Term Index (P)
- P Cygni:
- P Cygni profile: line profile showing both red and blue shifts
- P orbital:
- P-Cam:
- CCAT-prime (CCAT-p): planned 6 meter submillimeter telescope in Chile
- P-CMBcam:
- CCAT-prime (CCAT-p): planned 6 meter submillimeter telescope in Chile
- P-curve:
- PCA analysis: an automatable method of determining galaxy morphology
- p-mode:
- P-P chain:
- P-P space:
- P-P-P space:
- P-P-V space:
- P-Pdot diagram: diagram comparing the rotation and the slowing of pulsars
- P-Spec:
- CCAT-prime (CCAT-p): planned 6 meter submillimeter telescope in Chile
- P-V:
- wavefront error (WFE): measure of a telescope's distortion of incoming waves
- P-V space:
- P48:
- P60:
- P7:
- P500:
- PA:
- PACS:
- PACS Evolutionary Probe:
- PEP: survey aimed at early star formation
- PAH:
- PAH emissions: infrared emission from polycyclic aromatic hydrocarbons in gas clouds
- pair instability:
- pair production: creation of a particle/antiparticle pair
- pair-instability supernova:
- PAIRITEL:
- Pal:
- paleomagnetism: ancient magnetic fields and their characteristics
- Pallas:
- asteroid: minor planet without comet characteristics
- protoplanet: simplest, least-developed object classified as a planet
- PALM-3000:
- PALMS: survey to find exoplanets for direct imaging
- Palomar:
- Palomar 48:
- Palomar 48 Inch Telescope (P48): 48 inch Schmidt telescope at Palomar Observatory
- Palomar 48-inch Schmidt:
- Palomar 60 Inch Telescope (P60): 60 inch telescope at Palomar Observatory
- Palomar Digital Sky Survey:
- Palomar Four-filter Survey (PC): Hale telescope survey aimed at discovering high-redshift quasars
- Palomar Globular Clusters (Pal): list of 15 globular clusters found in POSS plates
- Palomar Maps:
- Palomar Observatory:
- Palomar Observatory Sky Survey (POSS): 1950s photographic plates from Palomar 48 inch telescope
- Palomar Observatory Sky Survey I:
- Palomar Observatory Sky Survey II:
- Palomar Proper Motion Survey:
- Palomar Testbed Interferometer (PTI): near-infrared interferometer experiment
- Palomar Transient Factory (PTF): survey designed to find transients
- Palomar-Green Catalog:
- Palomar-Green Survey (PG): list of quasars with excess ultraviolet light
- Palomar-Quest Sky Survey:
- Palomar-Quest Survey:
- Pan:
- Pan-Andromeda Archaeological Survey:
- Pan-STARRS: set of survey telescopes
- Pan-STARRS 1:
- Pan-STARRS Object:
- Pan-STARRS1:
- Pancam:
- PanCET: HST UV/optical/NIR survey of selected exoplanets
- panchromatic: involving all colors, i.e., all wavelengths
- Panchromatic Comparative Exoplanet Treasury:
- PanCET: HST UV/optical/NIR survey of selected exoplanets
- PAndAS: survey of M31 and M33
- Pandora:
- Panoramic Survey Telescope and Rapid Response System:
- PAPER: radio interferometer for 21cm measurement
- Par:
- parabola:
- paradigm:
- relativity: physics models accommodating the constancy of the speed of light
- parallax: angle due to different lines of sight
- parallax angle:
- parallax: angle due to different lines of sight
- Paranal Observatory:
- parent nuclide:
- Parkes 210ft Telescope:
- Parkes 64m Telescope:
- Parkes Catalog (PKS): catalog of from 1960s-1990 of radio sources in southern hemisphere
- Parkes HI Zone of Avoidance Shallow Survey:
- Parkes HI Zone of Avoidance Survey (HIZOA): radio survey to identify galaxies hidden by the zone of avoidance
- Parkes Observatory: Australian large single-dish radio telescope
- Parkes Pulsar Timing Array (PPTA): group of pulsars timed by Parkes Observatory
- Parkes-MIT-NRAO Surveys (PMN): 1990 southern-hemisphere radio surveys
- Parsamian:
- Parsamian Nebula Catalog: 1965 list of nebulae
- parsec (pc): about 3.26 light-years
- light-year (ly): distance that light travels in a year
- partial derivative:
- partial differential equation (PDE): equation constructed as if the variables differentiated are independent
- partial ionization zone: portion of some stars where gas is partially ionized
- partial pressure:
- partial vapor pressure:
- partially ionized:
- particle: very small thing
- alpha particle: essentially a helium nucleus stemming from radioactivity
- axion (A0): proposed light, electrically neutral elementary particle
- baryon: protons, neutrons, and other three-quark particles
- cosmic dust: cosmic dust is dust in space such as interstellar dust
- neutralino: proposed type of particle that might include wimps
- neutrino (ν): light, electrically neutral elementary particle
- pion (π): first type of meson discovered
- WIMP: proposed particle comprising dark matter
- particle horizon: furthest point from which light can reach us
- particle mixing:
- quantum mixing: means by which one particle spontaneously changes to another
- particle spectrometer: device to determine the characteristics of incoming particles
- particle-antiparticle annihilation:
- antimatter: similar to normal matter but with opposite electrical charge
- particles:
- partition function (Z): scale factor for Boltzmann factors
- partitioning:
- Partiview: visualization software aimed at 4d data
- Pascal:
- Paschen:
- Paschen series: hydrogen lines for electrons settling from n > 3 to n = 3
- Paschen series: hydrogen lines for electrons settling from n > 3 to n = 3
- PASJ:
- passband: range of electromagnetic wavelengths that a filter allows
- passband filter:
- filter: optical device to filter out part of the EMR spectrum
- passive dust: dust in a model that is influenced but does not influence
- past:
- patterned ground:
- Paul Wild Observatory:
- Pauli exclusion principle: fermions in a quantum system cannot have identical quantum numbers
- Pavo-Indus Supercluster:
- PAWS: survey of GMCs in M51a
- PC:
- PCA:
- PCA analysis: an automatable method of determining galaxy morphology
- RXTE: space mission to time X-ray variations
- PCA analysis: an automatable method of determining galaxy morphology
- PCEB:
- PdBI:
- PdBI Arcsecond Whirlpool Survey:
- PAWS: survey of GMCs in M51a
- PDE:
- PDF:
- PDR:
- PDS:
- PDS 456:
- pE:
- peak epoch:
- peak epoch of star formation:
- peak star-formation epoch: around 10 billion years ago when star formation peaked
- peak star-formation era:
- peak-to-valley wavefront error:
- wavefront error (WFE): measure of a telescope's distortion of incoming waves
- pebble:
- cosmic dust: cosmic dust is dust in space such as interstellar dust
- pebble accretion: accretion of pebble-sized solids to a planetary embryo
- accretion: enlargement of an astronomical body by gravitationally attracting additional mass
- planet formation: process by which planets form
- peculiar motion:
- peculiar velocity: velocity with respect to local rest
- peculiar velocity diagram:
- Penrose Process:
- PEP: survey aimed at early star formation
- JUICE: mission to Jupiter in development
- PEPSI:
- PEPSSI:
- periapse:
- apsis: closest or furthest point in an eccentric orbit
- periapsis:
- apsis: closest or furthest point in an eccentric orbit
- eccentricity (e): degree to which an orbit is non-circular
- mean anomaly: angle describing an object's position within an elliptical orbit
- pericenter:
- apsis: closest or furthest point in an eccentric orbit
- perigalacticon:
- apsis: closest or furthest point in an eccentric orbit
- perigee:
- apsis: closest or furthest point in an eccentric orbit
- perihelion:
- period:
- period-luminosity relation:
- period-luminosity-color relation:
- period-mean density relation:
- Perkins Telescope:
- Mimir: multi-function near-infrared instrument on Perkins Telescope
- permafrost:
- Mars: well-explored planet in the solar system
- polygonal ground: crack pattern in ground forming polygons due to freezing
- permeability (κ,k): ability of a material to allow fluids to pass through it
- Perseus Arm:
- spiral arm: long, winding visible structure within a spiral galaxy
- Perseus Complex:
- Perseus-Pisces Supercluster: nearby supercluster
- perturbation:
- perturbation theory: breaking an equation into a solvable part and approximatable part
- peryton:
- fast radio burst (FRB): astronomical high energy radio pulses of a few milliseconds
- PESSTO: survey for transients carried out on the NTT
- PETIT:
- PFIP:
- PFS:
- Pfund series:
- hydrogen (H): most prominent element, atomic number 1
- PG:
- PGC:
- PGC 10217:
- PGC 63287:
- PGC 9892:
- Council of Giants: twelve large galaxies surrounding the Local Group
- IC 342: spiral galaxy in the Council of Giants
- PH:
- acidity (pH): measure of the activity of hydrogen ions in a solution
- Planet Hunters (PH): crowdsourcing website to identify galaxy types from surveys
- PHARO:
- phase:
- phase angle: view angle of reflected light implied by the phase of the Moon
- phase curve: brightness of an object according to its phase angle
- phase curve: brightness of an object according to its phase angle
- phase integral:
- phase line:
- phase plane:
- phase space: space of all possible states of a system
- phase transition: transformation from one state of matter to another
- phased array: method of using a set of antennas directionally
- phased array feed:
- phased array: method of using a set of antennas directionally
- PHEBUS:
- GRANAT: observatory-satellite for detecting gamma rays and X-rays
- PHIBSS: survey of CO in distant galaxies
- Philae:
- Rosetta: space probe that visited a comet
- Phillips relation:
- Phillips relationship:
- PHO:
- Phobos:
- Mars: well-explored planet in the solar system
- moon: a planet's natural satellite, such as Earth's
- PHOENIX:
- PHOENIX code:
- PHOENIX stellar model: computer model of a stellar photosphere
- phone number: colloquial expression for coordinates
- phosphorus:
- photino:
- photo-z:
- photochemistry: study of the chemical effects of light
- photodecomposition:
- photodisintegration:
- photodissociation: chemical reaction in which photons break chemical bonds
- photodissociation clouds:
- photodissociation region (PDR): cloud of partially-ionized atomic hydrogen
- HII region (HII): cloud of partially-ionized atomic hydrogen
- photodissociation: chemical reaction in which photons break chemical bonds
- photoelectric effect:
- photoevaporation: dispersal of a gas from UV radiation
- photoheating:
- photoionization: photon striking neutral atom expelling an electron
- photolysis:
- photometer: instrument measuring brightness
- Photometric LSST Astronomical Time-series Classification Challenge:
- photometric redshift (photo-z): method of estimating redshift without spectroscopy
- photometric system: specification of a set of filters/passbands
- photometry: studying starlight through bandpass filters
- photon: quantum of light, i.e., light as a particle
- baryon: protons, neutrons, and other three-quark particles
- particle: very small thing
- quantum: minimal amount of something that triggers a reaction
- standard model: model of elementary particles including quarks
- supersymmetry: extension to standard model of particle physics
- photon counting: sensing EMR down to the photon level
- photon epoch:
- recombination: time when the universe's ionized hydrogen atoms neutralized
- photon noise: variation in light measurement due to its quantum nature
- photon ray:
- cosmic rays (CR): very-high-energy particles from beyond the solar system
- photon-dominated region:
- photonic ray:
- cosmic rays (CR): very-high-energy particles from beyond the solar system
- photosphere: layer of start from which light propagates
- PHR:
- physical baryon density:
- Lambda-CDM model (ΛCDM,LCDM): Big-Bang cosmological model with a cosmological constant and cold dark matter
- physical cosmology:
- physical dark matter density:
- Lambda-CDM model (ΛCDM,LCDM): Big-Bang cosmological model with a cosmological constant and cold dark matter
- physical libration:
- Enceladus: Saturn moon considered possible carrier of life
- libration: oscillating motion of orbiting bodies relative to each other
- physics:
- 1H: hydrogen isotope with no neutrons
- absorption: removal of photons from a beam of EMR
- absorption coefficient: measure of how much light a substance absorbs
- Alfvén wave: a type of transverse wave along magnetic field lines in plasma
- alpha particle: essentially a helium nucleus stemming from radioactivity
- angstrom (Å): unit of length 10-10 meters
- anisotropy: directional dependence such as temperature variation in the CMB
- antimatter: similar to normal matter but with opposite electrical charge
- arXiv.org: website with physics paper preprints
- atm: unit of pressure
- atomic excitation: atoms with electrons above the ground state
- axion (A0): proposed light, electrically neutral elementary particle
- barycenter: center of mass of two orbiting bodies
- baryon: protons, neutrons, and other three-quark particles
- beta (β): ratio of plasma pressure to magnetic pressure
- beta decay: radioactivity such that an electron or positron is emitted
- Big Bang nucleosynthesis (BBN): creation of atomic nuclei in the very early universe
- binding energy: energy needed to separate two objects
- Birkhoff's theorem: shows GR qualities of a spherically-symmetric mass
- black body (BB): idealized object that reflects no light
- black hole (BH): region of such high mass that light cannot escape
- black-body radiation: continuous spectrum characteristic of the temperature of a body
- blended spectra: an observed spectrum comprising light from multiple objects
- Bohr model: has electrons circling nucleus in quantized orbits
- bolometric luminosity (LBol): total luminosity of an object at all wavelengths
- Boltzmann constant (k,kB): relates particle energy and temperature
- Boltzmann equation: equation relating atomic excitation to temperature
- Bondi radius: radius in which a body moving through a medium will draw it in
- Bose-Einstein statistics: possible distribution of particles not bound by Pauli exclusion
- bow shock: shock wave of a magnetosphere through the surrounding medium
- Cherenkov radiation: radiation from the shock of a charged particle passing through a medium
- chirp mass (Mc): a reduced-mass-like quantity that relates to gravitational waves
- circular polarization ratio (CPR): ratio of circular polarization handedness in reflected radar signal
- Compton scattering: photon collision with a charged particle that emits a different photon
- conservation law: property that remains unchanged by physical phenomena
- continuum emission: continuous spectrum such as black body radiation or bremsstrahlung
- cooling function: function relating a gas's cooling rate to its temperature
- Coriolis force: apparent force in a rotating frame of reference
- cosmic string: rent in spacetime
- cosmological constant (Λ): force counteracting the universe's inward gravitational pull
- cosmological time dilation: very distant events appear to take longer
- Coulomb's law: static electrical force relation
- cross section: "area" representation of probability of an interaction of particles
- curvature radiation: synchrotron-like radiation when particles follow curved field lines
- cyclotron radiation: radiation emitted when charged particles are accelerated
- dalton (Da,u): mass unit used on atomic scale
- dark energy: energy theorized to accelerate the expansion of the universe
- dark matter: matter hypothesized to provide galaxies with mass that can't be viewed
- dark matter halo: hypothetical dark matter throughout and surrounding a galaxy
- de Broglie wavelength: wavelength of a particle's matter wave
- degeneracy: general word meaning a violation of normal rules
- degeneracy weight: number of quantum states with same energy level
- degree of ionization: fraction of material consisting of ions
- deuterium (D): hydrogen isotope with one neutron
- DGP gravity: alternative theory of gravity addressing "dark energy"
- diffraction: effect of an obstacle on a wave
- diffraction limited: telescope limited only by the laws of diffraction
- diffusion: the spreading of particles toward an even distribution
- discontinuous Galerkin method: computational method for PDEs handling discontinuities
- Doppler broadening: broadening of spectral lines due to velocities of the photon sources
- Doppler shift: wave frequency difference due to relative velocity difference with source
- dynamical friction: drag produced by gravitational interaction with surrounding objects
- dynamical instability: situation where a perturbation makes itself larger
- dynamo: mechanism for generating magnetic fields around astronomical bodies
- Eddington approximation: approximation of a star's internal EMR's divergence from isotropic
- Eddington luminosity: maximum luminosity at which radiation force overcomes gravity
- effective temperature (Teff,Teff): temperature of an equivalent black body in terms of total radiation
- 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
- Einstein-de Sitter model: universe tuned to the smallest expansion that continues forever
- electric field (E): electric force as distributed over a space
- electromagnetic radiation (EMR): radiation such as light, radio, X-rays
- electromagnetic spectrum: spectrum of EMR
- electromagnetism (EM): electricity and magnetism and their interaction
- electron degeneracy: the condition of electrons supported solely by the Pauli exclusion principle
- electron orbital: a nucleus's "locations" where an electron can orbit
- electron scattering: any process that changes the course of an electron
- electron screening: reduction of effective charge of a nucleus by nearby electrons
- electroweak: single conception including both electromagnetic and weak forces
- element: class of atom based on its number of protons
- emission: addition of photons to a beam of EMR
- emission coefficient (j): measure of how much light a substance emits
- endothermic reaction: reaction that absorbs heat
- energy density: energy per unit volume
- entropy (S): relative measure of the amount of usable energy available
- equation of radiative transfer (RTE): equation describing energy transfer by EMR
- equation of state (EoS): equation relating temperature, pressure, and volume
- equilibrium temperature (Teq,Teq): temperature a planet would have if it were an externally-heated black body
- erg: CGS unit of energy
- evaporation: particles escaping, e.g., liquid molecules escaping as gas
- expansion fan: the "sound" of a supersonic flow flowing around a convex corner
- false vacuum: apparent QM vacuum
- field lines: lines showing the pattern of a mathematical field
- finite difference method (FDM): means of estimating calculus and differential equation solutions
- finite element method (FEM,FEA): computational method for PDEs suited to physical problems
- finite volume method (FVM): computational method to PDEs especially suited to fluid dynamics
- fluorescence: mechanism by which molecules emit a longer wavelength than they absorb
- flux: flow rate per unit area
- forbidden line: lines that quantum mechanics disallows for the most part
- fractionation: separation of compounds from a mixture
- fractionation factor: isotope quantity
- frame of reference: region, possibly in motion, from which something is observed/considered
- fusion: formation of an atomic nucleus nuclei from multiple smaller nuclei
- Gamow peak: relative speed most likely to cause atoms to fuse
- gas flow: dynamics of gas, plasma, i.e., compressible fluids
- gauss (G,Gs): measurement of magnetic field β
- general relativity (GR): formula relating gravity, space, time, and mass
- Godunov scheme: computational fluid dynamics method
- gravitational collapse: shrinking of an object from gravitational force
- gravitational constant: indicates how much pull between two masses
- gravitational field: gravitational force as distributed over a space
- gravitational potential (Φ): conceptual field indicating the strength of gravity at each point
- gravitational wave (GW): ripples in the curvature of spacetime propagating as a wave
- gravitational wave background (GWB): combination of weak gravitational waves such as from distant sources
- gravitational wave spectrum: various frequencies of gravitational waves
- gravitational wave strain (h): a measure of the magnitude of a gravitational wave
- gravitational-wave memory: a gravitational wave that does not return
- gravity: theory that mass attracts
- gravity wave: wave in fluid where restoring force is gravity
- greenhouse effect: mechanism that boosts temperature through selective blocking of EMR
- Hall effect: voltage generated by interacting current and magnetic field
- homologous collapse: collapse of a uniform sphere of material
- hydrodynamics: study of liquids in motion
- hydrostatic equilibrium: state of a fluid body when forces are such that the fluid is at rest
- ice: solid state of water
- intensity: power reaching a surface from a specific source
- interference: result of interaction of waves
- interferometer: device detecting properties of electromagnetic waves by detecting interference between waves
- internal gravity wave: ripples in a change in density in a fluid
- inverse square law: a value's dependency upon reciprocal of the square of the distance from something
- ionization potential: energy needed to ionize an atom
- isothermal core: core region of a body of all the same temperature
- isotope: subclass of an element with a specific number of nucleons
- jansky (Jy): unit of measurement of spectral flux density
- jet: stream of matter from an astronomical body
- joule: SI unit of energy
- Kelvin-Helmholtz mechanism: release of energy from gravitational collapse
- kinetic energy (KE): an object's energy due to its motion
- Kirchhoff's laws: laws regarding the source of spectral lines
- Kramers opacity law: opacity's relation to density and temperature
- Lorentz force: force on a point charge due to magnetic fields
- Lorentz transformation: equations describing the effect of relative motion on length and velocity
- Love number: measures of rigidity of a body
- Lyapunov time: timescale over which a dynamical system is chaotic
- Mach number: ratio of a flow with the speed of sound
- magnetic energy spectrum: spatial spectral density of the energy associated with magnetic fields
- magnetic field: magnetic force as distributed over a space
- magnetic field strength (H): a field associated with magnetism
- magnetic flux (B): total magnetism passing through a surface
- magnetic flux density (B): vector field describing magnetism in relation to the Lorentz force
- magnetic induction: voltage across a conductor induced by changing magnetic field
- magnetic reconnection: change in magnetic topology within a fluid
- magnetohydrodynamics (MHD): dynamics of electrically conducting fluids
- magnetorotational instability (MRI): instability in the fluid of a disk from MHD effects
- magnetosonic wave: a type of sonic wave in a plasma
- mass: object's quality that determines the effects of forces and gravity
- mass spectrometer: device to determine the mass of molecules in a mixture
- Maxwell's equations: four equations describing electricity and magnetism
- Maxwell-Boltzmann distribution: distribution of velocities of gas particles
- mean free path: average length that a particle travels before interaction
- metric: mathematical generalization of the concept of distance
- Michelson interferometer: device to measure small changes in distance or light speed
- Mikheyev-Smirnov-Wolfenstein effect (MSW effect): neutrino oscillation between three flavors
- modified Newtonian dynamics (MOND): alternative theory of gravity addressing "dark matter"
- moment of inertia factor: characterization of mass distribution within a planet
- nanohertz gravitational waves: size of GWs that pulsar-timing observations might catch
- NBODY: code to carry out N-body simulations
- neutrino (ν): light, electrically neutral elementary particle
- neutron capture: combination of an atomic nucleus and a neutron
- neutron scattering: scattering of neutrons by atomic nuclei
- neutron spectrometer: device determining the energy of received free neutrons
- nuclear energy generation rate (ε): fusion power per unit mass
- nucleosynthesis: creation of atomic nuclei
- opacity: a measure of opaqueness of a material
- optical depth (τ): a measure of opaqueness of a path of light
- oscillator strength: fraction expressing QM's contribution to the probability of absorption
- partial differential equation (PDE): equation constructed as if the variables differentiated are independent
- particle: very small thing
- particle spectrometer: device to determine the characteristics of incoming particles
- partition function (Z): scale factor for Boltzmann factors
- Pauli exclusion principle: fermions in a quantum system cannot have identical quantum numbers
- phase space: space of all possible states of a system
- phase transition: transformation from one state of matter to another
- photoevaporation: dispersal of a gas from UV radiation
- photoionization: photon striking neutral atom expelling an electron
- photon: quantum of light, i.e., light as a particle
- pion (π): first type of meson discovered
- Planck constant (h): quantum of action in quantum mechanics
- Planck function: yields black body curve
- plasma: state of matter where atoms are not part of molecules and are ionized
- plasma frequency: frequency of electron plasma oscillation
- polarization: property of waves that oscillate in a particular direction
- polarization modes: electric and magnetic aspects of the polarization of electromagnetic radiation
- potential energy (PE): an object's energy that can be released
- Poynting vector (S): measures directional energy flux density
- Q factor: measure of oscillator's damping
- quadratic field strength: a measure of a star's varying magnetic field
- quantum: minimal amount of something that triggers a reaction
- quantum mechanics (QM): modern mechanical theory of small things, on the scale of atoms
- quantum mixing: means by which one particle spontaneously changes to another
- quantum number: number representing a conserved quantity
- quantum tunneling: quantum mechanical effect of particles passing through a barrier
- radiation hydrodynamics (RHD): hydrodynamics plus the affects of EMR
- radiative transfer (RT): energy transfer in the form of electromagnetic radiation
- radioactive dating: determining the age of a substance that has a radioactive component
- radioactive decay: changes in atomic nuclei that happen over time
- radioactive heating: a source of heat of some planets and moons
- radiometer equation: shows how long to observe a radio source
- ram pressure: pressure on a body moving through a fluid
- Rayleigh-Jeans law: yields approximation of black body curve
- reduced mass: the reciprocal of the sum of the reciprocals of the masses of two objects
- refractory material: material with high condensation temperature
- relativistic energy: energy of an object including relativistic effects
- relativistic invariance: quantity that remains the same regardless of frame of reference
- relativistic momentum: momentum of an object including relativistic effects
- relativistic speed: a good fraction of the speed of light
- relativity: physics models accommodating the constancy of the speed of light
- rest wavelength: normal wavelength observed when not moving in relation to the source
- Saha equation: equation relating ionization to temperature
- Salpeter timescale: timescale for black hole growth
- Schuster-Schwarzschild model: approximation of a star's internal EMR's divergence from isotropic
- shock wave: abrupt propagating disturbance in a fluid
- siderophile: material that dissolves in molten iron
- solar constant: flux from the Sun at 1 AU
- sound speed: speed at which compression waves traverse a gas
- source function (S): measure indicating the effect of a material on EMR passing through
- spacetime: four dimensions: time and the three space dimensions
- specific heat: ratio of added temperature to added heat for a material
- specific volume: ratio of volume to mass
- spectral energy distribution (SED): function or plot of brightness at each wavelength in the spectrum
- spectral line energy distribution (SLED): function or plot of brightness of lines in a spectrum
- speed of light (c): fundamental constant measured as the speed at which light travels
- spin (ms): an angular-momentum quantum number
- spiral density wave: spiral structure that can form in disks
- standard model: model of elementary particles including quarks
- state of excitation: energy level of something above the minimum
- state of ionization: difference in an ion's electron count versus proton count
- statistical mechanics: mechanical behavior based upon probability
- Stefan-Boltzmann constant (σ): relates radiation power to temperature and surface area
- strong force: force that holds quarks and nuclei together
- strong-field gravity: gravity much stronger than in the solar system such as near a black hole
- sublimation: single material phase transition from solid to gas
- supercooling: cooling water below freezing point without it freezing
- superluminal motion: faster-than-light movement
- supersymmetry: extension to standard model of particle physics
- suprathermal: having more energy than would be created by thermal excitation
- symmetry breaking: loss of symmetry, such as due to loss of stability in a regime change
- synchrotron radiation: radiation emitted when high-speed charged particles are accelerated
- synchrotron self-Compton (SSC): charged particle cloud scattering its own synchrotron-produced photons
- telegrapher's equations: two equations describing a transmission line
- temperature: measure of heat in matter
- tesla (T): unit of magnetic flux density
- Theory of Everything (TOE): single law explaining the four forces of nature
- thermal inertia: a measure of a material's ability to absorb heat through conduction
- thermodynamic equilibrium (TE): state of a system with no net heat flows
- thermodynamics: physics of heat and energy
- Thomson optical depth: a measure of affects of Thomson scattering
- Thomson scattering: elastic scattering of photons by a charged particle
- tidal force: affect of a third body on the gravitational force between two bodies
- tidal heating: heating due to friction from motions caused by tidal force
- time dilation: relativity's ability to make time longer
- time standard: method of designating points in time and quantifying time periods
- turbulence: irregular flow of a fluid
- turbulent pressure: pressure component due to the presence of turbulence
- two-stream approximation: approximation of a star's internal EMR's divergence from isotropic
- valley of beta stability: set of isotopes not prone to beta decay
- VHE: 100 GeV or more
- virial parameter: calculated quantity showing whether a cloud is gravitationally bound
- virial theorem: average kinetic energy equals half the average negative potential energy
- volatile material: material with low condensation temperature
- vortensity (PV): ratio of vorticity to mass density
- vortex: fluid region where the flow is spinning
- wave-particle duality: at atomic scale, things act like both particles and waves
- Wien's displacement law: temperature times wavelength with maximum intensity equals a constant
- worldline: path of an object through space and time
- wormhole: connection between two regions in a curved space
- ZAMO frame: a frame of reference that is not rotating
- physisorption:
- PI:
- Pi of the Sky: survey aimed at finding gamma-ray-burst visual counterparts
- Pi3 Orionis:
- F-type star (F): type of star with about 1.5 times the mass of the Sun
- Pico Dos Dias Observatory:
- Pico dos Dias Survey (PDS): survey aimed to find T-Tauri stars
- PIMS:
- pink noise:
- red noise: noise tending toward lower frequencies
- Pinwheel Galaxy (M101): easily-observed spiral galaxy
- pion (π): first type of meson discovered
- Pioneer:
- Callisto: well-known Jupiter moon
- Europa: well-known Jupiter moon
- Ganymede: well-known Jupiter moon
- gravity sounding: measuring a planet's gravitation field by study of nearby probe flights
- Io: well-known Jupiter moon
- Saturn: second largest planet in the solar system
- PIONIER:
- PISCES:
- MMT: 6.5 meter telescope at Mt. Hopkins, Arizona
- Pisces-Cetus Supercluster Complex:
- Pisces-Pegasus Filament:
- Pisces-Perseus Supercluster:
- PISN:
- Pixel-lensing Observations with the Isaac Newton Telescope-Andromeda Galaxy Amplified Pixels Experiment:
- PIXL:
- PK:
- PK67:
- PKS:
- Parkes Catalog (PKS): catalog of from 1960s-1990 of radio sources in southern hemisphere
- plage:
- plan:
- Planck: microwave telescope in space
- Planck constant (h): quantum of action in quantum mechanics
- Planck function: yields black body curve
- Planck hole:
- black hole (BH): region of such high mass that light cannot escape
- Planck length:
- Planck mass:
- mass: object's quality that determines the effects of forces and gravity
- Planck constant (h): quantum of action in quantum mechanics
- Planck time:
- Planck's constant:
- Planck's law:
- plane of reference:
- plane parallel wave:
- plane wave: simplified wave concept useful for modeling
- plane wave: simplified wave concept useful for modeling
- plane-parallel atmosphere: simplified atmosphere model ignoring its curvature around the body
- planemo:
- PLANET:
- dwarf planet: round like a planet, only smaller
- Earth: third solar system planet from the Sun
- International Astronomical Union (IAU,UAI): association of professional astronomers
- Jupiter: largest planet in the solar system
- Mars: well-explored planet in the solar system
- Mercury: inner-most and smallest planet in the solar system
- Neptune: outer-most solar system planet
- planet: round object orbiting a star that clears out its own orbital path
- Probing Lensing Anomalies Network (PLANET): survey that recorded microlensing event lightcurves
- Saturn: second largest planet in the solar system
- Uranus: second outer-most solar system planet
- Venus: second inner-most planet in the solar system
- Planet 10:
- Planet 9:
- planet emission:
- planet formation: process by which planets form
- Planet Hunters (PH): crowdsourcing website to identify galaxy types from surveys
- planet multiplicity:
- Planet Nine: theoretical planet beyond Neptune
- planet rotation:
- planet structure: internal structure of planets
- planet type: methods of classifying planets
- planet-disk interaction:
- planet-planet scattering:
- planetary differentiation: stratification of the materials making up a planet
- planetary disk:
- planetary embryo: object that may grow into a future planet
- planetary equilibrium temperature:
- planetary mass object (PMO): has the mass of a planet
- planetary migration: change in planet's orbit
- planetary nebula (PN, PNe): gas shell ejected by a red giant
- planetary nebula luminosity function (PNLF): model used in distance estimation
- planetary nebulae:
- planetary protection: the principle of avoiding contaminating planets with Earth life forms
- planetary rotation:
- planetary science: study of planet characteristics
- planetary system: all the planets orbiting a star
- star system: a star and what's gravitationally bound to it
- Planetary Transits and Oscillations of stars:
- PLATO: planned observatory-satellite aimed at finding exoplanets
- planetesimal: objects held together by gravity that combine to form planets
- planetoid: an asteroid or physically similar body
- planets:
- Planets Around Low-mass Stars:
- PALMS: survey to find exoplanets for direct imaging
- planetshine:
- earthshine: reflected and emitted electromagnetic radiation from Earth
- PlanetWRF:
- MarsWRF: Mars-oriented general circulation model
- plasma: state of matter where atoms are not part of molecules and are ionized
- plasma frequency: frequency of electron plasma oscillation
- plasma physics:
- beta (β): ratio of plasma pressure to magnetic pressure
- PLASTIC:
- STEREO: two-satellite system to observe the Sun
- PLAsTiCC:
- plate measuring machine (APM): machine to measure position of images on photographic plates
- plate scale: relation between angle and distance across an image
- plate tectonics:
- Plateau de Bure:
- Plateau de Bure High-z Blue Sequence Survey:
- PHIBSS: survey of CO in distant galaxies
- Plateau de Bure Interferometer (PdBI): 6-dish interferometer in French Alps
- platinum:
- r-process: synthesization of elements through neutron capture faster than beta decay
- PLATO: planned observatory-satellite aimed at finding exoplanets
- PLATO 2.0:
- PLATO: planned observatory-satellite aimed at finding exoplanets
- PLS:
- Voyager: space probes to observe planets and the edge of the solar system
- plutino:
- Pluto: dwarf planet formerly listed as one of the nine planets
- PLUTO Code: fluid-dynamic simulation code
- Pluto Telescope:
- plutoid: Pluto-like dwarf planet
- plutonium-238 dioxide:
- MMRTG: power source for space probes
- PMAS/PPak:
- CALIFA: spectroscopic map of 600 galaxies
- PMF:
- PMN:
- PMO:
- PMS:
- PMS object:
- PN:
- PNe:
- PNG:
- PNLF:
- Poincaré map:
- Poincaré section: pattern formed by a the locations an orbiting body passes through a plane
- Poincaré section: pattern formed by a the locations an orbiting body passes through a plane
- point mass:
- mass: object's quality that determines the effects of forces and gravity
- point spread function:
- PSF fitting: untangling airy disks to gain effective resolution
- point spread function fitting:
- PSF fitting: untangling airy disks to gain effective resolution
- point spread function subtraction:
- POINT-AGAPE: survey of M31 for microlensing
- point-spread function (PSF): function describing an optical system's response to a point of light
- pointed observation:
- slew survey: survey conducted by imaging during a telescope's repointings
- pointing error (PE): discrepancy in telescope's aim
- Poisson distribution: statistics on count of events happening within a given interval
- Poisson level:
- photon noise: variation in light measurement due to its quantum nature
- Poisson noise:
- photon noise: variation in light measurement due to its quantum nature
- polar:
- polar cell:
- Hadley cell: circulation pattern of up at the equator, out, down, and back
- polar cyclone: storm centered on the pole
- polar jet:
- jet: stream of matter from an astronomical body
- polar moment of inertia:
- polar vortex:
- Hadley cell: circulation pattern of up at the equator, out, down, and back
- Polar-ring Catalog (PRC): 1990 catalog of polar-ring galaxies
- polar-ring galaxy: galaxy encircled by a ring of stars
- POLARBEAR: instrument to map CMB polarization
- Simons Observatory: planned astronomy facility on Atacama Desert for ACT and other telescopes
- POLARBEAR-2:
- Simons Observatory: planned astronomy facility on Atacama Desert for ACT and other telescopes
- polarimeter:
- Mimir: multi-function near-infrared instrument on Perkins Telescope
- POLARBEAR: instrument to map CMB polarization
- polarimetry: measurement of polarization of EMR
- polarimeters:
- 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
- Polish:
- All Sky Automated Survey (ASAS): Polish survey of 20,000 objects brighter than 14 magnitude
- OGLE: survey searching for microlensing transients
- Pi of the Sky: survey aimed at finding gamma-ray-burst visual counterparts
- poloidal:
- polycyclic aromatic hydrocarbon (PAH): hydrocarbons consisting of meshes of benzene rings
- polycyclic aromatic hydrocarbon emissions:
- PAH emissions: infrared emission from polycyclic aromatic hydrocarbons in gas clouds
- polygonal ground: crack pattern in ground forming polygons due to freezing
- polygonal patterned ground:
- polytrope:
- polytropic:
- Pop I:
- Pop II:
- Pop III:
- Population I:
- Population II:
- Population III:
- population statistics:
- population synthesis simulation:
- position angle: indication of a direction across the celestial sphere
- position-position space:
- position-position-position space:
- position-position-velocity space (PPV): 3d space using velocity as one of the three dimensions
- position-velocity space:
- positional astronomy:
- astrometry: precise measurement of the position and movement of stars
- Positions and Proper Motions Star Catalog:
- positive feedback:
- positron:
- antimatter: similar to normal matter but with opposite electrical charge
- beta decay: radioactivity such that an electron or positron is emitted
- plasma frequency: frequency of electron plasma oscillation
- POSS:
- POSS-I:
- POSS-II:
- post main sequence star: star evolved beyond its main sequence phase
- post-common envelope binary (PCEB): binary star system showing unusual stellar evolution
- posterior:
- posterior density:
- posterior distribution:
- posterior mass:
- posterior probability:
- potassium:
- potassium/thorium ratio (K/Th ratio): indication of thermal history
- potential energy (PE): an object's energy that can be released
- potential vorticity:
- vortensity (PV): ratio of vorticity to mass density
- potentially hazardous object:
- POTS:
- pounds-force:
- Powderday:
- power:
- focal length: length from optical element to focal plane
- plate scale: relation between angle and distance across an image
- watt (W): SI unit of power
- power law: relationship with one quantity a power of another
- power law spectrum:
- cosmic rays (CR): very-high-energy particles from beyond the solar system
- power law: relationship with one quantity a power of another
- power spectral density:
- power spectrum:
- Poynting flux:
- Poynting flux jet:
- Poynting flux vector:
- Poynting vector (S): measures directional energy flux density
- Poynting-Robertson drag:
- Poynting-Robertson effect: force slowing dust grains orbiting a star
- PP chain:
- PP disk:
- PP space:
- PP-chain:
- PPD:
- PPM:
- PPM Star Catalogue: 1991 astrometric catalog with proper motions
- PPN:
- PPP space:
- PPS:
- Voyager: space probes to observe planets and the edge of the solar system
- PPTA:
- PPTA4:
- PPV:
- PQ:
- PRA:
- Voyager: space probes to observe planets and the edge of the solar system
- Prandtl-Meyer expansion fan:
- expansion fan: the "sound" of a supersonic flow flowing around a convex corner
- praseodymium:
- PRC:
- pre-main-sequence star (PMS): star not yet with a nuclear reaction
- Pre-OmegaTranS (POTS): transit search using MPG/ESO Telescope
- precession: periodic change in a body's rotation or orbit
- precession constant:
- precession: periodic change in a body's rotation or orbit
- precession of the equinoxes:
- precession: periodic change in a body's rotation or orbit
- Precision Array for Probing the Epoch of Reionization:
- PAPER: radio interferometer for 21cm measurement
- precision photometry:
- photometry: studying starlight through bandpass filters
- preplanetary disk:
- preplanetary nebula:
- pressure:
- pressure broadening:
- pressure integral: integral relating pressure to a gas's characteristics
- pressure scale height:
- PRESTO:
- prevailing winds:
- PRIDE:
- JUICE: mission to Jupiter in development
- primary: central body of a system such as the Sun in the solar system
- primary body:
- primary: central body of a system such as the Sun in the solar system
- primary eclipse:
- primary mirror: main mirror in a reflecting telescope
- prime focus: reflecting telescope with no secondary mirror
- Prime Focus Spectrograph:
- prime meridian:
- meridian: circle around the Earth passing through both poles
- Prime-Cam:
- CCAT-prime (CCAT-p): planned 6 meter submillimeter telescope in Chile
- primordial abundance:
- primordial atmosphere:
- primordial binary:
- primordial black hole:
- black hole (BH): region of such high mass that light cannot escape
- primordial gravitational wave:
- primordial GW:
- primordial non-Gaussianity.:
- non-Gaussian (NG): something requiring adjustment from the gaussian function
- primordial nucleosynthesis:
- Principal Galaxies Catalog (PGC): modern catalog of more than 70k galaxies
- principal investigator (PI): lead researcher in a scientific endeavor
- principle component:
- PCA analysis: an automatable method of determining galaxy morphology
- principle component analysis:
- PCA analysis: an automatable method of determining galaxy morphology
- principle curve:
- PCA analysis: an automatable method of determining galaxy morphology
- principle quantum number:
- electron orbital: a nucleus's "locations" where an electron can orbit
- spin (ms): an angular-momentum quantum number
- prior:
- prior density:
- prior distribution:
- prior mass:
- prior probability:
- prism:
- grism: combination of a grating and a prism
- probability density function (PDF): shows probability of taking a particular value from a continuous range
- probability mass function:
- probe:
- Mars 2020: Mars rover in planning
- Mars Express: Mars probe launched by ESA in 2003
- Mars Global Surveyor (MGS): Mars probe launched by NASA in 1996
- Mars Reconnaissance Orbiter (MRO): Mars probe launched by NASA in 2005
- MMX: Japanese probe to bring back a sample of a Martian moon
- Phoenix: Mars probe launched by NASA in 2007 with lander
- radar: probe based on reflecting radio waves
- Voyager: space probes to observe planets and the edge of the solar system
- Probing Lensing Anomalies Network (PLANET): survey that recorded microlensing event lightcurves
- Procyon: brightest star in Canis Minor
- Procyon A:
- F-type star (F): type of star with about 1.5 times the mass of the Sun
- prograde orbit:
- prograde wind:
- project:
- Bcool: project studying stellar magnetism
- Bolshoi simulation: cosmological simulation
- DASCH: project to digitize Harvard astronomy plates
- EAGLE: simulation of galaxy formation and evolution
- ESSENCE: survey using supernova data to study dark energy
- FIRE Simulations: high resolution simulation of galaxies
- LasDamas: simulations of large scale evolution of dark matter and galaxies
- MOJAVE: program to monitor AGN jet radio brightness and polarization
- RHAPSODY: simulation of galaxy cluster dark-matter halos
- Supernova Cosmology Project (SCP): used supernova data to determine a history of the universe's expansion
- TiNy Titans (TNT): study of dwarf galaxy pairs
- Project 1640:
- projected separation: minimal distance between two distant objects close to each other
- Prometheus:
- PROMETHEUS/VERTEX: hydrodynamic simulation system
- prominence eruption:
- proper distance:
- relativity: physics models accommodating the constancy of the speed of light
- proper length:
- relativity: physics models accommodating the constancy of the speed of light
- proper motion: apparent motion in relation to the position of the Sun
- proper time:
- relativity: physics models accommodating the constancy of the speed of light
- proplyd:
- protected region: an area around a body where an orbit can be stable
- protium:
- 1H: hydrogen isotope with no neutrons
- proto-planetary disk:
- protogalaxy: gas cloud forming a galaxy
- proton:
- baryon: protons, neutrons, and other three-quark particles
- particle: very small thing
- standard model: model of elementary particles including quarks
- proton synchrotron radiation:
- proton-proton chain: fusion reaction chain turning hydrogen into helium
- protoplanet: simplest, least-developed object classified as a planet
- protoplanetary disk (PPD): disk of dust and gas around a young star or protostar
- protoplanetary nebula (PPN): AGB phase before planetary nebula
- protostar: contracted mass of gas that will become a star
- Elias 2-27: much-studied YSO
- GG Tau: much-studied quadruple star system
- HL Tau: much-studied T-Tauri star
- T Tauri: variable star taken as example of young star
- TW Hydrae (TW Hya): nearest T-Tauri star
- protostars:
- provisional designation: way to designate newly discovered solar system objects
- Proxima b: exoplanet orbiting Proxima Centauri
- Proxima Centauri:
- Proxima Centauri b:
- Proxima b: exoplanet orbiting Proxima Centauri
- PS1:
- PS2:
- PS4:
- PSD:
- PSF:
- PSF fitting: untangling airy disks to gain effective resolution
- PSF subtraction:
- PSO:
- PSO J246.4222+15.4698:
- PSPC:
- ROSAT: 1990s German space X-ray telescope
- PSR:
- pulsar (PSR): astronomical body whose electromagnetic radiation displays a cycle
- PSR 1913+16:
- Hulse-Taylor Binary (PSR B1913+16,PSR J1915+1606, PSR 1913+16): binary system consisting of a pulsar and neutron star
- PSR 1957+12: pulsar with first discovered planet system
- PSR 1957+12 a:
- PSR 1957+12: pulsar with first discovered planet system
- PSR 1957+12 b:
- PSR 1957+12: pulsar with first discovered planet system
- PSR 1957+12 c:
- PSR 1957+12: pulsar with first discovered planet system
- PSR B0531+21:
- PSR B1913+16:
- Hulse-Taylor Binary (PSR B1913+16,PSR J1915+1606, PSR 1913+16): binary system consisting of a pulsar and neutron star
- PSR B1957+12:
- PSR 1957+12: pulsar with first discovered planet system
- PSR B1957+20:
- Black Widow Pulsar (B1957+20, PSR J1959+2048, PSR B1957+20): binary system consisting of a pulsar and small companion
- PSR J1300+1240:
- PSR 1957+12: pulsar with first discovered planet system
- PSR J1915+1606:
- Hulse-Taylor Binary (PSR B1913+16,PSR J1915+1606, PSR 1913+16): binary system consisting of a pulsar and neutron star
- PSR J1959+2048:
- Black Widow Pulsar (B1957+20, PSR J1959+2048, PSR B1957+20): binary system consisting of a pulsar and small companion
- Psyche: planned space mission to orbit an asteroid
- PTA:
- PTF:
- PTI:
- Ptolemy:
- Rosetta: space probe that visited a comet
- Public ESO Spectroscopic Survey of Transient Objects:
- PESSTO: survey for transients carried out on the NTT
- Publications of the Astronomical Society of Japan (PASJ): bimonthly journal
- PUEO/KIR:
- Puerto Rican Ultimate Pulsar Processing Instrument:
- PUPPI: Arecibo radio-telescope instrument aimed at observing pulsars
- Puerto Rico:
- pulsar (PSR): astronomical body whose electromagnetic radiation displays a cycle
- Black Widow Pulsar (B1957+20, PSR J1959+2048, PSR B1957+20): binary system consisting of a pulsar and small companion
- Hulse-Taylor Binary (PSR B1913+16,PSR J1915+1606, PSR 1913+16): binary system consisting of a pulsar and neutron star
- J1713-0747: binary system with millisecond pulsar and white dwarf
- PSR 1957+12: pulsar with first discovered planet system
- pulsar holography:
- pulsar timing array (PTA): cooperating set of pulsar timing observatories
- pulsar timing data:
- pulsars:
- pulsating star: variable star that varies through energy pulses
- pulsar (PSR): astronomical body whose electromagnetic radiation displays a cycle
- pulsation modes:
- pupil size:
- exit pupil: size of the image as presented to the eye
- PUPPI: Arecibo radio-telescope instrument aimed at observing pulsars
- purity:
- completeness: measure of how many of a survey's objects of a certain magnitude have been detected
- purity limit:
- completeness: measure of how many of a survey's objects of a certain magnitude have been detected
- PV:
- vortensity (PV): ratio of vorticity to mass density
- PV space:
- PWS:
- Voyager: space probes to observe planets and the edge of the solar system
- PyDISORT:
- DISORT: simulation of radiative transfer in an atmosphere
- pyramid sensor:
- python:
index