as light, radio, X-rays
electromagnetic spectrum: spectrum of EMR
electromagnetism (EM): electricity and magnetism and their interaction
- Coulomb's law: static electrical force relation
- dielectric: insulator that responds to an electric field
- electric field (E): electric force as distributed over a space
- electromagnetic radiation (EMR): radiation such as light, radio, X-rays
- field lines: lines showing the pattern of a mathematical field
- jet current: electric current within a plasma jet
- magnetic induction: voltage across a conductor induced by changing magnetic field
electromotive force (EMF): force that drives an electric current
electron:
- baryon: protons, neutrons, and other three-quark particles
- beta decay: radioactivity such that an electron or positron is emitted
- particle: very small thing
- plasma frequency: frequency of electron plasma oscillation
- standard model: model of elementary particles including quarks
- supersymmetry: extension to standard model of particle physics
electron capture: combination of an electron with a proton
- neutronization: an electron and proton combining to form a neutron
electron degeneracy: the condition of electrons supported solely by the Pauli exclusion principle
electron degeneracy pressure:
- electron degeneracy: the condition of electrons supported solely by the Pauli exclusion principle
electron degenerate matter:
- electron degeneracy: the condition of electrons supported solely by the Pauli exclusion principle
electron excitation:
- atomic excitation: atoms with electrons above the ground state
electron neutrino:
- Mikheyev-Smirnov-Wolfenstein effect (MSW effect): neutrino oscillation between three flavors
- standard model: model of elementary particles including quarks
electron orbital: a nucleus's "locations" where an electron can orbit
electron pressure:
- number density: number of objects per volume
electron relaxation:
- atomic excitation: atoms with electrons above the ground state
electron scattering: any process that changes the course of an electron
- absorption: removal of photons from a beam of EMR
- Compton scattering: photon collision with a charged particle that emits a different photon
- Thomson scattering: elastic scattering of photons by a charged particle
electron screening: reduction of effective charge of a nucleus by nearby electrons
electron shell:
- hyperfine structure: spectral lines from magnetic and spin interactions between electrons and nucleus
electronic:
- Fast Fourier Transform Telescope: proposed all-digital telescope with synthetic aperture
electronic very-long-baseline interferometry (e-VLBI): real-time VLBI using electronic links
electronics:
- antenna temperature: parameter in determining noise introduced by an antenna
- back end instrument: instruments of a telescope that process or combine signals
- downconverter: device that reduces the frequency of a signal
- front end instrument: instruments of a telescope that detect and encode the signal
- noise temperature: a measure of noise in electronic devices
- thermal noise: noise inherent in electronic component warmer than absolute zero
electrostatic bond:
- ice: solid state of water
electroweak: single conception including both electromagnetic and weak forces
- strong force: force that holds quarks and nuclei together
electroweak force:
- electroweak: single conception including both electromagnetic and weak forces
- WIMP: proposed particle comprising dark matter
element: class of atom based on its number of protons
- calcium (Ca): element, Ca, atomic number 20
- carbon (C): element, C, atomic number 6
- fusion: formation of an atomic nucleus nuclei from multiple smaller nuclei
- helium (He): non-metallic element, He, atomic number 2
- hydrogen (H): most prominent element, atomic number 1
- iron (Fe): metal, Fe, atomic number 26
- lithium (Li): metal, Li, atomic number 3
- nickel (Ni): metal, Ni, atomic number 28
- nitrogen (N): metal, N, atomic number 7
- oxygen (O): element, O, atomic number 8
- silicon (Si): metal, Si, atomic number 14
- sodium (Na): metal, Na, atomic number 11
- sulfur (S): metal, S, atomic number 16
elevation range: measure of how high and low a telescope can be pointed
ELF:
- Enceladus Life Finder (ELF): mission to search for life on Saturn moon Enceladus
- extremely low frequency (ELF): electromagnetic radiation, frequency 3Hz to 30Hz
ELG:
- emission line galaxy (ELG): a galaxy type characterized by emission lines
ELHC:
- EROS: search for MACHOs
Elias 2-27: much-studied YSO
ELIRG:
- luminous infrared galaxy (LIRG): a galaxy emitting a lot of far-infrared light
eLISA:
- New Gravitational Wave Observatory (NGO): proposed space mission to detect gravitational waves
ellipse:
- conic section: orbit shapes, like the intersection of a plane and cone
- eccentricity (e): degree to which an orbit is non-circular
- Keplerian orbit: orbit following a perfect ellipse or other conic section
- orbital element: parameters describing an orbit
- semi-major axis (a): maximum radius of an ellipse
elliptical:
- 3C 327: elliptical radio galaxy
- galaxy merger: combination of galaxies upon collision
- Messier 84 (M84): elliptical galaxy with jets
elliptical galaxies:
- de Vaucouleurs' profile: relation between elliptical galaxy surface brightness and distance from center
- Faber-Jackson relation: relation between elliptical galaxy luminosity and stellar velocity dispersion
- fundamental plane: three-way relation between elliptical galaxy characteristics
- hypergalaxy: sizeable spiral galaxy with satellites
elliptical galaxy: ellipsoidal-shaped galaxy
- galaxy classification: morphological classification of galaxies
ellipticity:
- elliptical galaxy: ellipsoidal-shaped galaxy
elongation:
- heliocentric system: model of the universe with the planets orbiting the Sun
ELT:
- Colossus Telescope: concept for a 50-meter telescope using interferometry
- European Extremely Large Telescope (E-ELT,ELT): 39-meter telescope under construction
- extremely large telescope (ELT): optical telescope with a 20+ meter aperture
- Giant Magellan Telescope (GMT): 24.5 meter telescope under construction
- Giant Segmented Mirror Telescope (GSMT): concept for an extremely large telescope
- Overwhelmingly Large Telescope (OWL): 100m telescope plan
- Thirty Meter Telescope (TMT): extremely large telescope planned for Hawaii
EM:
- electromagnetism (EM): electricity and magnetism and their interaction
EM radiation:
- electromagnetic radiation (EMR): radiation such as light, radio, X-rays
embryo:
- planetary embryo: object that may grow into a future planet
embryo barrier: a barrier to accretion on the order of the size of Pluto
emergent gravity:
- modified Newtonian dynamics (MOND): alternative theory of gravity addressing "dark matter"
EMF:
- electromotive force (EMF): force that drives an electric current
EMIR:
- EMPIRE Survey: survey of gas in M51a to follow up PAWS
- Gran Telescopio Canarias (GTC): 10.4 meter telescope in the Canary Islands
EMIR Multi-line Probe of the ISM Regulating Galaxy Evolution:
- EMPIRE Survey: survey of gas in M51a to follow up PAWS
emission: addition of photons to a beam of EMR
- 21cm experiment: search for redshifted 21cm hydrogen emission lines
- 21cm line: hydrogen line useful for determining redshift
- continuum emission: continuous spectrum such as black body radiation or bremsstrahlung
- emission coefficient (j): measure of how much light a substance emits
- emission line: point of high intensity in a spectrum
- foreground subtraction: removing unwanted sources of EMR in intensity mapping
- intensity mapping: measure of cosmic matter density
- ionized carbon fine structure line ([CII]): carbon line that traces distant star formation
- PAH emissions: infrared emission from polycyclic aromatic hydrocarbons in gas clouds
emission band:
- spectral band: set of related, closely-packed spectral lines
emission coefficient (j): measure of how much light a substance emits
emission line: point of high intensity in a spectrum
emission line galaxy (ELG): a galaxy type characterized by emission lines
emission redshift:
- redshift (z): change to longer wavelengths due to Doppler affects
emission spectroscopy:
- transmission spectroscopy: spectrum of radiation passing through a substance
emissivity: measure of a material's efficiency at radiating thermal radiation
emissivity index:
- spectral index (α): power by which an object's flux depends on frequency
EMPIRE Survey: survey of gas in M51a to follow up PAWS
EMR:
- 21cm experiment: search for redshifted 21cm hydrogen emission lines
- AB system: monochromatic magnitude calibration based upon absolute values
- absolute magnitude (M): magnitude as seen from 10 parsecs
- absorption: removal of photons from a beam of EMR
- absorption coefficient: measure of how much light a substance absorbs
- active galactic nucleus (AGN): central region of a galaxy with extremely high luminosity
- albedo: measure of reflectance
- anomalous cosmic rays (ACR): cosmic rays with unexpectedly low energies
- aperture: opening through which light passes
- aperture synthesis: interferometry to simulate a larger aperture telescope
- apparent magnitude (m): magnitude as seen from Earth adjusted for Earth atmosphere
- atmospheric window: frequency bands in which the atmosphere passes electromagnetic radiation
- aurora: light produced by atmosphere and solar wind
- B: photometric filter for blue light
- bandwidth: number of hertz between minimum and maximum frequencies
- black body (BB): idealized object that reflects no light
- black-body radiation: continuous spectrum characteristic of the temperature of a body
- bolometer: instrument measuring heat produced by radiation
- bolometric correction: difference between an object's bolometric and visible magnitudes
- bolometric luminosity (L_Bol): total luminosity of an object at all wavelengths
- bolometric magnitude (Mbol,M_bol): absolute magnitude of all wavelengths
- bremsstrahlung: photon emission when a charged particle is decelerated
- Cherenkov radiation: radiation from the shock of a charged particle passing through a medium
- chirp: burst of signal rising or falling in frequency
- circular polarization ratio (CPR): ratio of circular polarization handedness in reflected radar signal
- CMB lensing: gravitational lensing of the CMB
- color index: a number that characterizes the color of an object
- color-color diagram: means of comparing characteristics of stars
- color-period diagram: means of comparing periods of stars at various wavelengths
- column density: measure of the matter through which EMR is passing
- Compton scattering: photon collision with a charged particle that emits a different photon
- continuum emission: continuous spectrum such as black body radiation or bremsstrahlung
- cooling function: function relating a gas's cooling rate to its temperature
- cosmic background radiation (CBR): electromagnetic radiation coming from every direction
- cosmic infrared background (CIB): widespread infrared radiation not associated with known sources
- cosmic microwave background (CMB): microwave radiation coming from every direction
- cosmic optical background (COB): widespread optical radiation not associated with known sources
- cosmic X-ray background (CXB,CXRB): X-ray radiation coming from outside the Milky Way
- cross dispersion spectrograph: echelle spectrograph with additional disperser crosswise to the first
- curvature radiation: synchrotron-like radiation when particles follow curved field lines
- cyclotron radiation: radiation emitted when charged particles are accelerated
- diffuse emission: electromagnetic radiation not confined to a point source
- distance modulus (u): apparent magnitude minus absolute magnitude
- Doppler broadening: broadening of spectral lines due to velocities of the photon sources
- Earth-sized VLBI: ground-based VLBI with near-maximal baseline
- earthshine: reflected and emitted electromagnetic radiation from Earth
- Eddington approximation: approximation of a star's internal EMR's divergence from isotropic
- effective temperature (T_eff,Teff): temperature of an equivalent black body in terms of total radiation
- electromagnetic radiation (EMR): radiation such as light, radio, X-rays
- electromagnetic spectrum: spectrum of EMR
- electronic very-long-baseline interferometry (e-VLBI): real-time VLBI using electronic links
- emission: addition of photons to a beam of EMR
- emission coefficient (j): measure of how much light a substance emits
- equation of radiative transfer (RTE): equation describing energy transfer by EMR
- equilibrium temperature (T_eq,Teq): temperature a planet would have if it were an externally-heated black body
- European VLBI Network (EVN): consortium of radio telescopes to coordinate VLBI efforts
- extinction: the absence of any radiation from an astronomical object because all is absorbed or scattered
- extragalactic background light (EBL): electromagnetic radiation from star formation and AGNs
- extreme ultraviolet (EUV,XUV): electromagnetic radiation in the range of 10nm-124nm
- extremely low frequency (ELF): electromagnetic radiation, frequency 3Hz to 30Hz
- far infrared (FIR): infrared radiation with wavelengths in the 30-450um range
- fast radio burst (FRB): astronomical high energy radio pulses of a few milliseconds
- fluorescence: mechanism by which molecules emit a longer wavelength than they absorb
- flux: flow rate per unit area
- foreground subtraction: removing unwanted sources of EMR in intensity mapping
- frequency: number of cycles per unit of time, such as waves per second
- frequency modulation (FM): changing the frequency of a signal's carrier
- G band: band of visible light around 5100 angstroms
- galaxy SED: SED of a galaxy, sometimes synthesized from photometric surveys
- gamma rays: electromagnetic radiation, wavelength 10 picometers and less
- gamma-ray burst (GRB): short flashes of gamma rays apparently from outside our galaxy
- gravitational lensing: focusing electromagnetic radiation by gravitational force
- gravitational microlensing: gravitational lensing by "small" objects such as individual stars and planets
- gravitational redshift: redshift due to GR effects of gravity
- greenhouse effect: mechanism that boosts temperature through selective blocking of EMR
- Gunn-Peterson trough: spectral feature in EMR from redshift 6+
- GZK limit: limit on energy of cosmic rays
- I band: photometric filter for near infrared light
- imaging Fourier transform spectroscopy (IFTS): Michelson-interferometer-based imaging spectroscopy
- imaging spectrometer: device to capture spectrum point-by-point of an image
- infrared (IR): electromagnetic radiation, wavelength .74-300 micrometers
- infrared cirrus: cirrus-cloud-like infrared emissions from dust, etc.
- integral field spectrograph: spectrograph that captures images
- integral field unit (IFU): instrument to allow a spectrograph to capture data over a 2d field
- intensity: power reaching a surface from a specific source
- intensity mapping: measure of cosmic matter density
- interferometer: device detecting properties of electromagnetic waves by detecting interference between waves
- irradiance: power reaching a surface
- jansky (Jy): unit of measurement of spectral flux density
- JHK photometric system (JHK): system to classify stars according to near-infrared colors
- K band: atmospheric window centered around 2.2 microns, or 136 THz
- K correction: correction to magnitude for redshift
- Kirchhoff's laws: laws regarding the source of spectral lines
- line shape function: function describing the shape of a spectral line
- low-surface-brightness galaxy (LSB galaxy): galaxies less bright than those historically identified
- luminosity (L): measure of brightness
- Lyman-Werner photon: ultraviolet photon with proper energy to excite molecular hydrogen
- magnetic dipole radiation: EMR naturally generated by a spinning magnetic dipole
- magnitude: a logarithmic measure of brightness
- maser: electromagnetic radiation amplified by stimulated emission
- microwave: electromagnetic radiation, frequency 300MHz to 300GHz
- mid infrared (MIR): infrared radiation with wavelengths in the 7.5um-25um range
- monochromatic luminosity: luminosity at a specific wavelength
- multi-object spectrograph: device to record the spectrum of multiple targets simultaneously
- multipole expansion: series expansion of a function over the surface of a sphere
- near infrared (NIR,near-IR): electromagnetic radiation in the range of 800-2500 nm
- OIR: a spectral "band name" for both visible light and infrared
- opacity: a measure of opaqueness of a material
- optical depth (τ): a measure of opaqueness of a path of light
- optics: science and technology regarding visible light
- passband: range of electromagnetic wavelengths that a filter allows
- phase curve: brightness of an object according to its phase angle
- photochemistry: study of the chemical effects of light
- photoevaporation: dispersal of a gas from UV radiation
- photometer: instrument measuring brightness
- photometric redshift (photo-z): method of estimating redshift without spectroscopy
- photometric system: specification of a set of filters/passbands
- photon counting: sensing EMR down to the photon level
- photon noise: variation in light measurement due to its quantum nature
- Planck function: yields black body curve
- polarimetry: measurement of polarization of EMR
- polarization: property of waves that oscillate in a particular direction
- polarization modes: electric and magnetic aspects of the polarization of electromagnetic radiation
- Poynting vector (S): measures directional energy flux density
- quenched galaxy: galaxy currently producing minimal stars
- R band: band of visible light around 6500 angstroms
- radar: probe based on reflecting radio waves
- radiance: measure of EMR to/from a solid angle through and area
- radiant flux: measure of brightness
- radiation hydrodynamics (RHD): hydrodynamics plus the affects of EMR
- radiation pressure: the pressure exerted by electromagnetic radiation
- radiative flux: power passing through a unit area
- radiative transfer (RT): energy transfer in the form of electromagnetic radiation
- radiative transfer code (RT code): computer model of a gas's radiative transfer
- radiative transfer model (RTM): models of radiative transfer, often computerized
- radio: electromagnetic radiation, frequency 3kHz to 300GHz
- radiometer: device for measuring radiant flux
- Rayleigh-Jeans law: yields approximation of black body curve
- reddening: red appearance of astronomical objects because blue light is attenuated by dust
- redshift (z): change to longer wavelengths due to Doppler affects
- redshift space: concept of space using redshift as the radial dimension
- relativistic beaming: directional relativistic effect on light from relativistic speeds
- relativistic speed: a good fraction of the speed of light
- rest wavelength: normal wavelength observed when not moving in relation to the source
- Schuster-Schwarzschild model: approximation of a star's internal EMR's divergence from isotropic
- sensitivity function (S): function of wavelength giving the sensitivity of an instrument
- solar constant: flux from the Sun at 1 AU
- source function (S): measure indicating the effect of a material on EMR passing through
- spectral energy distribution (SED): function or plot of brightness at each wavelength in the spectrum
- spectral flux density (S): flux or power of radiation per unit area per unit wavelength
- spectral index (α): power by which an object's flux depends on frequency
- spectral line energy distribution (SLED): function or plot of brightness of lines in a spectrum
- spectral resolution: measure of a spectrograph's ability to resolve features of the spectrum
- spectral signature: spectral characteristics indicating the emitting material and conditions
- spectrograph: device to record the spectrum of incoming light
- spectrography: charting the strengths of different electromagnetic wavelengths
- spectrometer: device to measure light by wavelength across its spectrum
- spectrometry: measuring the strengths of different electromagnetic wavelengths
- spectroscope: device to study the spectrum of incoming light
- spectroscopy: measurement of the strengths of different electromagnetic wavelengths
- speed of light (c): fundamental constant measured as the speed at which light travels
- starburst galaxy: galaxy forming stars at a very high rate
- Stokes parameters: way to describe polarization state
- Strömgren photometric system: four-color photometric system devised in 1950s
- submillimeter galaxy (SMG): galaxy that produces significant submillimeter radiation
- subradio: electromagnetic radiation, frequency below 3kHz
- super low frequency (SLF): electromagnetic radiation, frequency 30Hz to 300Hz
- superradiance: Exotic quantum-mechanics light-amplification phenomenon
- surface brightness: brightness per unit area of a surface
- synchrotron radiation: radiation emitted when high-speed charged particles are accelerated
- synchrotron self-Compton (SSC): charged particle cloud scattering its own synchrotron-produced photons
- Thomson optical depth: a measure of affects of Thomson scattering
- transit spectroscopy: spectroscopy through an exoplanet's transit
- transmission spectroscopy: spectrum of radiation passing through a substance
- tremendously low frequency (TLF): electromagnetic radiation, frequency below 3Hz
- two-stream approximation: approximation of a star's internal EMR's divergence from isotropic
- U: photometric filter for ultraviolet light
- UBV photometric system: commonly-cited photometric system for describing stars' colors
- ultra low frequency (ULF): electromagnetic radiation, frequency 300Hz to 3kHz
- ultra-high-energy gamma rays (UHEGR): energetic gamma rays with more than 100 TeV photon energy
- ultraviolet (UV): electromagnetic radiation, wavelength 10-400 nm
- UVOIR: a spectral "band name" covering UV, visible light, and IR
- V: photometric filter for visible light
- Vega system: magnitude calibration such that Vega has zero magnitude
- very low frequency (VLF): electromagnetic radiation, frequency 3kHz to 30kHz
- very-high-energy gamma rays (VHEGR): energetic gamma rays with 100 GeV to 100 TeV photon energy
- very-long-baseline interferometry (VLBI): interferometry based upon storing timing data at each telescope
- visible light: electromagnetic radiation, wavelength 390-750 nm
- wavelength: an alternative description of an electromagnetic wave's frequency or photon energy
- weak lensing: slight lensing detected in random patterns of distant objects
- Wien's displacement law: temperature times wavelength with maximum intensity equals a constant
- X-ray: electromagnetic radiation, wavelength .01 to 10 nanometers
- XEUV: electromagnetic radiation in the range of .15nm-400nm
- Zeeman-Doppler imaging (ZDI): technique for imaging stellar magnetic fields
EMU:
- Australian Square Kilometre Array Pathfinder (ASKAP): radio telescope array of 36 12m dishes
ENA:
- energetic neutral atom (ENA): high-speed neutral atom
Enceladus: Saturn moon considered possible carrier of life
- Enceladus Life Finder (ELF): mission to search for life on Saturn moon Enceladus
- Saturn: second largest planet in the solar system
Enceladus Life Finder (ELF): mission to search for life on Saturn moon Enceladus
endothermic reaction: reaction that absorbs heat
energetic neutral atom (ENA): high-speed neutral atom
energy:
- erg: CGS unit of energy
- foe: unit of energy on the order of a supernova's output
- insolation: solar energy received per unit area in given time
- joule: SI unit of energy
- kinetic energy (KE): an object's energy due to its motion
- potential energy (PE): an object's energy that can be released
- radiative forcing (RF): difference between a planet's incoming and outgoing radiation
- relativistic energy: energy of an object including relativistic effects
- watt (W): SI unit of power
energy density: energy per unit volume
energy spectral density:
- magnetic energy spectrum: spatial spectral density of the energy associated with magnetic fields
- spectral density: strength of power or energy as a function of frequency
engineering:
- signal-to-noise ratio (SNR,S/N): ratio of the power of a signal to the power of the background noise
England:
- COAST: optical interferometer in England
- Cosmic Anisotropy Telescope (CAT): 1990s interferometer to measure CMB variations
- Mark II (MKII): 38m radio telescope in England
entropic gravity:
- modified Newtonian dynamics (MOND): alternative theory of gravity addressing "dark matter"
entropy (S): relative measure of the amount of usable energy available
- modified Newtonian dynamics (MOND): alternative theory of gravity addressing "dark matter"
envelope:
- atmosphere: gas surrounding astronomical object
- post-common envelope binary (PCEB): binary star system showing unusual stellar evolution
Enzo: hydrodynamic simulation system
eon:
- gigayear (Gy,Gyr): a billion years
EOR:
- dark age: interval when the universe's hydrogen atoms were neutral
- epoch of reionization (EOR): time when the universe's neutral hydrogen atoms ionized
- Tomographic Ionized-carbon Mapping Experiment (TIME): proposed instrument to map the [CII] line
EoR-Spec:
- CCAT-prime (CCAT-p): planned 6 meter submillimeter telescope in Chile
EoS:
- asteroid family: set of asteroids based on similar orbits
- equation of state (EoS): equation relating temperature, pressure, and volume
EPAM:
- Advanced Composition Explorer (ACE): satellite collecting solar wind and cosmic rays
ephemeris: information on the position of a celestial body in the sky over time
ephemeris time:
- time standard: method of designating points in time and quantifying time periods
EPIC:
- K2: second Kepler mission that worked around failed equipment
- Subaru XMM-Newton Deep Survey (SXDS): survey using the Subaru telescope and XMM-Newton
- XMM-Newton: X-ray observatory-satellite operated by ESA
EPICS:
- European Extremely Large Telescope (E-ELT,ELT): 39-meter telescope under construction
epicycle: small circular motion around a large circular motion
epicyclic frequency: frequency of oscillation in an accretion disk
- epicycle: small circular motion around a large circular motion
- spiral galaxy: flat galaxy with spiraling arms
EPOCh:
- epoch: time on which to base celestial coordinates
- EPOXI: mission using Deep Impact for further exploration
epoch B1950.0: midnight 1/1/1950 GMT as used as a time reference
epoch J2000.0: noon 1/1/2000 GMT as used as a time reference
epoch of galaxy assembly:
- epoch of galaxy formation: before z=1, when many galaxies formed
epoch of galaxy formation: before z=1, when many galaxies formed
epoch of reionization (EOR): time when the universe's neutral hydrogen atoms ionized
EPOXI: mission using Deep Impact for further exploration
EPS merger trees:
- semi-analytic model (SAM): cosmological model combining analytic and other methods
Epsilon Eridani: third nearest visible star system in sky
Epsilon Ind A ab:
- Epsilon Indi (ε Indi,ε Ind): nearby star system including two brown dwarf companions
Epsilon Indi (ε Indi,ε Ind): nearby star system including two brown dwarf companions
EPTA:
- European Pulsar Timing Array (EPTA): European collaboration of radio telescopes
EPTA+:
- European Pulsar Timing Array (EPTA): European collaboration of radio telescopes
equant:
- epicycle: small circular motion around a large circular motion
equation:
- Boltzmann equation: equation relating atomic excitation to temperature
- Drake equation: estimate of advanced life in the Milky Way
- equation of radiative transfer (RTE): equation describing energy transfer by EMR
- Fokker-Planck equation: shows likelihood of velocity over time of a disturbed particle
- general relativity (GR): formula relating gravity, space, time, and mass
- Lane-Emden equation: form of equation of state for gas ball in hydrostatic equilibrium
- mass-luminosity relation: model relating stellar mass and luminosity
- Maxwell's equations: four equations describing electricity and magnetism
- Saha equation: equation relating ionization to temperature
- telegrapher's equations: two equations describing a transmission line
- Tillotson equation: equation of state for high speed impacts
equation of radiative transfer (RTE): equation describing energy transfer by EMR
equation of state (EoS): equation relating temperature, pressure, and volume
- Tillotson equation: equation of state for high speed impacts
Equation of State: Supernovae Trace Cosmic Expansion:
- ESSENCE: survey using supernova data to study dark energy
equatorial:
- celestial coordinate system: system for specifying position of celestial objects
- declination (dec): direction coordinate above/below celestial equator
- epoch: time on which to base celestial coordinates
- equatorial coordinate system: latitude/longitude-like system for the celestial sphere
- equinox: times when tilt of Earth is neither toward or away from the Sun
- International Celestial Reference System (ICRS): standardized variation of equatorial coordinate system
- right ascension (RA): direction coordinate along celestial equator
equatorial coordinate system: latitude/longitude-like system for the celestial sphere
equatorial coordinates:
- equatorial coordinate system: latitude/longitude-like system for the celestial sphere
equatorial Kelvin wave:
- Kelvin waves: pressure and gravity waves formed by Coriolis force and a barrier
equatorial mount: telescope mount with axis parallel to Earth's
equatorial Rossby wave:
- Kelvin waves: pressure and gravity waves formed by Coriolis force and a barrier
equatorial wave:
- Kelvin waves: pressure and gravity waves formed by Coriolis force and a barrier
equilibrium condensation model: chemical model explaining solar system planet abundances
equilibrium temperature (T_eq,Teq): temperature a planet would have if it were an externally-heated black body
equinox: times when tilt of Earth is neither toward or away from the Sun
equipment:
- drogue chute: parachute to slow something moving at high speed
- filter: optical device to filter out part of the EMR spectrum
- mirror support cell: units in a telescope that support the mirror
- MMRTG: power source for space probes
- Space Launch System (SLS): launch rocket in development, e.g., for future astronomical projects
equivalent width:
- line broadening: processes causing a spectral line to have width
era of reionization:
- epoch of reionization (EOR): time when the universe's neutral hydrogen atoms ionized
erg: CGS unit of energy
ergosphere: type of region of space around rotating black hole
- black hole (BH): region of such high mass that light cannot escape
Eridanus Supervoid:
- void: empty spaces between large scale structures
Eridanus Void:
- Sculptor Wall: large slab of galaxies
Eris:
- dwarf planet: round like a planet, only smaller
- Kuiper Belt (K Belt,KB): further part of solar system beyond Neptune
- plutoid: Pluto-like dwarf planet
ERNE:
- Solar and Heliospheric Observatory (SOHO): satellite observing the Sun
EROS: search for MACHOs
EROS-1:
- EROS: search for MACHOs
EROS-2:
- EROS: search for MACHOs
erosion:
- ablation: erosion of the surface of an object
- weathering: changes in surface due to contact with atmosphere
erosion barrier:
- planet formation: process by which planets form
eROSITA: future space X-ray telescope
error bar: feature of a graph to indicate accuracy
ESA:
- ARIEL: planned space mission for exoplanet spectrography
- BepiColombo: mission to Mercury
- Cassini: explorer spaceship sent to Saturn
- CHEOPS: space telescope in development to measure radii of exoplanets
- COROT: observatory-satellite to look for transiting exoplanets and stellar oscillations
- Darwin: past plan for space telescopes acting as an interferometer
- Euclid: planned observatory-satellite to measure dark energy
- European Space Agency (ESA): NASA-like international space organization in Europe
- EXOSAT: 1980s European space X-ray telescope
- Gaia: survey satellite at 400-1000 nanometers
- Herschel Space Observatory: infrared observatory-satellite with 3.5 meter reflector
- Hipparcos: ESA astrometry space observatory circa 1990
- Infrared Space Observatory (ISO): 1990s 60cm infrared space telescope
- INTEGRAL: European gamma ray observatory-satellite
- International Ultraviolet Explorer (IUE): 1980s ultraviolet space telescope
- James Webb Space Telescope (JWST): future space-based 6.5 meter infrared telescope
- JUICE: mission to Jupiter in development
- LISA: proposed space mission to detect gravitational waves
- Mars Express: Mars probe launched by ESA in 2003
- New Gravitational Wave Observatory (NGO): proposed space mission to detect gravitational waves
- Planck: microwave telescope in space
- PLATO: planned observatory-satellite aimed at finding exoplanets
- Rosetta: space probe that visited a comet
- Solar and Heliospheric Observatory (SOHO): satellite observing the Sun
- THEMIS: set of satellites studying the Earth's magnetic field
- XMM-Newton: X-ray observatory-satellite operated by ESA
escape fraction: fraction of ionizing photons escaping a body
escape velocity (V_e): minimal velocity that allows something to overcome a body's gravity
- atmosphere: gas surrounding astronomical object
- hydrodynamic escape: ongoing escape of gas particles from atmosphere
- Jeans escape: ongoing escape of gas particles from atmosphere
ESD:
- spectral density: strength of power or energy as a function of frequency
ESO:
- Astronet: European astronomy consortium
- Atacama Large Millimeter Array (ALMA): large radio telescope array in Chile
- Cherenkov Telescope Array (CTA): ground gamma-ray telescope array in development
- ESO/Uppsala Survey of the ESO (B) Atlas: 1970s southern all-sky survey
- European Extremely Large Telescope (E-ELT,ELT): 39-meter telescope under construction
- European Southern Observatory (ESO): organization operating telescopes in the southern hemisphere
- European Southern Observatory Very Large Telescope (ESO VLT,VLT): four 8.2-meter optical telescopes in Chile that can act together
- Giant Metrewave Radio Telescope (GMRT): large radio interferometer in India
- Hamburg/ESO Survey (HE): 1990s southern hemisphere survey aimed at finding quasars
- New Technology Telescope (NTT): 3.58 meter reflecting telescope in Chile
- Overwhelmingly Large Telescope (OWL): 100m telescope plan
- PESSTO: survey for transients carried out on the NTT
- SPECULOOS: search for Earth-like exoplanets orbiting nearby dim stars
- UK Schmidt Survey: photographic survey of the southern hemisphere sky
- VLT Survey Telescope (VST): survey telescope located at the VLT site
ESO (B) Atlas:
- ESO/Uppsala Survey of the ESO (B) Atlas: 1970s southern all-sky survey
ESO 137-001: barred spiral galaxy in the Abell 3627 cluster
ESO 3.6 Meter Telescope:
- HARPS: high-precision spectrograph for exoplanet searches
ESO 97-G13:
- Circinus Galaxy (ESO 97-G13): nearest Seyfert galaxy
ESO Quick Blue Survey:
- ESO/Uppsala Survey of the ESO (B) Atlas: 1970s southern all-sky survey
ESO Schmidt Camera:
- Hamburg/ESO Survey (HE): 1990s southern hemisphere survey aimed at finding quasars
ESO Schmidt Telescope:
- DENIS: 1990s southern sky survey of two near-infrared bands
- ESO/Uppsala Survey of the ESO (B) Atlas: 1970s southern all-sky survey
- QUEST: sixteen square-degree survey camera
- SuperCOSMOS Sky Survey (SSS): survey of stars and galaxies from legacy plates
ESO VLT:
- Atacama Desert: high altitude, dry plateau in Chile, the site of observatories
- European Southern Observatory Very Large Telescope (ESO VLT,VLT): four 8.2-meter optical telescopes in Chile that can act together
- Multi-object Optical and Near-IR Spectrograph (MOONS): advanced spectrograph under development for VLT
ESO/SERC Southern Sky Atlas:
- UK Schmidt Survey: photographic survey of the southern hemisphere sky
ESO/SERC Survey:
- UK Schmidt Survey: photographic survey of the southern hemisphere sky
ESO/Uppsala Survey of the ESO (B) Atlas: 1970s southern all-sky survey
ESO594-G004:
- Sagittarius Dwarf Irregular Galaxy (SagDIG): most distant galaxy in the Local Group
ESPaDOnS:
- Canada-France-Hawaii Telescope (CFHT): 3.6 meter optical/infrared telescope in Hawaii
- Zeeman-Doppler imaging (ZDI): technique for imaging stellar magnetic fields
ESPRESSO:
- European Southern Observatory Very Large Telescope (ESO VLT,VLT): four 8.2-meter optical telescopes in Chile that can act together
ESSENCE: survey using supernova data to study dark energy
Eta Carinae:
- hypergiant: extremely bright stars
ETG:
- galaxy: gravitationally-bound group of stars
ethane:
- hydrocarbon (HC): any compound of just carbon and hydrogen
ethene:
- ethylene (C₂H₄): compound of two carbon and four hydrogen atoms
ether:
- relativity: physics models accommodating the constancy of the speed of light
ethylene (C₂H₄): compound of two carbon and four hydrogen atoms
ethyne:
- acetylene (C₂H₂): compound of two carbon and two hydrogen atoms
ETNO:
- trans-Neptunian object (TNO): minor planet beyond Neptune
Euclid: planned observatory-satellite to measure dark energy
Eulerian code:
- stellar structure: the presumed internal structure of stars
Eunomia:
- asteroid family: set of asteroids based on similar orbits
Europa: well-known Jupiter moon
- Europa Clipper: planned Europa space probe
Europa Clipper: planned Europa space probe
Europa Multiple Flyby Mission:
- Europa Clipper: planned Europa space probe
Europe:
- European Pulsar Timing Array (EPTA): European collaboration of radio telescopes
- European Southern Observatory (ESO): organization operating telescopes in the southern hemisphere
- European Space Agency (ESA): NASA-like international space organization in Europe
- Institut de radioastronomie millimétrique (IRAM): organized radio astronomy collaboration between France, Germany, and Spain
- Low-frequency Array (LOFAR): low frequency radio telescope
European:
- Astronet: European astronomy consortium
- European Extremely Large Telescope (E-ELT,ELT): 39-meter telescope under construction
- European Southern Observatory Very Large Telescope (ESO VLT,VLT): four 8.2-meter optical telescopes in Chile that can act together
- European VLBI Network (EVN): consortium of radio telescopes to coordinate VLBI efforts
- EXOSAT: 1980s European space X-ray telescope
- INTEGRAL: European gamma ray observatory-satellite
- VLT Survey Telescope (VST): survey telescope located at the VLT site
- XMM-Newton: X-ray observatory-satellite operated by ESA
European Extremely Large Telescope (E-ELT,ELT): 39-meter telescope under construction
European Gravitational Observatory (EGO): gravitational wave observatory in Italy
European Large Area ISO Survey:
- Infrared Space Observatory (ISO): 1990s 60cm infrared space telescope
European Pulsar Timing Array (EPTA): European collaboration of radio telescopes
European Southern Observatory (ESO): organization operating telescopes in the southern hemisphere
European Southern Observatory Very Large Telescope (ESO VLT,VLT): four 8.2-meter optical telescopes in Chile that can act together
- Multi-object Optical and Near-IR Spectrograph (MOONS): advanced spectrograph under development for VLT
European Space Agency (ESA): NASA-like international space organization in Europe
European VLBI Network (EVN): consortium of radio telescopes to coordinate VLBI efforts
European X-ray Observatory Satellite:
- EXOSAT: 1980s European space X-ray telescope
europium:
- Ap star: peculiar type of A star
EUV:
- extreme ultraviolet (EUV,XUV): electromagnetic radiation in the range of 10nm-124nm
EUVE:
- Extreme Ultraviolet Explorer (EUVE): 1990s ultraviolet space telescope
evaluation:
- mock catalog: catalog of simulated astronomical bodies
evaporation: particles escaping, e.g., liquid molecules escaping as gas
EVE:
- Solar Dynamics Observatory (SDO): 2010 satellite observing the Sun
event:
- 1947 sunspot: largest sunspot ever recorded
- 775 AD event: apparent solar eruption, based upon tree-ring evidence
- Big Bang: theoretical event when the universe expanded from a point
- Carrington event: solar storm September 1-3 1859
- Cassiopeia A: supernova remnant visible for 300 years
- epoch of reionization (EOR): time when the universe's neutral hydrogen atoms ionized
- great debate: historical debate regarding the nature of galaxies
- GW170817: gravitational wave detection from a neutron star merger
- late heavy bombardment (LHB): time after solar system planet-formation when many impacts occurred
- recombination: time when the universe's ionized hydrogen atoms neutralized
- SN 1987A (1987A): supernova in February 1987 rare for being visible by the naked eye
- SN 2014J: type Ia supernova in Messier 82, the Cigar Galaxy
event horizon (EH): surface-shape around a black hole through which light cannot escape
- black hole (BH): region of such high mass that light cannot escape
- ergosphere: type of region of space around rotating black hole
- law of cosmic censorship: a singularity cannot be observed
Event Horizon Telescope (EHT): growing VLBI network
event type:
- black hole merger: two black holes meeting and forming one
- calcium-rich gap transient: type of explosive event larger than a nova and smaller than a supernova
- core collapse supernova: supernova resulting from the collapse of the core of a star
- coronal mass ejection (CME): mass of plasma ejected from the Sun
- dwarf nova: flash of a cataclysmic variable star
- equinox: times when tilt of Earth is neither toward or away from the Sun
- fast radio burst (FRB): astronomical high energy radio pulses of a few milliseconds
- gamma-ray burst (GRB): short flashes of gamma rays apparently from outside our galaxy
- geomagnetic storm: disturbance in Earth's magnetosphere
- helium flash: helium ignition in a star
- helium runaway shell: helium ignition in a shell in AGB giants
- kilonova: explosive event larger than a nova and smaller than a supernova
- magnetic reconnection: change in magnetic topology within a fluid
- neutron star merger: two neutron stars meeting and forming one
- nova: white dwarf explosion
- occultation: one celestial body hiding another from an observer
- secondary eclipse: eclipse of a body that also transits
- solar eruption: sudden brightening of the Sun
- solar flare: sudden brightening of the Sun
- solar storm: general term for events on the Sun
- solstice: moment when Sun reaches its northern- or southern-most position
- stellar encounter: stars passing close to each other
- superluminous supernova (SLSN): stellar explosion larger than a supernova
- supernova (SN): stellar explosion larger than a nova
- thermal pulse: pulse in an AGB star due to helium fusion in a shell
- tidal disruption event (TDE,TDF): star pulled apart by black hole tidal forces
- transit: a celestial body passing between another and an observer
- Type Ia supernova: type of supernova for which distance can be determined
EVN:
- European VLBI Network (EVN): consortium of radio telescopes to coordinate VLBI efforts
Evolution and Assembly of Galaxies and their Environments:
- EAGLE: simulation of galaxy formation and evolution
Evolutionary Map of the Universe:
- Australian Square Kilometre Array Pathfinder (ASKAP): radio telescope array of 36 12m dishes
evolutionary track: H-R diagram track of the life of a star
exaFLOP:
- exascale computing: exaFLOP computing capability, i.e., quintillion FLOPs
ExAO:
- extreme adaptive optics (ExAO): high-performance version of AO system
exascale computing: exaFLOP computing capability, i.e., quintillion FLOPs
excitation:
- atomic excitation: atoms with electrons above the ground state
excitation temperature:
- temperature: measure of heat in matter
excited state:
- atomic excitation: atoms with electrons above the ground state
exit pupil: size of the image as presented to the eye
EXO:
- EXOSAT: 1980s European space X-ray telescope
Exo-C:
- Exo-S: a study on the concept of a starshade mission
exo-Earth:
- exoearth: Earth-like exoplanet
Exo-S: a study on the concept of a starshade mission
Exo-starshade:
- Exo-S: a study on the concept of a starshade mission
exobase:
- exosphere: outer portion of atmosphere
ExoCTK: collection of software for exoplanet observation and analysis
exoearth: Earth-like exoplanet
ExoFOP: site to facilitate exoplanet follow-up observation
ExoFOP-Kepler:
- ExoFOP: site to facilitate exoplanet follow-up observation
ExoFOP-TESS:
- ExoFOP: site to facilitate exoplanet follow-up observation
ExoMars:
- Mars: well-explored planet in the solar system
exomoon:
- exosatellite: natural satellite not in the solar system
- Kepler-1625b: giant exoplanet in a star's habitable zone
exoplanet:
- 51 Eridani b: Jupiter-like planet discovered in 2015
- 51 Pegasi b (51 Peg b): first exoplanet found orbiting a main sequence star
- 55 Cancri e (55 Cnc e): superearth orbiting a Sun-like star
- Beta Pictoris b (β Pic b): super Jupiter discovered in 2008
- extra-solar planet: planet not in the solar system
- GJ 1132 b: Earth-like extrasolar planet discovered in 2015
- GJ 1214 b: super-Earth extrasolar planet discovered in 2009
- HD 209458 b: hot Jupiter discovered in 1999
- HD 80606 b: hot Jupiter discovered in 2001
- Kepler-1625b: giant exoplanet in a star's habitable zone
- Kepler-186f: Earth-like exoplanet in a star's habitable zone
- Proxima b: exoplanet orbiting Proxima Centauri
- WASP-67b: hot Jupiter discovered in 2011
Exoplanet Characterization Toolkit:
- ExoCTK: collection of software for exoplanet observation and analysis
exoplanet demographics:
- demographics: statistics of characteristics within a group
exoplanet eclipse light curve: graph of light as an exoplanet transits in front of its star
Exoplanet Follow-up Observing Program:
- ExoFOP: site to facilitate exoplanet follow-up observation
Exoplanet Starshade:
- Exo-S: a study on the concept of a starshade mission
- starshade: spacecraft to block light from a specific body
exoplanets:
- Alpha Centauri: nearest star system
- ARIEL: planned space mission for exoplanet spectrography
- astrobiology: study of extra-terrestrial life
- atmospheric model: model to describe or simulate a planet's atmosphere
- AU Microscopii (AU Mic): nearby star with disk and planets
- Automated Planet Finder (APF): robotic telescope to find exoplanets using RV method
- carbon planet: theoretical planet type with more carbon than oxygen
- Carl Sagan Institute (CSI): group researching finding life on other planets and moons
- CHEOPS: space telescope in development to measure radii of exoplanets
- COROT: observatory-satellite to look for transiting exoplanets and stellar oscillations
- Darwin: past plan for space telescopes acting as an interferometer
- direct imaging: detection/observation of exoplanets by taking pictures of it
- double transit: star showing transits of two bodies
- Drake equation: estimate of advanced life in the Milky Way
- eclipse mapping: using eclipse light curves to map surface features
- EPOXI: mission using Deep Impact for further exploration
- equilibrium temperature (T_eq,Teq): temperature a planet would have if it were an externally-heated black body
- ExoCTK: collection of software for exoplanet observation and analysis
- exoearth: Earth-like exoplanet
- ExoFOP: site to facilitate exoplanet follow-up observation
- exoplanet eclipse light curve: graph of light as an exoplanet transits in front of its star
- FINESSE: planned space mission for exoplanet spectrography
- Fulton gap: planets with radius 1.5 to 2 Earth radii are rare
- gas giant: large planet made largely of gas
- gas planet: planet made largely of gas
- Gemini Planet Imager (GPI): infrared instrument to overcome signal noise imaging exoplanets
- giant planet: planet of more than 10 Earth masses
- greenhouse effect: mechanism that boosts temperature through selective blocking of EMR
- HabEx: proposed space mission to directly image exoplanets
- habitability: ability of a planet to support life
- habitable zone (HZ): zone where conditions are favorable for life
- HARPS: high-precision spectrograph for exoplanet searches
- HARPS-N: high-precision spectrograph for exoplanet searches in Canary Islands
- HATNet: distributed array of telescopes to search for transients
- HCI: imaging of targets very near bright objects
- HD 133131: binary star system with exoplanets
- hot Jupiter (HJ): Jupiter-sized gas exoplanet orbiting very close to star
- HR 8799: star with four exoplanets
- ice giant: planet more massive than gas planets and less than rocky planets
- inflated radii: exceptionally large radii of some hot Jupiters
- K2: second Kepler mission that worked around failed equipment
- Keck Planet Finder (KPF): spectrograph in development for Keck
- Keck Planet Imager and Characterizer (KPIC): proposed noise-reducing planet imager for Keck
- Kepler Telescope: space telescope that watched stars for exoplanets
- LHS 1140: red dwarf with rocky planet in its habitable zone
- Lupus Transit Survey: survey for hot Jupiters in a region of constellation Lupus
- magma ocean: presumed to occur early in Earth history and potentially on exoplanets
- MASCARA: distributed array of telescopes to search for exoplanets
- maximum iron fraction: derived from planet-formation models
- MEarth Project (MEarth): automated observatories monitoring nearby red dwarfs for transits
- mega-Earth: rocky planet ten times the size of Earth
- minimum mass (m sin i): measured bound on the mass of an exoplanet
- MOA: search for microlensing
- New Worlds Mission: plan for space occulter to facilitate the view of exoplanets
- Nice model: model of the evolution of the solar system
- Other Worlds Laboratory (OWL): group researching planets and moons
- PALMS: survey to find exoplanets for direct imaging
- Palomar Transient Factory (PTF): survey designed to find transients
- PanCET: HST UV/optical/NIR survey of selected exoplanets
- phase curve: brightness of an object according to its phase angle
- Planet Hunters (PH): crowdsourcing website to identify galaxy types from surveys
- planet type: methods of classifying planets
- PLATO: planned observatory-satellite aimed at finding exoplanets
- Pre-OmegaTranS (POTS): transit search using MPG/ESO Telescope
- PSR 1957+12: pulsar with first discovered planet system
- Qatar Exoplanet Survey (QES): photometric survey in search of transients
- retrograde hot Jupiter: large hot planet orbiting opposite the expected direction
- rocky planet: planet like Earth and Mars, mostly rock
- Rossiter-McLaughlin effect (RM effect,RM): effect of transit on visible spectrum of the star
- Sagittarius Window Eclipsing Extrasolar Planet Search (SWEEPS): transit search using HST time
- secondary eclipse: eclipse of a body that also transits
- SPECULOOS: search for Earth-like exoplanets orbiting nearby dim stars
- SPHERE: VLT instrument for imaging exoplanets
- starshade: spacecraft to block light from a specific body
- super-Earth: exoplanet more massive than Earth but substantially less than Neptune
- SuperWASP (SWASP): broad Earth-based search for transiting planets
- Terrestrial Planet Finder (TPF): plan for space telescopes to find smaller exoplanets
- transit spectroscopy: spectroscopy through an exoplanet's transit
- transit timing variations (TTV): variations in the timing of the transits of exoplanets and binaries
- Transiting Exoplanet Survey Satellite (TESS): observatory-satellite searching for transiting exoplanets
- transiting planet: planet crossing between another body and the observer
- TRAPPIST-1: red dwarf with exoplanet near the habitable zone
- Ultimate Spitzer Phase Curve Survey (USPCS): investigation of exoplanet atmospheres
- WASP: multi-university initiative to locate transiting planets
- water-ice planet: planet made entirely of water ice
- WFCAM Transit Survey (WTS): 2000s survey for exoplanet transits using UKIRT
EXOSAT: 1980s European space X-ray telescope
exosatellite: natural satellite not in the solar system
exosphere: outer portion of atmosphere
- ionosphere: layers of Earth atmosphere with significant ions
exothermic reaction:
- endothermic reaction: reaction that absorbs heat
Expérience pour la Recherche d'Objets Sombres:
- EROS: search for MACHOs
expansion fan: the "sound" of a supersonic flow flowing around a convex corner
experiment:
- gravity sounding: measuring a planet's gravitation field by study of nearby probe flights
Explorer 42:
- Uhuru: 1970 satellite X-ray telescope
Explorer 80:
- Wilkinson Microwave Anisotropy Probe (WMAP): spacecraft that measured variations in the cosmic background radiation
Explorers Program:
- Extreme Ultraviolet Explorer (EUVE): 1990s ultraviolet space telescope
- Far Ultraviolet Spectroscopic Explorer (FUSE): early 2000s space telescope for short-wavelength ultraviolet
- NASA: includes space-based astronomy research
exposure time:
- survey depth: indication of how far a survey reaches
Extended Baryon Oscillation Spectroscopic Survey:
- Baryon Oscillation Spectroscopic Survey (BOSS): survey of spatial distribution of luminous red galaxies and quasars
Extended BOSS:
- Baryon Oscillation Spectroscopic Survey (BOSS): survey of spatial distribution of luminous red galaxies and quasars
Extended Chandra Deep Field-South Survey (ECDFS): 1100 square arcminute X-ray survey
Extended Groth Strip (EGS): region of sky searched for distant galaxies
Extended Roentgen Survey with an Imaging Telescope Array:
- eROSITA: future space X-ray telescope
extinction: the absence of any radiation from an astronomical object because all is absorbed or scattered
extinction coefficient:
- extinction: the absence of any radiation from an astronomical object because all is absorbed or scattered
extinction curve:
- extinction: the absence of any radiation from an astronomical object because all is absorbed or scattered
extinction event:
- mass extinction: event in which many species went extinct
extra-solar planet: planet not in the solar system
extragalactic background light (EBL): electromagnetic radiation from star formation and AGNs
extragalactic distance scale:
- cosmic distance ladder: sequence of methods of measuring distance to astronomical objects
extrasolar moon:
- exosatellite: natural satellite not in the solar system
Extrasolar Planet Observation and Characterization:
- EPOXI: mission using Deep Impact for further exploration
Extrasolar Planet Observation and Deep Impact Extended Investigation:
- EPOXI: mission using Deep Impact for further exploration
extrasolar satellite:
- exosatellite: natural satellite not in the solar system
extreme adaptive optics (ExAO): high-performance version of AO system
extreme emission line galaxy:
- emission line galaxy (ELG): a galaxy type characterized by emission lines
extreme energy cosmic rays:
- cosmic rays (CR): very-high-energy particles from beyond the solar system
extreme Kuiper Belt object:
- Kuiper Belt (K Belt,KB): further part of solar system beyond Neptune
extreme luminous supergiant:
- luminosity class: classification of size/luminosity of stars
- supergiant: very large giant star
extreme trans-Neptune object:
- trans-Neptunian object (TNO): minor planet beyond Neptune
extreme trans-Neptunian object:
- trans-Neptunian object (TNO): minor planet beyond Neptune
extreme ultraviolet (EUV,XUV): electromagnetic radiation in the range of 10nm-124nm
- Extreme Ultraviolet Explorer (EUVE): 1990s ultraviolet space telescope
Extreme Ultraviolet Explorer (EUVE): 1990s ultraviolet space telescope
extreme-energy cosmic rays:
- GZK limit: limit on energy of cosmic rays
Extremely Large Telescope:
- European Extremely Large Telescope (E-ELT,ELT): 39-meter telescope under construction
- extremely large telescope (ELT): optical telescope with a 20+ meter aperture
extremely low frequency (ELF): electromagnetic radiation, frequency 3Hz to 30Hz
extremely luminous infrared galaxy:
- luminous infrared galaxy (LIRG): a galaxy emitting a lot of far-infrared light
extrinsic S-star:
- S-type star: type of star with lines indicating zirconium
eye piece:
- exit pupil: size of the image as presented to the eye
eye relief:
- exit pupil: size of the image as presented to the eye

index