Term Index (S)
- S:
- entropy (S): relative measure of the amount of usable energy available
- Poynting vector (S): measures directional energy flux density
- S-type star (S): type of star with lines indicating zirconium
- sensitivity function (S): function of wavelength giving the sensitivity of an instrument
- siemens (S): SI unit of electrical conductance
- source function (S): measure indicating the effect of a material on EMR passing through
- spectral flux density (S): flux or power of radiation per unit area per unit wavelength
- sulfur (S): metal, S, atomic number 16
- S Doradus variable:
- S orbital:
- Sérsic index:
- Sérsic profile: model of the relative surface brightness across a galaxy
- Sérsic law:
- Sérsic profile: model of the relative surface brightness across a galaxy
- Sérsic model:
- Sérsic profile: model of the relative surface brightness across a galaxy
- Sérsic profile: model of the relative surface brightness across a galaxy
- S-class:
- S-index:
- s-process: synthesization of elements through neutron capture and beta decay
- S-type star (S): type of star with lines indicating zirconium
- S/m:
- siemens (S): SI unit of electrical conductance
- S/N:
- S0:
- S5:
- s51 Pegasi:
- S1:
- S2:
- S3:
- S4:
- SN:
- SA:
- AGILE: Italian space gamma-ray observatory
- IRAS: 1983 satellite that surveyed the sky in infrared
- spiral galaxy: flat galaxy with spiraling arms
- SAAO:
- SAB:
- SABER:
- TIMED: space probe observing Earth upper atmosphere for solar effects
- SABOCA:
- SAC:
- Sachs-Wolfe effect (SWE,SWeffect): gravitational redshift of the CMB
- Sacramento Peak:
- sad trombone:
- fast radio burst (FRB,FRT): astronomical high energy radio pulses of a few milliseconds
- SAFARI:
- SPICA: plan for a future space IR telescope
- Sag DEG:
- SagDIG:
- SAGE: survey of gas and dust in the Magellanic Clouds
- SAGE-LMC:
- SAGE: survey of gas and dust in the Magellanic Clouds
- SAGE-SMC:
- SAGE: survey of gas and dust in the Magellanic Clouds
- SAGE-Spec:
- SAGE: survey of gas and dust in the Magellanic Clouds
- Sagittarius A:
- Sagittarius A*:
- Sagittarius Dwarf Elliptical Galaxy (Sgr dE): satellite galaxy of the Milky Way
- Sagittarius Dwarf Irregular Galaxy (SagDIG): most distant galaxy in the Local Group
- Sagittarius Dwarf Spheroidal Galaxy:
- Sagittarius Stream:
- Sagittarius Window Eclipsing Extrasolar Planet Search (SWEEPS): transit search using HST time
- Sagittarius-Carina Arm:
- spiral arm: long, winding visible structure within a spiral galaxy
- Saha equation: equation relating ionization to temperature
- Saha ionization equation:
- Saha-Langmuir equation:
- Saiph:
- Orion: well-known constellation in the northern hemisphere
- Salpeter function:
- Salpeter IMF:
- Salpeter time:
- Salpeter timescale: timescale for black hole growth
- SALT:
- SALTICAM:
- SAM:
- SAM QC:
- SAM-QMS:
- SAM-TLS:
- SAMI:
- Sample Acquisition System:
- CAESAR: planned space mission to return a sample of a comet
- Samuel Oschin Telescope:
- SAND:
- Santa Cruz:
- SAO:
- SAO Star Catalog: 1960s catalog
- SAO/ASIAA:
- SAO/NASA Astrophysics Data System:
- Sardinia Radio Telescope (SRT): Italian large single-dish radio telescope
- SAS:
- CAESAR: planned space mission to return a sample of a comet
- SAS 1:
- Uhuru: 1970 satellite X-ray telescope
- SAS-A:
- Uhuru: 1970 satellite X-ray telescope
- SASSy:
- SCUBA: submillimeter instrument on James Clark Maxwell Telescope
- SAT:
- satellite:
- exosatellite: natural satellite not in the solar system
- moon: a planet's natural satellite, such as Earth's
- satellite galaxies:
- satellite galaxy: galaxy that orbits a larger galaxy
- satellite plane problem: satellite galaxies inexplicably tend to fall in a plane
- saturation:
- humidity: amount of water vapor in a portion of the atmosphere
- hydrocarbon (HC): any compound of just carbon and hydrogen
- Saturn: second largest planet in the solar system
- Cassini: explorer spacecraft sent to Saturn
- Dragonfly: plan for Titan flying rover
- Enceladus: Saturn moon considered possible carrier of life
- Enceladus Life Finder (ELF): mission to search for life on Saturn moon Enceladus
- giant planet: planet of more than 10 Earth masses
- gravity sounding: measuring a planet's gravitation field by study of nearby probe flights
- helium rain: possible source of heat in giant planet atmospheres
- ring system: disk or set of rings orbiting a planet
- shepherd moon: small moon at outer edge of a ring
- TAM: non-gray-RT 3D model of Titan's atmosphere
- Titan: well-known Saturn moon
- Voyager: space probes to observe planets and the edge of the solar system
- Saturn II:
- Enceladus: Saturn moon considered possible carrier of life
- Saturn V:
- Space Launch System (SLS): launch rocket in development, e.g., for future astronomical projects
- Saturn VI:
- Titan: well-known Saturn moon
- SAURON:
- SAX:
- BeppoSAX: Italian-Dutch space X-ray telescope
- SB:
- SB1:
- SB2:
- SBB:
- Big Bang: theoretical event when the universe expanded from a point
- SBF:
- SBH:
- SBIG STX-6303:
- SBS:
- SBS 0335-052: blue compact galaxy
- SC:
- scalar boson:
- scalar curvature:
- scalar field:
- scalar field dark matter:
- scalar spectral index:
- Lambda-CDM model (ΛCDM,LCDM): Big-Bang cosmological model with a cosmological constant and cold dark matter
- scale:
- scale factor (a): relative size of the universe as a function of time
- scale height (H): measure of exponential falloff
- scan pattern:
- scan speed: the speed at which the telescope changes angle on the sky while observing
- scandium:
- Am star: A-type star with metallic lines
- SCARLET:
- scatter broadening:
- fast radio burst (FRB,FRT): astronomical high energy radio pulses of a few milliseconds
- scattered disk:
- scattered disk object:
- scattered Kuiper belt object:
- scattering: changing the direction of a particle's movement
- emission: addition of photons to a beam of EMR
- scattering coefficient:
- SCExAO:
- SCF:
- Schönberg-Chandrasekhar limit: maximum stellar isothermal helium core mass
- Schechter function:
- luminosity function (LF): function giving number of stars or galaxies at different luminosities
- Schechter luminosity function:
- luminosity function (LF): function giving number of stars or galaxies at different luminosities
- Schiaparelli:
- ExoMars: program to search for signs of life on Mars
- Trace Gas Orbiter (TGO): ESA and Russian Mars orbiter-probe launched in 2016
- Schiefspiegler: type of off-axis reflector telescope
- Schmidt camera: telescope type with a very wide field of view
- Schmidt corrector plate:
- Schmidt law:
- Schmidt Oschin Telescope:
- Schmidt telescope:
- Schmidt-Cassegrain telescope:
- Schmidt-Newton telescope (SNT): type of reflector telescope
- Schmidt-Newtonian telescope:
- Scholz's Star: nearby binary star with red dwarf and brown dwarf
- Schuster-Schwarzschild approximation:
- Schuster-Schwarzschild model: simplified model of a star's production of absorption lines
- Schwarzschild black hole:
- Schwarzschild density:
- Schwarzschild diameter:
- Schwarzschild metric:
- metric: mathematical generalization of the concept of distance
- Schwarzschild object:
- Schwarzschild radius: radius of a black hole's event horizon
- event horizon (EH): surface-shape around a black hole through which light cannot escape
- Schwarzschild throat:
- wormhole: connection between two regions in a curved space
- Schwarzschild wormhole:
- wormhole: connection between two regions in a curved space
- science:
- abundances: relative amounts of each chemical element
- asteroseismology: study of stars through analysis of their pulsation
- astrobiology: study of extra-terrestrial life
- astrometry: precise measurement of the position and movement of stars
- basalt: an igneous rock type that shows rapid cooling
- bathymetry: study and measurement of sea depths
- cosmology: study of the life of the universe
- cryogenic spectroscopy: laboratory spectroscopy of materials cooled to cryogenic temperatures
- extragalactic astronomy: astronomy of other galaxies, galaxy clusters, AGNs, quasars, etc.
- forward model: model producing potential observable values from parameters
- galactic astronomy: astronomy confined to the Milky Way
- geochemistry: the chemistry of the Earth, planets, and moons
- Goddard gravity model (GGM): gravity model produced by Goddard Space Flight Center
- gravimetry: measurement of gravity's strength
- hydrology: study of the movement of water
- in situ: on site
- interferometry: analysis of superimposed EMR waves
- interstellar astrophysics: astronomy of the ISM including dust and clouds
- Kavli Institute: any of a number of science institutes supported by Kavli Foundation
- low frequency radio astronomy: astronomy using the lower end of the radio spectrum
- millimeter astronomy: observation and analysis at wavelengths on the order of a millimeter
- optics: science and technology regarding visible light
- photochemistry: study of the chemical effects of light
- photometry: studying starlight through bandpass filters
- planetary protection: the principle of avoiding contaminating planets with Earth life forms
- planetary science: study of planet characteristics
- plasma astrophysics: includes cosmology, IGM, ISM, HI regions
- polarimetry: measurement of polarization of EMR
- principal investigator (PI): lead researcher in a scientific endeavor
- radio astronomy: astronomy observation and analysis of radio EMR
- relativistic astrophysics: physics applicable to cosmology and strong field gravity
- RMS astronomy: collective term for radio, millimeter, and submillimeter
- scale height (H): measure of exponential falloff
- search for extraterrestrial intelligence (SETI): search for radio signals sent from extraterrestrial sources
- sigma (σ): indication of the confidence level of an experiment
- SIMSTACK: software to correlate intensity maps with sources
- solar physics: study of the physics of the Sun
- spectrography: charting the strengths of different electromagnetic wavelengths
- spectrometry: measuring the strengths of different electromagnetic wavelengths
- spectroscopy: measurement of light with various electromagnetic wavelengths
- stellar astronomy: astronomy of the birth, structure, variety, evolution, and fate of stars
- stratigraphy: study of rock layering
- submillimeter astronomy: astronomy observation and analysis of borderline infrared EMR
- synoptic: general, covering everything
- synthetic photometry: deriving photometry-style data from spectroscopy
- thermodynamics: physics of heat and energy
- tomography: observation of sections of a 3D object
- tortuosity: describes something curved with many twists and turns
- transient astronomy: study of short-term astronomical phenomena
- ultraviolet astronomy: astronomy observation and analysis of UV
- Science Run:
- LIGO: pair of observatories to detect gravitational waves
- scientific notation:
- dex: a number or factor's log base 10
- scintillation:
- scintillator: instrument part designed to respond to high-energy photons
- scintillometer:
- scintillometry: measuring of twinkling
- SCl 117:
- SCl 128:
- SCl 40:
- SCM:
- Scorpius-Centaurus Association:
- Scott effect: bias toward finding clusters that have bright galaxies
- SCP:
- SCR:
- SCT:
- SCUBA: submillimeter instrument on James Clark Maxwell Telescope
- SCUBA-1:
- SCUBA: submillimeter instrument on James Clark Maxwell Telescope
- SCUBA-2:
- SCUBA-2 All Sky Survey:
- SCUBA: submillimeter instrument on James Clark Maxwell Telescope
- SCUBA-2 Ambitious Sky Survey:
- SCUBA: submillimeter instrument on James Clark Maxwell Telescope
- Sculptor Galaxy:
- NGC 253: spiral galaxy 11 million light-years away
- Sculptor Void:
- Sculptor Wall: large slab of galaxies
- Scutum-Centaurus Arm: one of two spiral galaxy arms from the Milky-Way bar
- spiral arm: long, winding visible structure within a spiral galaxy
- Scutum-Crux Arm:
- sd:
- luminosity class: classification of size/luminosity of stars
- subdwarf (sd,VI): star less bright than the main sequence given its spectral class
- SD2:
- Rosetta: space probe that visited a comet
- SDC:
- SDF:
- Subaru Deep Field (SDF): survey of a small region of the sky using the Subaru telescope
- SDI:
- SDO:
- SDOR:
- SDSS:
- SDSSp:
- search for extraterrestrial intelligence (SETI): search for radio signals sent from extraterrestrial sources
- Search for Habitable Planets Eclipsing Ultra-cool Stars:
- SPECULOOS: search for Earth-like exoplanets orbiting nearby dim stars
- sec:
- arcsecond (arcsec,sec,second of arc): a 3600th of an angular degree
- SECCHI:
- STEREO: two-satellite system to observe the Sun
- second:
- arcsecond (arcsec,sec,second of arc): a 3600th of an angular degree
- right ascension (RA): direction coordinate along celestial equator
- Second Byurakan Survey (SBS): 1970s-1990s survey of galaxies and quasars
- second dredge-up:
- dredge-up: stellar convection bringing up fused material
- second of arc:
- arcsecond (arcsec,sec,second of arc): a 3600th of an angular degree
- second order perturbation problem:
- Second Palomar Observatory Sky Survey:
- Second Reference Catalogue of Bright Galaxies:
- secondary anisotropies:
- secondary eclipse: eclipse of a body that also transits
- secondary mirror:
- secondary modes:
- secular: occurring slowly over a long period of time
- Laplace radius (rL): a radius for a stable orbit of a satellite around a planet
- secular GI:
- secular gravitational instability:
- secular motion:
- secular: occurring slowly over a long period of time
- secular parallax:
- parallax: angle due to different lines of sight
- secular resonance:
- orbital resonance: tendency of orbits of multiple bodies to remain in a simple pattern
- secular variation:
- secular: occurring slowly over a long period of time
- SED:
- SED fitting:
- Sedna: distant solar system planetoid discovered in 2003
- Sedov expansion:
- blastwave: spherical shock wave from a small volume
- Sedov length:
- blastwave: spherical shock wave from a small volume
- Sedov-Taylor expansion:
- blastwave: spherical shock wave from a small volume
- Sedov-Taylor phase:
- SEDS:
- SEE:
- TIMED: space probe observing Earth upper atmosphere for solar effects
- seeing: apparent blurring and twinkling of objects seen through atmosphere
- seeing limited:
- diffraction limited: telescope limited only by the laws of diffraction
- seeing: apparent blurring and twinkling of objects seen through atmosphere
- seeing number:
- seeing: apparent blurring and twinkling of objects seen through atmosphere
- segmented mirror: a telescope mirror formed of array of smaller mirrors
- Segue:
- Segue 1:
- Segue 2:
- SEGUE-2:
- seismic waves: waves broadcast through Earth from earthquakes
- seismology:
- selectron:
- supersymmetry (SUSY): extension to standard model of particle physics
- SELENE: 2007-2008 Japanese lunar probe
- Selenological and Engineering Explorer:
- SELENE: 2007-2008 Japanese lunar probe
- self-absorption: EMR absorption by the same substance that emitted it
- semi-analytic model (SAM): cosmological model combining analytic and other methods
- semi-major axis (a): maximum radius of an ellipse
- semi-minor axis:
- semiconductor detector:
- semidetached binary:
- semimajor axis:
- semiregular variable:
- sensitivity function (S): function of wavelength giving the sensitivity of an instrument
- SEP:
- separation:
- SEPIA:
- SEPICA:
- SEQUELS:
- SEQUOIA:
- SERC:
- IRAS: 1983 satellite that surveyed the sky in infrared
- UK Schmidt Survey: photographic survey of the southern hemisphere sky
- Serpens Cloud: molecular cloud with SF regions
- Serpens Main:
- Serpens Molecular Cloud:
- Serpens South:
- Serrurier truss:
- SERVS:
- SESAME:
- Rosetta: space probe that visited a comet
- Set of Identifications:
- SETI:
- SETI Institute:
- Sextans:
- Seyfert:
- Seyfert galaxy: visible active galaxy
- SF:
- SF main sequence:
- SF rate:
- SF region:
- SFE:
- SFG:
- SFH:
- SFH Camera:
- CCAT-prime (CCAT-p): planned 6-meter submillimeter telescope in Chile
- SFM:
- SFR:
- SFRD:
- SFRG:
- SGB:
- SGD:
- ASTRO-H: Japanese space X-ray telescope
- SGL:
- SGR:
- Sgr dE:
- Sgr dSph:
- SGR Dwarf:
- Sgr I Dwarf:
- SGR J1745-2900: magnetar orbiting the Milky Way SMBH
- SGRB:
- gamma-ray burst (GRB): short flashes of gamma rays apparently from outside our galaxy
- GW170817: 2017 gravitational wave detection from a neutron star merger
- SGW:
- sh:
- shell star (sh): type of star with broad and narrow absorption lines
- Sh2:
- Shack-Hartmann sensor:
- Shakura-Sunyaev disk:
- shallow atmosphere models:
- Shane Telescope: 3.05 m reflector telescope at Lick Observatory
- Shapiro delay: EMR delay due to passing near massive object
- Shapiro time delay:
- Shapley-Ames Catalog (SAC): 1932 catalog of contemporary data on 1249 galaxies
- Shapley-Ames Catalog of Bright Galaxies:
- Shapley-Curtis debate:
- great debate: historical debate regarding the nature of galaxies
- SHARAD:
- SHARC:
- SHARC II:
- SHARDS: GTC survey in GOODS-N field for quenched galaxies at z 1-2.3
- SHARP:
- Sharpless Catalog (Sh2): catalog of HII regions found on Palomar plates
- shearing box: method of simulating 3D MHD in disks
- SHeFI:
- SHELA:
- shell: hollow shaped region of some kind of ISM
- shell flash:
- shell star (sh): type of star with broad and narrow absorption lines
- shepherd moon: small moon at outer edge of a ring
- shepherding moon:
- Sher:
- SHERLOC:
- Mars 2020: Mars rover in development for 2020 launch
- SHFI:
- shielding effect:
- SHJ:
- shock:
- shock wave: abrupt propagating disturbance in a fluid
- shock capture scheme:
- shock front:
- shock wave: abrupt propagating disturbance in a fluid
- shock heating:
- shock wave: abrupt propagating disturbance in a fluid
- shock tracer:
- shock wave: abrupt propagating disturbance in a fluid
- shock wave: abrupt propagating disturbance in a fluid
- short gamma ray burst:
- gamma-ray burst (GRB): short flashes of gamma rays apparently from outside our galaxy
- short Rossby wave:
- Kelvin waves: pressure and gravity waves formed by Coriolis force and a barrier
- short-period comet:
- shot noise:
- photon noise: variation in light measurement due to its quantum nature
- shot noise level:
- photon noise: variation in light measurement due to its quantum nature
- Shuttle Pointed Autonomous Research Tool for Astronomy:
- SPARTAN: series of astronomy satellites launched/retrieved by space shuttle
- SI: modern metric system
- CGS: metric system variant
- joule (J): SI unit of energy
- kelvin (K): temperature scale starting at absolute zero
- magnetic flux (Φ): total magnetism passing through a surface
- magnetic flux density (B): vector field describing magnetism in relation to the Lorentz force
- mole (mol): unit roughly the count of hydrogen atoms in a gram
- siemens (S): SI unit of electrical conductance
- silicon (Si): metal, Si, atomic number 14
- sulfur (S): metal, S, atomic number 16
- tesla (T): unit of magnetic flux density
- watt (W): SI unit of power
- SID:
- side lobe:
- beam: portion of a sky that a radio telescope is viewing
- sidereal: relative to the fixed position of the stars
- sidereal day:
- sidereal: relative to the fixed position of the stars
- solar time: time based upon the position of the Sun in the Earth's sky
- sidereal month:
- sidereal: relative to the fixed position of the stars
- sidereal period:
- orbital period: length of time for an orbiting object to complete one cycle
- synodic period: period until a planet returns to the same position relative to the Sun
- sidereal time:
- solar time: time based upon the position of the Sun in the Earth's sky
- sidereal year:
- sidereal: relative to the fixed position of the stars
- siderophile: material that dissolves in molten iron
- siderophile element:
- Siding Spring Observatory (SSO): observatory in New South Wales, Australia
- siemens (S): SI unit of electrical conductance
- siemens per meter:
- siemens (S): SI unit of electrical conductance
- SIFS:
- SOAR: 4.1 m reflector telescope in Chile
- SIGMA:
- GRANAT: observatory-satellite for detecting gamma rays and X-rays
- sigma (σ): indication of the confidence level of an experiment
- signal:
- signal-to-noise:
- signal-to-noise ratio (SNR,S/N): ratio of the power of a signal to the power of the background noise
- signature:
- spectral signature: spectral characteristics indicating the emitting material and conditions
- signatures of formation: qualities of a body that suggest how it was formed
- SII:
- sulfur (S): metal, S, atomic number 16
- silica:
- basalt: an igneous rock type that shows rapid cooling
- geochemistry: the chemistry of the Earth, planets, and moons
- silicate: type of compound including silicon and oxygen
- silicon (Si): metal, Si, atomic number 14
- silicon burning: alpha process fusion starting at silicon
- silicon dioxide:
- silicon-burning shell:
- Silk damping:
- Silver Coin Galaxy:
- NGC 253: spiral galaxy 11 million light-years away
- Silver Dollar Galaxy:
- NGC 253: spiral galaxy 11 million light-years away
- SIMBAD: online database of astronomical objects
- Simons Array:
- Simons Observatory (SO): CMB observatory on Atacama Desert
- SIMP: 2000s infrared proper-motion survey
- SIMPLE:
- simple Bouguer correction:
- Bouguer anomaly: effect of terrain on gravity measurement on a planet's surface
- simple Bouguer reduction:
- Bouguer anomaly: effect of terrain on gravity measurement on a planet's surface
- simple stellar population:
- SSP: set of stars born at the same time with the same metallicity
- SIMSTACK: software to correlate intensity maps with sources
- simulation:
- AREPO: cosmology simulation using moving mesh technique
- AstroBEAR: MHD simulation system
- Bolshoi simulation: cosmological simulation
- Castro: hydrodynamics simulation software
- Cloudy: code to model the effect of gas and plasma on spectra
- EAGLE: simulation of galaxy formation and evolution
- Enzo: hydrodynamic simulation system
- FIRE Simulations: high resolution simulation of galaxies
- FLASH: hydrodynamic simulation system
- FORNAX: hydrodynamics simulation software
- GADGET-2: an n-body/SPH simulation computer program
- GERLUMPH: hardware/software simulator of lensing light curves
- GR1D: core collapse supernova simulation in 1D with GR
- Hyperion: Monte Carlo radiative transfer code
- Illustris Project: 2013-2015 series of cosmological simulations
- PLUTO Code: fluid-dynamic simulation code
- PROMETHEUS/VERTEX: hydrodynamic simulation system
- RAMSES: hydrodynamic simulation system
- RHAPSODY: simulation of galaxy cluster dark-matter halos
- STARBURST99: software to simulate star-forming galaxies
- Turtlebeach: radiative transfer code
- simulations:
- simultaneity:
- relativity: physics models accommodating the constancy of the speed of light
- SINFONI:
- SINGG:
- single stellar population:
- SSP: set of stars born at the same time with the same metallicity
- single-line spectroscopic binary:
- single-metallicity stellar population:
- SSP: set of stars born at the same time with the same metallicity
- single-object slitless spectroscopy:
- single-photon avalanche diode:
- singly ionized carbon:
- C+: ionized carbon missing one electron
- SINGS:
- singular perturbation problem:
- singularity:
- SINS: near-infrared study of distant luminous galaxies
- SINS/zC-SINF:
- SINS: near-infrared study of distant luminous galaxies
- Sinstro:
- SIPS:
- SIR:
- SMART-1: Swedish lunary orbiter operational 2004-2008
- Sirius: brightest star in the sky
- Sirius A:
- Sirius: brightest star in the sky
- Sirius B:
- Sirius: brightest star in the sky
- SIRTF:
- SIS:
- site:
- arXiv.org: website with physics paper preprints
- Astrophysics Data System (ADS): website with astrophysics bibliography and paper archive
- ExoFOP: site to facilitate exoplanet follow-up observation
- Galaxy Zoo: crowdsourcing website to identify galaxy types from surveys
- Galaxy Zoo 2 (GZ2): crowd-sourced classification of hundreds of thousands of galaxies
- HEASARC: archive of NASA data on high energy astronomy
- IRSA: archive center for infrared data from NASA missions
- LAMBDA: NASA archive center re CMB data
- MAST: archive of data from surveys and missions
- NASA/IPAC Extragalactic Database (NED): a database of galaxies and other objects outside the Milky Way
- Planet Hunters (PH): crowdsourcing website to identify galaxy types from surveys
- SIMBAD: online database of astronomical objects
- SITELLE:
- Sk:
- SKA:
- SKA1:
- SKA1-low:
- SKA1-mid:
- SKA2:
- SKBO:
- skeleton:
- filament: linear volume of high molecular gas density within a galaxy
- SKHB: survey of globular clusters in M31
- Skumanich law:
- Skumanich relationship:
- sky:
- sky subtraction: removing background radiation from a telescope observation
- SkyMapper: automated 1.35 m optical telescope in Australia
- SkyMapper Southern Sky Survey:
- SkyMapper Southern Survey (SMSS): digital survey of the southern hemisphere sky
- SL:
- SLED:
- Slepian window function:
- slew: rotating a telescope to point it
- slew survey: survey conducted by imaging during a telescope's repointings
- slew observation:
- slew survey: survey conducted by imaging during a telescope's repointings
- slew survey: survey conducted by imaging during a telescope's repointings
- commensal mode: telescope usage that accomplishes multiple observations simultaneously
- SLF:
- slide rule:
- slit:
- slitless spectrograph:
- slitless spectroscopy:
- Sloan 2.5m Telescope: telescope for SDSS in New Mexico
- Sloan Digital Sky Survey (SDSS): imaging survey of 500,000,000 objects in 35% of sky
- Sloan Extended Quasar, ELG, and LRG Survey:
- Sloan Extension for Galactic Understanding and Exploration:
- Sloan Foundation 2.5m Telescope:
- Sloan Great Wall (SGW): large slab of galaxies discovered in SDSS
- Sloan Supernova Survey:
- SLOTIS:
- slow irregular variable:
- slow neutron-capture process:
- s-process: synthesization of elements through neutron capture and beta decay
- slow quenching:
- slow shock:
- shock wave: abrupt propagating disturbance in a fluid
- SLS:
- SLSN:
- SLSN-I:
- SLSN-II:
- SLSN-R:
- SM:
- SM0313:
- SMA:
- Small Aperture Telescope:
- Small Astronomical Satellite 1:
- Uhuru: 1970 satellite X-ray telescope
- Small Explorer Program:
- Small Explorers:
- NASA: includes space-based astronomy research
- Small Magellanic Cloud (SMC): dwarf galaxy in the Local Group
- Small Missions for Advanced Research in Technology-1:
- SMART-1: Swedish lunary orbiter operational 2004-2008
- small solar system body:
- minor planet: lesser solar system body without comet characteristics
- SSSB: solar system body smaller than a dwarf planet
- Small-class Explorers Program:
- NASA: includes space-based astronomy research
- SMART-1: Swedish lunary orbiter operational 2004-2008
- SMBBH:
- SMBH:
- SMBH binary:
- binary SMBH (BSMBH,SMBBH,SMBHB): co-orbiting supermassive black holes
- SMBHB:
- binary SMBH (BSMBH,SMBBH,SMBHB): co-orbiting supermassive black holes
- SMC:
- Smethells:
- SMEX:
- SMG:
- SMI:
- SPICA: plan for a future space IR telescope
- SMI-HRS:
- SPICA: plan for a future space IR telescope
- SMI-LRS:
- SPICA: plan for a future space IR telescope
- SMI-MRS:
- SPICA: plan for a future space IR telescope
- Smith Cloud: high-velocity cloud on collision course with Milky Way
- Smith's Cloud:
- Smith Cloud: high-velocity cloud on collision course with Milky Way
- Smithsonian Astrophysical Observatory:
- Smithsonian Astrophysical Observatory Star Catalog:
- Smithsonian Institute:
- SMM:
- SMNS:
- smooth migration:
- smoothed-particle hydrodynamics (SPH): computational method for simulating fluid flows
- SMS:
- SMSS:
- SMT:
- smuon:
- supersymmetry (SUSY): extension to standard model of particle physics
- SN:
- signal-to-noise ratio (SNR,S/N): ratio of the power of a signal to the power of the background noise
- supernova (SN): stellar explosion larger than a nova
- SN 1972E:
- SN 2014J: type Ia supernova in Messier 82, the Cigar Galaxy
- SN 1987A (1987A): supernova in February 1987 rare for being visible by the naked eye
- SN 2011fe:
- SN 2014DJ:
- SN 2014J: type Ia supernova in Messier 82, the Cigar Galaxy
- SN 2014J: type Ia supernova in Messier 82, the Cigar Galaxy
- SN feedback:
- SN Hubble diagram:
- SN impostor:
- SN1054:
- SNAP:
- SNDM:
- Snell's law: optical principle of refraction
- Snell-Descartes law:
- sneutrino:
- supersymmetry (SUSY): extension to standard model of particle physics
- SNEWS:
- SNF:
- SNfactory:
- SNLS:
- snow line: distance from protostar cool enough for water to condense
- snowplow phase:
- SNR:
- SNT:
- SNU:
- SO:
- SOAR: 4.1 m reflector telescope in Chile
- Sobolev approximation: tractable model used in specific kinds of spectral line analysis
- Sobolev length:
- SODART:
- Spektr-RG (SRG, SXG): Russian-German X-ray observatory launched in 2019
- sodium (Na): metal, Na, atomic number 11
- globular cluster (GC): spherical group of stars orbiting a galaxy
- nitrite (NO2-): ion of a nitrogen atom and two oxygen atoms with extra electron
- SOFI:
- SOFIA: aircraft-based infrared observatory
- soft:
- hardness: measure of the binding energy of a binary
- Heggie-Hills law: hard binary stars generally get harder when encountering a third star
- soft binary:
- hardness: measure of the binding energy of a binary
- soft EoS:
- soft gamma repeater (SGR): object that produces repeated gamma ray bursts
- soft X-ray:
- X-ray: electromagnetic radiation, wavelength 0.01 to 10 nanometers
- XEUV: electromagnetic radiation in the range of 0.15-400 nm
- soft X-ray, extreme ultraviolet and ultraviolet:
- XEUV: electromagnetic radiation in the range of 0.15-400 nm
- softness:
- hardness: measure of the binding energy of a binary
- software:
- AREPO: cosmology simulation using moving mesh technique
- AstroBEAR: MHD simulation system
- Astrocats: software to create and manage an astronomy catalog
- Astronomical Image Processing System (AIPS): software for processing radio astronomy data
- ATLAS Stellar Model: computer model of a stellar photosphere
- Bolshoi simulation: cosmological simulation
- BT-Settl: model atmosphere of small stars and brown dwarfs
- Castro: hydrodynamics simulation software
- CMBFAST: software to calculate CMB anisotropies
- code: astrophysical modeling computer program
- DISORT: simulation of radiative transfer in an atmosphere
- EAGLE: simulation of galaxy formation and evolution
- Enzo: hydrodynamic simulation system
- ExoCTK: collection of software for exoplanet observation and analysis
- FIRE Simulations: high resolution simulation of galaxies
- FLASH: hydrodynamic simulation system
- FORNAX: hydrodynamics simulation software
- GADGET-2: an n-body/SPH simulation computer program
- Glue: visualization software good for astrophysical data
- GR1D: core collapse supernova simulation in 1D with GR
- Hyperion: Monte Carlo radiative transfer code
- IDL: interactive vector-oriented programming language
- LasDamas: simulations of large scale evolution of dark matter and galaxies
- lightkurve: software to analyze time series data
- MITgcm: well-known general circulation model
- OpenSpace: visualization software aimed at astrophysical data
- Partiview: visualization software aimed at 4D data
- PHOENIX stellar model: computer model of a stellar photosphere
- PLUTO Code: fluid-dynamic simulation code
- PROMETHEUS/VERTEX: hydrodynamic simulation system
- RAMSES: hydrodynamic simulation system
- RHAPSODY: simulation of galaxy cluster dark-matter halos
- ROCKE-3D: Rocky-planet-oriented general circulation model
- SIMSTACK: software to correlate intensity maps with sources
- SPECTRE: an interactive spectrum analysis software package
- STARBURST99: software to simulate star-forming galaxies
- StarTrack: stellar population synthesis code
- TAM: non-gray-RT 3D model of Titan's atmosphere
- Turtlebeach: radiative transfer code
- Uniview: planetarium software
- yt: analysis and display software
- software telescope: telescope that depends more than normal upon software for analysis
- software type:
- SOHO:
- SOI:
- SOAR: 4.1 m reflector telescope in Chile
- Sojourner:
- Sol:
- Mars: well-explored planet in the solar system
- solar:
- Solar and Heliospheric Observatory (SOHO): satellite observing the Sun
- solar antapex:
- solar apex: direction that the Sun is moving compared to nearby stars
- solar apex: direction that the Sun is moving compared to nearby stars
- solar arcade:
- solar cell:
- photodiode: class of solid state device to detect EMR
- solar circle: Sun's orbit around the Milky Way
- solar constant: flux from the Sun at 1 AU
- solar core:
- solar cycle:
- dynamo: mechanism for generating magnetic fields around astronomical bodies
- sunspot: temporary darker region of the Sun's surface
- solar day:
- Venus: second inner-most planet in the solar system
- Solar Dynamics Observatory (SDO): 2010 satellite observing the Sun
- solar dynamo:
- dynamo: mechanism for generating magnetic fields around astronomical bodies
- solar energetic particle (SEP): high-energy particles from the Sun
- solar eruption: sudden brightening of the Sun
- solar event:
- solar flare: sudden brightening of the Sun
- solar galactocentric distance:
- solar irradiance:
- insolation: solar energy received per unit area in given time
- solar lithium problem:
- solar luminosities:
- watt (W): SI unit of power
- solar luminosity:
- Sun: star at center of solar system
- watt (W): SI unit of power
- solar mass (MSun,Msun): mass unit representing the mass of the Sun
- mass: object's quality that determines the effects of forces and gravity
- Sun: star at center of solar system
- solar maximum:
- sunspot: temporary darker region of the Sun's surface
- Solar Maximum Mission (SMM): 1980s satellite to study the Sun during solar maximum
- solar minimum:
- magnetic field: magnetic force as distributed over a space
- sunspot: temporary darker region of the Sun's surface
- solar model:
- solar motion:
- solar apex: direction that the Sun is moving compared to nearby stars
- solar nebula: cloud of gas and dust that formed the solar system
- solar nebular disk model:
- solar neighborhood: Milky Way in the vicinity of the Sun
- solar neutrino problem:
- solar neutrino unit (SNU): unit for the detection rate of neutrino detectors
- solar noon:
- equinox: times when tilt of Earth is neither toward or away from the Sun
- solar time: time based upon the position of the Sun in the Earth's sky
- Solar Orbiter (SolO): Sun-observing satellite in development
- solar particle event (SPE): episode of higher velocity solar wind
- solar physics: study of the physics of the Sun
- solar prominence:
- solar prominence coronal loop:
- solar proton event:
- solar radius:
- Sun: star at center of solar system
- solar seismology:
- solar storm: general term for events on the Sun
- Solar Storm of 1859:
- solar system: the Sun and what's gravitationally bound to it
- anomalous cosmic rays (ACR): cosmic rays with unexpectedly low energies
- asteroid: minor planet without comet characteristics
- asteroid belt: ring of orbiting planetoids/asteroids
- asteroid family: set of asteroids based on similar orbits
- binary minor planet (BMP): minor planet with another body orbiting it
- CAI: calcium/aluminum specs in chondrites
- centaur: asteroid-like body orbiting among the outer planets
- chondrite: stony meteorites showing no melting
- comet: Sun-orbiting object with coma and possible tail
- damocloid: minor planet with a comet-like orbit
- dwarf planet: round like a planet, only smaller
- Earth: third solar system planet from the Sun
- ephemeris: information on the position of a celestial body in the sky over time
- equilibrium condensation model: chemical model explaining solar system planet abundances
- heliopause: boundary between solar wind and the interstellar medium
- heliosheath: region just beyond the heliosphere
- Hills cloud: cloud of comets and minor planets around the solar system
- interplanetary medium (IPM): matter in the solar system around and between planets
- irregular moon: moon with an atypical orbit, such as retrograde
- Jupiter: largest planet in the solar system
- Kuiper Belt (K Belt,KB): further part of solar system beyond Neptune
- late heavy bombardment (LHB): time after solar system planet-formation when many impacts occurred
- long-period comet: comet with an orbital period of more than 200 years
- Mars: well-explored planet in the solar system
- Mercury: inner-most and smallest planet in the solar system
- meteoroid: rocky object in solar system, smaller than an asteroid
- minor planet: lesser solar system body without comet characteristics
- near-Earth object (NEO): object orbiting the Sun that passes close to Earth
- nebular hypothesis: model positing solar system planets result from a solar disk
- Neptune: outer-most solar system planet
- Nice model: model of the evolution of the solar system
- oligarch: term for large planetesimals that dominate
- Oort Cloud: cloud of comets and minor planets around the solar system
- orrery: mechanical device to simulate the solar system
- Outer Solar System Origins Survey (OSSOS): survey searching for trans-Neptune objects
- planet: round object orbiting a star that clears out its own orbital path
- Planet Nine: theoretical planet beyond Neptune
- planetoid: an asteroid or physically similar body
- plutoid: Pluto-like dwarf planet
- provisional designation: way to designate newly discovered solar system objects
- Saturn: second largest planet in the solar system
- solar constant: flux from the Sun at 1 AU
- solar nebula: cloud of gas and dust that formed the solar system
- solar neighborhood: Milky Way in the vicinity of the Sun
- solar wind: charged particles emanating from the Sun
- SPACEWATCH: survey to study minor planets
- SSSB: solar system body smaller than a dwarf planet
- star system: a gravitationally bound set of a few stars
- Sun: star at center of solar system
- trans-Neptunian object (TNO): minor planet beyond Neptune
- Uranus: second outer-most solar system planet
- Venus: second inner-most planet in the solar system
- Voyager: space probes to observe planets and the edge of the solar system
- solar system ephemerides:
- ephemeris: information on the position of a celestial body in the sky over time
- solar telescope: telescope designed to observe the Sun
- Solar Terrestrial Relations Observatory:
- STEREO: two-satellite system to observe the Sun
- solar time: time based upon the position of the Sun in the Earth's sky
- solar transition region:
- solar variation:
- sunspot: temporary darker region of the Sun's surface
- solar weather:
- solar wind: charged particles emanating from the Sun
- SOLAR-A:
- Solar-flux monitor:
- solar-like oscillations:
- solid angle (Ω): two-dimensional analog of an angle
- field of view (FOV): angular measure of how much an optical instrument can view
- solid state detector:
- SolO:
- SoloHI:
- SOLSTICE:
- Soltan argument: distant quasars imply SMBHs still exist
- Sombrero Galaxy (M104): striking spiral galaxy with very large bulge
- Sondage Infrarouge de Mouvement Propre:
- SIMP: 2000s infrared proper-motion survey
- sonic Mach number:
- SOSS:
- sound:
- sound speed: speed at which compression waves traverse a gas
- sounder: device to measure something at another depth
- sound horizon:
- sound speed: speed at which compression waves traverse a gas
- sounder: device to measure something at another depth
- sounding:
- sounder: device to measure something at another depth
- sounding rocket:
- sounder: device to measure something at another depth
- source:
- radio source (RS): something in the sky generating radio signal
- source confusion:
- confusion limit: limit on telescope imaging due to too many sources in the same region
- source counts:
- source function (S): measure indicating the effect of a material on EMR passing through
- South Africa:
- South African Astronomical Observatory (SAAO): South African observatory with SALT telescope
- south node:
- South Pole:
- ACBAR: instrument used in CMB search
- BICEP2: survey to measure the polarization of the CMB
- CMB Stage-4 (CMB-S4): planned 2020s-generation of ground CMB observations
- DASI: 2000-2003 South Pole CMB telescope
- IceCube: neutrino detector at the South Pole
- South Pole Telescope (SPT): a microwave to radio telescope at South Pole
- South Pole Station:
- BICEP2: survey to measure the polarization of the CMB
- South Pole Telescope (SPT): a microwave to radio telescope at South Pole
- Southern African Large Telescope (SALT): 10 meter telescope in South Africa
- Southern Astrophysical Research Telescope:
- Southern Great Wall:
- Southern Sky Atlas:
- Southern Sky Survey:
- Southern Supercluster:
- Southern Wall:
- southern zone of avoidance:
- SP77:
- space:
- Space Infrared Telescope Facility:
- Space Infrared Telescope for Cosmology and Astrophysics:
- SPICA: plan for a future space IR telescope
- Space Launch System (SLS): launch rocket in development, e.g., for future astronomical projects
- Space Shuttle:
- Space Surveillance Telescope:
- LINEAR: survey of near-Earth objects
- Space Telescope Science Institute (STScI): science operator of space telescopes
- space weather: varying conditions in space affecting Earth and humans
- space weathering:
- weathering: changes in surface due to contact with atmosphere
- space-like:
- geodesic: equivalent to a straight line in curved space
- spacetime diagram: graph of simplified spacetime, with fewer space dimensions
- spacecraft:
- Spacelab:
- spacetime: four dimensions: time and the three space dimensions
- curvature: unflatness of space
- geodesic: equivalent to a straight line in curved space
- worldline: path of an object through space and time
- spacetime diagram: graph of simplified spacetime, with fewer space dimensions
- spacetime interval:
- SPACEWATCH: survey to study minor planets
- Spacewatch 1.8-m telescope:
- SPAD:
- SPADUS:
- ARGOS: 1999 technology-research satellite
- spaghettification:
- tidal force: effect of a third body on the gravitational force between two bodies
- Spain:
- SPARC:
- MITgcm: well-known general circulation model
- SPARC/MITgcm:
- MITgcm: well-known general circulation model
- spark chamber: type of ion detector
- SPARSEPAK:
- SPARTAN: series of astronomy satellites launched/retrieved by space shuttle
- SOAR: 4.1 m reflector telescope in Chile
- SPARTAN-201:
- SPARTAN: series of astronomy satellites launched/retrieved by space shuttle
- spatial correlation function:
- spatial direction:
- spatial frequency:
- spatial resolution:
- SPD:
- SPE:
- SpEC: code to solve general relativity problems
- special relativity:
- Lorentz transformation: equations describing the effect of relative motion on length and velocity
- mass: object's quality that determines the effects of forces and gravity
- redshift (z): change to longer wavelengths due to Doppler effects
- relativity: physics models accommodating the constancy of the speed of light
- spacetime: four dimensions: time and the three space dimensions
- worldline: path of an object through space and time
- specific angular momentum (J): absolute angular momentum divided by mass
- specific heat: ratio of added temperature to added heat for a material
- specific heat capacity:
- specific heat: ratio of added temperature to added heat for a material
- specific humidity:
- humidity: amount of water vapor in a portion of the atmosphere
- specific intensity: intensity per unit wavelength or frequency
- brightness temperature (TB): temperature of an equivalent black body in terms of intensity
- flux density: measure of the strength of a radio signal
- intensity: power reaching a surface from a specific source
- radiance: measure of EMR to/from a solid angle through and area
- specific star formation rate:
- specific volume: ratio of volume to mass
- specification:
- angular resolution: measure of a telescope's ability to distinguish spatial detail
- cadence: period between observations
- elevation range: measure of how high and low a telescope can be pointed
- emissivity: measure of a material's efficiency at radiating thermal radiation
- exit pupil: size of the image as presented to the eye
- field of view (FOV): angular measure of how much an optical instrument can view
- Fsky (fsky): fraction of the sky, e.g., what a survey covers
- pointing error (PE): discrepancy in telescope's aim
- scan speed: the speed at which the telescope changes angle on the sky while observing
- sensitivity function (S): function of wavelength giving the sensitivity of an instrument
- spectral resolution: measure of a spectrograph's ability to resolve features of the spectrum
- Strehl ratio: measure of optical aberration
- wavefront error (WFE): measure of a telescope's distortion of incoming waves
- speckle noise:
- speckle suppression: methods of reducing noise in telescope observations
- spectral band: set of related, closely-packed spectral lines
- spectral brightness:
- flux density: measure of the strength of a radio signal
- radiance: measure of EMR to/from a solid angle through and area
- spectral class: overall classification of stars based upon spectral features
- A-type star (A): star with spectral characteristics of around 8500 K
- B-type star (B): star with spectral characteristics of around 10000-30000 K
- carbon star (C): star with more carbon than oxygen in its atmosphere
- F-type star (F): spectral class of star a bit hotter than then Sun
- G-type star (G): stars spectrally similar to the Sun
- K-type star (K): spectral class of star a bit cooler than the Sun
- L-type star (L): spectral type of star cooler than an M-type star
- M-type star (M): spectral class of star with a temperature in the vicinity of 2500 K
- O-type star (O): star with spectral characteristics of above 30000 K
- S-type star (S): type of star with lines indicating zirconium
- T-type star (T): brown dwarf with a temperature in the vicinity of 1000 K
- Y-type star (Y): brown dwarf with a temperature less than 700 K
- spectral classification:
- spectral class: overall classification of stars based upon spectral features
- spectral correlator: correlator that also functions as a spectrograph
- spectral density: strength of power or energy as a function of frequency
- spectral differential imaging:
- spectral direction:
- Spectral Einstein Code:
- SpEC: code to solve general relativity problems
- spectral emissivity:
- emissivity: measure of a material's efficiency at radiating thermal radiation
- spectral energy distribution (SED): function or plot of brightness at each wavelength in the spectrum
- spectral energy distribution fitting:
- spectral feature: recognizable feature of a spectrum
- spectral feature extraction:
- spectral flux:
- 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 intensity:
- spectral irradiance:
- spectral line: dark or light line in a spectrum
- spectral line designation: labels used to identify spectral lines
- spectral line energy distribution (SLED): function or plot of brightness of lines in a spectrum
- spectral line index:
- Lick indices: defined set of spectral line indexes for stars
- spectral line shape:
- spectral method: method of numerically solving differential equations
- spectral photometry:
- photometry: studying starlight through bandpass filters
- spectral photon distribution:
- spectral power distribution (SPD): function of power versus wavelength or frequency
- spectral radial velocity:
- spectral radiance:
- intensity: power reaching a surface from a specific source
- radiance: measure of EMR to/from a solid angle through and area
- radiative transfer (RT): energy transfer in the form of electromagnetic radiation
- specific intensity: intensity per unit wavelength or frequency
- spectral resolution: measure of a spectrograph's ability to resolve features of the spectrum
- spectral retrieval:
- retrieval: determining measures through observation and modeling
- spectral signature: spectral characteristics indicating the emitting material and conditions
- spectral type: classification of stars based upon spectral features
- spectral class: overall classification of stars based upon spectral features
- spectral-line mapping:
- SPECTRE: an interactive spectrum analysis software package
- IRTF: Mauna Kea 3-meter infrared telescope
- Spectro-photometer for the History of the Universe, Epoch of Reionization, and Ices Explorer:
- SPHEREx: all-sky spectral survey space-mission plan
- Spectro-polarimetric High-contrast Exoplanet Research:
- SPHERE: VLT instrument for imaging exoplanets
- spectro-z:
- 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
- spectrometers:
- spectrometry: measuring the strengths of different electromagnetic wavelengths
- Spectropolarimètre infrarouge:
- SPIRou: CFHT spectropolarimeter for exoplanet research
- spectropolarimeter:
- Spectropolarimeter for Planetary Exploration:
- SpeX: a medium-resolution infrared spectrograph
- spectropolarimetry: measurement of light's polarization by wavelength
- spectroscope: device to study the spectrum of incoming light
- 4MOST: spectrograph in development for VISTA telescope
- spectrograph: device to record the spectrum of incoming light
- spectrometer: device to measure light by wavelength across its spectrum
- spectroscopy: measurement of light with various electromagnetic wavelengths
- STARFIRE: planned balloon-borne 2.5 m telescope and spectroscope
- spectroscopic binary (SB): binary star detected by movement indicated by Doppler shifts in the spectrum
- Spectroscopic Imaging Survey in the Near-infrared with SINFONI:
- SINS: near-infrared study of distant luminous galaxies
- spectroscopic parallax: stellar distance determined through spectroscopy
- spectroscopic phase curve:
- phase curve: brightness of an object according to its phase angle
- Spectroscopic Properties of Cool Stars (SPOCS): analysis of spectroscopic data of 7000+ M and L stars
- spectroscopic redshift:
- spectroscopic retrieval:
- retrieval: determining measures through observation and modeling
- Spectroscopic Survey Telescope:
- Spectroscopic Terahertz Airborne Receiver for Far-infrared Exploration:
- STARFIRE: planned balloon-borne 2.5 m telescope and spectroscope
- spectroscopy: measurement of light with various electromagnetic wavelengths
- spectrograph: device to record the spectrum of incoming light
- spectrometer: device to measure light by wavelength across its spectrum
- spectroscope: device to study the spectrum of incoming light
- spectrum:
- absorption line: dark line in a spectrum
- Balmer jump: abrupt change in stellar spectrum at end of Balmer series
- Balmer series (H): hydrogen lines for electrons settling from n > 2 to n = 2
- Brackett series: hydrogen lines for electrons settling from n > 4 to n = 4
- continuous absorption: the absorption of a whole section of a spectrum
- continuous spectrum: smooth spectrum or portion of spectrum with no lines
- emission line: narrow frequency-region of a spectrum with higher intensity
- extreme ultraviolet (EUV,XUV): electromagnetic radiation in the range of 10-124 nm
- extremely low frequency (ELF): electromagnetic radiation, frequency 3 Hz to 30 Hz
- far infrared (FIR,far-IR): infrared radiation with wavelengths in the 30-450 μm range
- gamma rays (GR): electromagnetic radiation, wavelength 10 picometers and less
- H-alpha (Ha,Hα, H-α): hydrogen line for electrons settling from n = 3 to n = 2
- high frequency (HF): electromagnetic radiation, frequency 3-30 MHz
- infrared (IR): electromagnetic radiation, wavelength 0.74-300 micrometers
- integral field unit (IFU): instrument to allow a spectrograph to capture data over a 2D field
- K-line: iron X-ray line
- line blanketing: so many bunched spectral lines that they cannot be distinguished
- line broadening: processes causing a spectral line to have width
- Lyman alpha (Ly-α,Lyα): first line in the Lyman series
- Lyman series (L,Ly): hydrogen series from electrons settling from n > 1 to n = 1
- microwave: electromagnetic radiation, frequency 300 MHz to 300 GHz
- mid infrared (MIR,mid-IR): infrared radiation with wavelengths in the 7.5-25 μm range
- 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
- oxygen lines: spectral lines specific to oxygen
- P Cygni profile: line profile showing both red and blue shifts
- Paschen series: hydrogen lines for electrons settling from n > 3 to n = 3
- radio: electromagnetic radiation, frequency 3kHz to 300GHz
- spectral line: dark or light line in a spectrum
- spectral line designation: labels used to identify spectral lines
- spectral power distribution (SPD): function of power versus wavelength or frequency
- subradio: electromagnetic radiation, frequency below 3 kHz
- super low frequency (SLF): electromagnetic radiation, frequency 30 Hz to 300 Hz
- telluric line: absorption line in ground observation due to Earth atmosphere
- Thermal Bremsstrahlung: type of EMR produced by thin, hot plasma
- tremendously low frequency (TLF): electromagnetic radiation, frequency below 3 Hz
- ultra low frequency (ULF): electromagnetic radiation, frequency 300 Hz to 3 kHz
- 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
- very low frequency (VLF): electromagnetic radiation, frequency 3-30 kHz
- very-high-energy gamma rays (VHEGR): energetic gamma rays with 100 GeV to 100 TeV photon energy
- visible light: electromagnetic radiation, wavelength 390-750 nm
- water lines: spectral lines specific to water
- X-ray: electromagnetic radiation, wavelength 0.01 to 10 nanometers
- XEUV: electromagnetic radiation in the range of 0.15-400 nm
- spectrum analysis:
- SPECTRE: an interactive spectrum analysis software package
- spectrum binary: binary star detectable because its spectrum looks like that of two stars
- spectrum synthesis:
- Cloudy: code to model the effect of gas and plasma on spectra
- Spectrum-Roentgen-Gamma:
- eROSITA: Russian/German space X-ray telescope launched in 2019
- Spectrum-X-Gamma:
- Spektr-RG (SRG, SXG): Russian-German X-ray observatory launched in 2019
- SPECULOOS: search for Earth-like exoplanets orbiting nearby dim stars
- SPECULOOS Southern Observatory:
- SPEDE:
- SMART-1: Swedish lunary orbiter operational 2004-2008
- speed of light (c): fundamental constant measured as the speed at which light travels
- speed of light in a vacuum:
- speed of light (c): fundamental constant measured as the speed at which light travels
- speed of sound:
- sound speed: speed at which compression waves traverse a gas
- SpeedyMC:
- Spektr-R: 10 m space radio telescope
- Spektr-RG (SRG, SXG): Russian-German X-ray observatory launched in 2019
- eROSITA: Russian/German space X-ray telescope launched in 2019
- SpeX: a medium-resolution infrared spectrograph
- IRTF: Mauna Kea 3-meter infrared telescope
- SPF:
- SPH:
- SPHERE: VLT instrument for imaging exoplanets
- SPHEREx: all-sky spectral survey space-mission plan
- spherical aberration: mis-focusing by spherically-curved mirrors and lenses
- spherical astronomy:
- astrometry: precise measurement of the position and movement of stars
- spherical cow:
- spherical galaxy:
- galaxy: gravitationally-bound group of stars
- spherical harmonic order:
- spherical harmonics: harmonic functions on the surface of a sphere
- spherical shell:
- spheroidal:
- SPI:
- INTEGRAL: European gamma ray observatory-satellite
- SPICA: plan for a future space IR telescope
- SPICAM:
- SPICE:
- spicule: small temporary jet from Sun's surface
- SPIDER: 2015 airborne observatory to observe CMB polarization
- spin (ms): an angular-momentum quantum number
- spin quantum number:
- spin-down luminosity: pulsar's energy extracted from slowing rotation
- spin-down time:
- spin-down timescale:
- Spindle Galaxy (NGC 5866): striking spiral galaxy with very large bulge
- spinel:
- CAI: calcium/aluminum specs in chondrites
- spinning dust:
- spinning dust emission: source of microwave signal
- spiral:
- spiral arm: long, winding visible structure within a spiral galaxy
- spiral density wave: spiral structure that can form in disks
- spiral galaxies:
- spiral galaxy: flat galaxy with spiraling arms
- spiral nebula:
- Kapteyn universe: early 20th century model of the universe centered on the Milky Way
- spiral structure:
- SPIRE:
- Spirit:
- SPIRIT III:
- SPIRITS: Spitzer survey designed to find transients
- SPIRou: CFHT spectropolarimeter for exoplanet research
- Spitzer:
- Spitzer Extended Deep Survey (SEDS): survey of galaxy mass and black holes through life of the universe
- Spitzer Extragalactic Representative Volume Survey (SERVS): infrared survey of some well-studied fields
- Spitzer HETDEX Exploratory Large Area Survey (SHELA): Spitzer-based survey of galaxies
- Spitzer Infrared Intensive Transient Survey:
- SPIRITS: Spitzer survey designed to find transients
- Spitzer Space Telescope (SST): past a satellite with infrared telescope
- Spitzer Warm Mission:
- splashback:
- splashback radius:
- SPOCS:
- SPOL:
- MMT: 6.5 meter telescope at Mt. Hopkins, Arizona
- spontaneous emission:
- emission: addition of photons to a beam of EMR
- spontaneous symmetry breaking:
- symmetry breaking: loss of symmetry, such as due to loss of stability in a regime change
- Sprite:
- Starshot: plan for mission to fly by Alpha Centauri
- SPS:
- SPS code:
- SPT:
- SPT-CL:
- SPT-SZ:
- SPTpol:
- SQM:
- neutron star (NS): stellar remnant consisting entirely of solar masses of neutrons
- square degree:
- Square Kilometre Array (SKA): radio telescope collecting a square kilometer
- square radian:
- squark:
- supersymmetry (SUSY): extension to standard model of particle physics
- SR:
- SRG:
- eROSITA: Russian/German space X-ray telescope launched in 2019
- Spektr-RG (SRG, SXG): Russian-German X-ray observatory launched in 2019
- SRR:
- MDR/SRR: planning step for a NASA mission
- SRT:
- SS:
- SS 433: first microquasar discovered
- SSC:
- Stardust: space mission that collected and returned comet coma dust
- synchrotron self-Compton (SSC): charged particle cloud scattering its own synchrotron-produced photons
- SSD:
- SSE:
- ephemeris: information on the position of a celestial body in the sky over time
- SSFR:
- SSI:
- Ariel 5: 1970s X-ray space telescope
- Galileo: circa 1990s space mission to Jupiter
- Phoenix: Mars polar-region probe launched by NASA in 2007 with lander
- SSM:
- SSO:
- SSP: set of stars born at the same time with the same metallicity
- Cassini: explorer spacecraft sent to Saturn
- SSS:
- SSSB: solar system body smaller than a dwarf planet
- minor planet: lesser solar system body without comet characteristics
- SSSPM:
- SST:
- St:
- Stokes number (Stk,St): measure of a particle's tendency to flow the flow of a fluid
- Stömgren radius:
- stability radius:
- isolation mass: mass of an oligarch after accreting all nearby planetesimals
- stable isotope:
- isotope: subclass of an element with a specific number of nucleons
- stacking: combining images of the same object
- standard atomic weight:
- element: class of atom based on its number of protons
- standard Big Bang:
- Big Bang: theoretical event when the universe expanded from a point
- standard candle: astronomical object whose brightness can be determined
- standard deviation:
- error bar: feature of a graph to indicate accuracy
- RMS: square root of the average of some squared values
- sigma (σ): indication of the confidence level of an experiment
- velocity dispersion (σ): statistical dispersion of velocities of a group of objects
- standard error of the mean:
- error bar: feature of a graph to indicate accuracy
- standard gravitational parameter (μ): a body's mass times the gravitational constant
- standard main sequence:
- standard model: model of elementary particles including quarks
- Lambda-CDM model (ΛCDM,LCDM): Big-Bang cosmological model with a cosmological constant and cold dark matter
- quark: type of elementary particle incorporated in protons and neutrons
- standard model of a flare: description of how solar flares function
- standard model of particle physics:
- axion (A0): proposed light, electrically neutral elementary particle
- standard model: model of elementary particles including quarks
- supersymmetry (SUSY): extension to standard model of particle physics
- standard reduction potential:
- standard ruler: astronomical phenomenon whose size can be determined
- standard siren: transient whose gravitational waves indicate a specific distance
- standard solar model:
- standard source:
- photometry: studying starlight through bandpass filters
- standard star:
- Stanford University:
- Kavli Institute: any of a number of science institutes supported by Kavli Foundation
- star:
- star and planet formation:
- star catalog:
- astrometry: precise measurement of the position and movement of stars
- astronomical catalog: lists of observed astronomical bodies and their characteristics
- star catalogue:
- star class:
- star cloud: lighter region of the night sky consisting of a high density of stars
- star cluster:
- star clusters:
- star count: surveys of stars counting them according to some criteria
- star formation (SF): theorized collapse of gas and dust into stars
- star formation efficiency:
- star formation feedback: mechanisms whereby star formation regulates its own rate
- star formation history (SFH): star formation rate as a function of time
- star formation law:
- star formation main sequence:
- star formation rate (SFR): rate at which material such as gas is turned into stars
- star formation rate density:
- star forming filament:
- filament: linear volume of high molecular gas density within a galaxy
- star forming galaxy:
- star forming region:
- star system: a gravitationally bound set of a few stars
- solar system: the Sun and what's gravitationally bound to it
- star type:
- A-type star (A): star with spectral characteristics of around 8500 K
- Am star: A-type star with metallic lines
- anomalous X-ray pulsar (AXP): X-ray pulsars with slow rotation and strong magnetic field
- Ap star: peculiar type of A star
- astrometric binary: binary star system detected by observing the movement of a star
- asymptotic giant branch (AGB): a second stage of helium burning in some stars
- B-type star (B): star with spectral characteristics of around 10000-30000 K
- Be star: early star with Balmer emission lines
- binary neutron star (BNS,NSB,DNS): two neutron stars co-orbiting
- binary star: system of two stars co-orbiting
- blue horizontal branch (BHB): blue end of the horizontal branch
- brown dwarf (BD): star-like object with less mass than a star
- carbon star (C): star with more carbon than oxygen in its atmosphere
- cataclysmic variable star (CV): star whose magnitude is much brighter on occasion
- Cepheid variable (CEP): type of star that varies with a constant period
- chemically peculiar star (CP star): star with SED showing presence metals unusual for stars
- collapsar: neutron star or stellar black hole
- common envelope: binary star system surrounded by a single gas cloud
- compact object (CO): dense astronomical body such as white dwarf or denser
- contact binary: binary stars orbiting so close they are touching
- double star: two stars close together in the sky
- double-line spectroscopic binary (SB2): spectroscopic binary star where a specific line shows up at two different wavelengths
- eclipsing binary (E): binary star system detected by variations in magnitude
- exotic star: term for theoretical stars not made of atoms/ions
- F-type star (F): spectral class of star a bit hotter than then Sun
- failed binary: like a binary star but one not achieve the mass of a star
- FGK star: a star of the "middle" spectral classes, F, G, and K
- field star: star that is not part of a star cluster
- fixed star: star that does not change position in the celestial sphere
- FU Orionis star (FUor): type of variable pre-main-sequence star
- G-type star (G): stars spectrally similar to the Sun
- giant star: star larger than main sequence stars
- high-B radio pulsar (HBRP): pulsar with a strong magnetic field
- high-velocity star: star moving noticeably faster than neighbors
- horizontal branch (HB): a second "giant" stage in the evolution of some main sequence stars
- hypergiant: extremely bright stars
- hypermassive neutron star (HMNS): neutron star massive enough to collapse
- hypervelocity star (HVS,HV): star moving very much faster than usual
- K-type star (K): spectral class of star a bit cooler than the Sun
- L-type star (L): spectral type of star cooler than an M-type star
- Lambda Boötis star (λ Boo): peculiar star with metallicity only with lighter elements
- low mass star (LMS): stars of less than half the solar mass
- luminous blue variable (LBV): type of extremely bright variable stars
- M dwarf: small, cool main-sequence star in stellar class M
- M-type star (M): spectral class of star with a temperature in the vicinity of 2500 K
- magnetar: neutron star with a strong magnetic field
- main sequence star (MS,V): star burning hydrogen into helium in its center
- neutron star (NS): stellar remnant consisting entirely of solar masses of neutrons
- O-type star (O): star with spectral characteristics of above 30000 K
- O5 spectral type (O5): spectral type of star with a temperature of about 45000 K
- OB star: a hot star with class O or early B
- OH/IR source: AGB star with strong OH maser
- optical double: double star where the two are not gravitationally bound
- PG 1159 star: star in transition between planetary nebula and white dwarf
- post-common envelope binary (PCEB): binary star system showing unusual stellar evolution
- post-main-sequence star: star evolved beyond its main sequence phase
- pre-main-sequence star (PMS,pre-MS): star not yet with a nuclear reaction
- pulsar (PSR): type of astronomical body with EMR in regular cycles of seconds or less
- pulsating star: variable star that varies through energy pulses
- radio star: star emitting much radio
- red clump (RC): like horizontal branch but at one temperature
- red dwarf: small, cool main-sequence star
- red giant: very bright red star
- red-giant branch (RGB): an early red-giant phase of post-main-sequence stellar evolution
- RR Lyrae variable (RRL,RR): star with periodic variation often in globular clusters
- S-type star (S): type of star with lines indicating zirconium
- shell star (sh): type of star with broad and narrow absorption lines
- spectroscopic binary (SB): binary star detected by movement indicated by Doppler shifts in the spectrum
- spectrum binary: binary star detectable because its spectrum looks like that of two stars
- stellar remnant: leftovers from a mainstream star
- subdwarf (sd,VI): star less bright than the main sequence given its spectral class
- subgiant: slightly larger than normal star
- substellar object: star-like object with less mass than a star
- supergiant: very large giant star
- supermassive star (SMS): star more massive than stars normally form
- symbiotic binary (SS): giant star transferring mass to a somewhat distant companion
- T-Tauri star (TTS): type of variable pre-main-sequence star
- T-type star (T): brown dwarf with a temperature in the vicinity of 1000 K
- technetium star: star showing technetium absorption lines
- telluric star: star of known spectrum used for calibration
- Thorne-Żytkow object (TZO,TŻO): giant star with a neutron star at its center
- ultracool dwarf: star or brown dwarf cooler than M7 class
- variable star: star that varies in magnitude
- visual binary: binary star system in which both stars can be seen
- weak-line star: star with faint spectral lines compared to its spectral class
- white dwarf (WD): stellar remnant of mostly electron-degenerate matter
- wide binaries (WB): binary stars thousands of AU apart
- Wolf-Rayet star: type of star with broad emission bands
- Y-type star (Y): brown dwarf with a temperature less than 700 K
- young stellar object (YSO): early stage of a star
- star-formation rate stellar-mass ratio: ratio between a galaxy's stellar mass and its SF rate
- star-forming radio galaxy:
- star-forming region (SFR): areas forming stars or ripe for star formation
- STAR-X: concept for a future X-ray space telescope
- starburst:
- AzTEC-3: very distant starburst galaxy
- HFLS3: very distant starburst galaxy
- M82: nearby starburst galaxy
- NGC 253: spiral galaxy 11 million light-years away
- starburst galaxy: galaxy forming stars at a very high rate
- starburst galaxy: galaxy forming stars at a very high rate
- STARBURST99: software to simulate star-forming galaxies
- StarChip:
- Starshot: plan for mission to fly by Alpha Centauri
- Stardust: space mission that collected and returned comet coma dust
- STARE Telescope:
- starfield:
- asterism: easily recognizable star pattern
- STARFIRE: planned balloon-borne 2.5 m telescope and spectroscope
- Stargazer:
- Starlight Attenuation & Reddening Survey of Multiple Occulting Galaxies:
- stars:
- accretion: enlargement of an astronomical body by gravitationally attracting additional mass
- accretion disk: disk around an astronomical body of material that is accreting
- Aitken Double Star Catalogue (ADS): 1932 catalog with both multiple-star systems and non-orbiting double stars
- All-Sky Compiled Catalogue (ASCC,ASCC-2.5): 2001 catalog compiled from modern sources
- APASS: down to 16 magnitude
- asterism: easily recognizable star pattern
- asteroseismology: study of stars through analysis of their pulsation
- Astrographic Catalog (AC): historical star catalog of the whole sky to magnitude 11
- Astronomische Gesellschaft Katalog (AGK): 19th/20th century astrometric catalog
- ATLAS Stellar Model: computer model of a stellar photosphere
- atmosphere: gas surrounding astronomical object
- Balmer jump: abrupt change in stellar spectrum at end of Balmer series
- BATC: photometric survey of Milky Way stars
- Bayer designation: star designation system dating from 1600s
- Bcool: project studying stellar magnetism
- Bibliographic Catalog of Variable Stars (BCVS): listing of references to variable stars
- bipolar outflow: streams of matter from the poles of a protostar
- Bonner Durchmusterung Catalog (BD): well-known astrometric catalog from late 1800s
- Boss General Catalog (GC): 1937 catalog of 30,000 stars
- Bright Star Catalog (HR,BS,YBS): early 20th century catalog of 9000 stars
- Bruce Proper Motion Survey (BPM): 1941 southern-hemisphere survey catalog of Luyten's
- BT-Settl: model atmosphere of small stars and brown dwarfs
- bulge: denser group of stars within a larger group
- Burnham Double Star Catalogue (BDS,BU): 1906 catalog with multiple star systems and non-orbiting double stars
- calcium-rich gap transient: type of explosive event larger than a nova and smaller than a supernova
- California-Kepler Survey (CKS): followup to Kepler to determine stellar radii
- candidate companion (CC): possible object apparently orbiting a known object
- Carlsberg Meridian Catalogue (CMC): series of astrometric catalogs from 19th century on
- Case-Hamburg Survey (LS): 1950s-1970s survey(s) of OB stars
- Catalog of Azzopardi & Vigneau (AzV): probable stars in the SMC
- Catalog of Circumpolar Stars (Groombridge): list of over 4000 stars in northern part of the sky
- Catalog of Components of Double and Multiple Stars (CCDM): 1994 catalog of 74000 such double-star components
- Catalog of Stellar Identifications (CSI): 1970s catalog cross referencing existing star catalogs
- Catalogue of Southern Double Stars: 1955 catalog with multiple star systems and non-orbiting double stars
- Catalogues of Fundamental Stars: series of astrometric catalogs from 19th century on
- CFHTLS: surveys of transients and stars
- Chandrasekhar limit: maximum mass of a white dwarf
- chromosphere: middle layer of the Sun's atmosphere
- chromospheric activity index: measure of magnetic activity of a star's chromosphere
- circumstellar disk: disk or ring shaped accumulation of matter around a star
- cold mass accretion (CMA): stellar accretion through an accretion disk
- color-color diagram (CCD): means of comparing characteristics of stars
- color-magnitude diagram (CMD,CM): graph plotting stars' color to luminosity
- color-period diagram: means of comparing periods of stars at various wavelengths
- convection zone: region of a star transmitting energy through convection
- core collapse supernova (CCSN): supernova resulting from the collapse of the core of a star
- corona: plasma surrounding a star
- coronal hole: cool, low-density portions of the Sun's corona
- coronal mass ejection (CME): mass of plasma ejected from the Sun
- COROT: observatory-satellite to look for transiting exoplanets and stellar oscillations
- CTIO Upper-Scorpius OB Association Survey (UScoCTIO): survey of low-mass stars and brown dwarfs
- debris disk: circumstellar disk of dust and debris around a star
- dredge-up: stellar convection bringing up fused material
- Dunlop Double Star Catalogue (DUN): 1829 catalog of double stars viewed from Australia
- dwarf nova (DN): flash of a cataclysmic variable star
- Eddington approximation: approximation of a star's internal EMR's divergence from isotropic
- Eddington luminosity: maximum luminosity at which radiation force overcomes gravity
- ejection: forcing or throwing something out
- evolutionary track: H-R diagram track of the life of a star
- field: adjective meaning "in this field of view but unrelated"
- Flamsteed designation: star designation system dating from 1700s
- Frank Ross's Catalog (Ross): high-proper-motion and variable stars catalogued by Frank Ross
- G-dwarf problem: lack of metal-poor G dwarfs in the Milky Way
- Gaia: 2010s astrometry survey satellite
- galactic disk: the "disk" portion of a disk galaxy
- galaxy main sequence: relation between galaxies' star formation and stellar mass
- General Catalog of Trigonometric Parallaxes (GCTP): 1950s star catalog with later updates
- General Catalogue of Stellar Radial Velocities (GCRV): 1950s century catalog of 1500 stars with radial velocities
- General Catalogue of Trigonometric Parallaxes (GCTP): 1950s catalog of stars with parallax measures
- General Catalogue of Variable Stars (GCVS): 20th/21st century catalog of 58000 variable stars
- Gliese Catalogue of Nearby Stars (Gl,Gliese): 1950s catalog of stars within 20 parsecs
- Gliese-Jahreiss Catalog (GJ): 1991 catalog of stars within 25 parsecs
- globular cluster (GC): spherical group of stars orbiting a galaxy
- Gould's Belt: ring of stars around the sky
- Guide Star Catalog (GSC,HSTGC): catalog of stars to help aim HST
- gyrochronology: means of estimating stellar age from rotation
- H-R diagram (HRD): diagram relating effective temperature to luminosity
- Hamburg/ESO Survey (HE): 1990s southern hemisphere survey aimed at finding quasars
- Hayashi limit: limit on the temperature of a star dependent upon its mass and luminosity
- Hayashi track: H-R diagram track of evolution of some pre-main-sequence stars
- Heggie-Hills law: hard binary stars generally get harder when encountering a third star
- helium flash: helium ignition in a star
- helium runaway: helium fusion positive feedback through its generated heat
- Henry Draper Catalog (HD): early 20th century spectroscopic catalog of stars
- Henyey track: H-R diagram track of stellar evolution after the Hayashi track
- Herschel Double Star Catalog (H): series of early double star catalogs
- Herz catalog (Herz): list of 3000 stars in a strip of the southern sky
- Hess diagram: diagram relating effective temperature to luminosity
- hypercompact stellar system (HCSS): SMBH with no galaxy but has a tight stellar cluster
- initial mass function (IMF): function describing initial mass of stars
- instability strip: region of H-R diagram where stars are unstable
- interstellar magnetic field (ISMF): galactic magnetic field between that of stars
- isothermal core: core region of a body of all the same temperature
- kappa mechanism (κ-mechanism): stellar instability caused by opacity increasing with temperature
- kilonova (KN): explosive event larger than a nova and smaller than a supernova
- Lépine Shara Proper Motion catalog (LSPM): 2000s catalog of stars with proper motion
- Lacaille Star Catalog (Lac): 1700s catalog of about 10,000 southern hemisphere stars
- LaSilla-QUEST Variability Survey (LSQ): survey for transients
- Lick indices: defined set of spectral line indexes for stars
- Lowell Proper Motion Survey (G): 1950s-1970s catalogs of stars with proper motion
- luminosity class: classification of size/luminosity of stars
- luminosity function (LF): function giving number of stars or galaxies at different luminosities
- luminous red nova (LRN): red-colored event theorized to be a merger of two stars
- Luyten Double Star Survey (LDS): 1940s-1970s catalog of double stars
- Luyten Half-second Catalog (LHS): 1979 catalog of 4000 stars with high proper motion
- Luyten Palomar Survey (LP): 1960s catalog of stars with high proper motion
- Luyten Two-Tenths Arcsecond Catalog (LTT): 1960 catalog of 9000+ stars with proper motion
- Magellanic Catalogue of Stars (MACS): 1980s/1990s survey of stars in Magellanic Clouds
- mass fraction: measure of a constituent of a star, cloud, etc.
- mass loss: a star's reduction in mass
- mass-luminosity relation: model relating stellar mass and luminosity
- mass-radius relation: model relating stellar mass and radius
- mass-to-light ratio (M/L,ϒ): measure of a population of stars or region
- Max Wolf's catalog of stars with proper motion: early 20th century catalog of 1500 stars
- mean molecular weight (μ): measurement of a gas usual for approximating in gas models
- microquasar: stellar-sized black hole with quasar-like activity
- moving group: observed group of stars with similar motion
- moving-cluster method: method of measuring distance to a nearby star cluster
- multiplicity fraction: fraction of star systems that are multiple-star systems
- MUSCLES: HST UV survey of some M Dwarfs that host exoplanets
- near-Earth supernova: supernova near enough to Earth to affect it
- New Catalogue of Suspected Variable Stars (NSV): catalog from latter half of 20th century catalog
- NOMAD: astrometric star catalog
- north polar sequence (NPS): set of stars previously used to define magnitudes
- nova (N): white dwarf explosion
- OB association: stellar association with O or B class stars
- Oort constants: two constants characterizing local Milky-Way motion
- open cluster (OC): group of stars within a galaxy apparently formed by a single cloud
- partial ionization zone: portion of some stars where gas is partially ionized
- PHOENIX stellar model: computer model of a stellar photosphere
- photosphere: layer of start from which light propagates
- Pico dos Dias Survey (PDS): survey aimed to find T-Tauri stars
- plane-parallel atmosphere: simplified atmosphere model ignoring its curvature around the body
- planetary nebula (PN): gas shell ejected by a red giant
- planetary system: all the planets orbiting a star
- PPM Star Catalogue: 1991 astrometric catalog with proper motions
- protoplanetary nebula (PPN): short AGB phase before planetary nebula
- protostar: contracted mass of gas that will become a star
- pseudobulge: like a galaxy bulge only flatter
- quadratic field strength: a measure of a star's varying magnetic field
- quasar (QSO): distant, bright object that appears something like a star
- Radcliffe Observatory Magellanic Clouds Catalogue (RMC): catalog of stars in
- radiation zone: region of a star transmitting energy through radiative diffusion
- RECONS: consortium for research on stars near the Sun
- reddening: red appearance of astronomical objects because blue light is attenuated by dust
- Rosseland mean opacity: a useful weighted average of opacities at all the wavelengths
- SAO Star Catalog: 1960s catalog
- Schönberg-Chandrasekhar limit: maximum stellar isothermal helium core mass
- Schuster-Schwarzschild model: simplified model of a star's production of absorption lines
- seismic waves: waves broadcast through Earth from earthquakes
- SIMP: 2000s infrared proper-motion survey
- snow line: distance from protostar cool enough for water to condense
- solar neighborhood: Milky Way in the vicinity of the Sun
- spectral class: overall classification of stars based upon spectral features
- spectral type: classification of stars based upon spectral features
- Spectroscopic Properties of Cool Stars (SPOCS): analysis of spectroscopic data of 7000+ M and L stars
- SSP: set of stars born at the same time with the same metallicity
- star cloud: lighter region of the night sky consisting of a high density of stars
- star count: surveys of stars counting them according to some criteria
- star formation (SF): theorized collapse of gas and dust into stars
- star system: a gravitationally bound set of a few stars
- STARBURST99: software to simulate star-forming galaxies
- stellar age determination: methods of estimating a star's age
- stellar association: like a large open cluster but even less tightly bound
- stellar astronomy: astronomy of the birth, structure, variety, evolution, and fate of stars
- stellar atmosphere: photosphere and above
- stellar birth rate function: function describing the birth rate of stars by mass
- stellar cluster (SC): group of stars apparently formed by a single cloud
- stellar core: the middle of a star
- stellar demographics: statistics regarding the number of stars
- stellar designation: identifiers for stars
- stellar distance determination: methods by which the distance to a star is determined
- stellar dynamics: stars' gravitational interaction
- stellar encounter: stars passing close to each other
- stellar evolution: the pattern of a star's changing structure over its life
- stellar flare: sudden brightening of a star
- stellar kinematics: science of the movement of stars
- stellar luminosity determination: methods by which the luminosity of a star is determined
- stellar mass determination: methods by which the mass of a star is determined
- stellar model atmosphere: simulation of the star's production of emitted EMR
- stellar parameter determination: methods by which the parameters of stars are determined
- stellar population synthesis (SPS): using spectral characteristics of galaxies to characterize their stellar populations
- stellar population synthesis code: software to perform stellar population synthesis
- stellar radius determination: methods by which the radius of a star is determined
- stellar rotation: rotation of a star around an axis through the middle
- stellar stream: long group of co-moving stars
- stellar structure: the presumed internal structure of stars
- stellar temperature determination: methods by which the temperature of a star is determined
- stellar wind: gas or plasma emanating from a star
- stellar-mass black hole: black hole that is a stellar remnant
- Struve Catalogs: two catalogs of double stars
- sunspot: temporary darker region of the Sun's surface
- SuperCOSMOS Sky Survey (SSS): survey of stars and galaxies from legacy plates
- superluminous supernova (SLSN): stellar explosion larger than a supernova
- supernova (SN): stellar explosion larger than a nova
- supernova impostor: extreme stellar explosion that does not destroy the star
- surface abundance: quantity such as mass per surface area
- surface gravity: force felt at the surface of a body
- surface temperature: temperature of the surface of a star or planet
- synthetic spectrum: simulated spectrum, e.g., of a type of star
- T association: stellar association with T-Tauri stars
- Taurus-Auriga Complex: nearby star-forming region
- thermal pulse: pulse in an AGB star due to helium fusion in a shell
- thermal runaway: situation where heat triggers more heat production
- tidal capture: bodies entering orbit through dissipation of energy by tides
- Tolman-Oppenheimer-Volkoff limit (TOV,LOV): maximum mass of a neutron star
- turn-off point (TO): point in H-R diagram of a cluster where stars turn red
- Two Micron All-sky Survey (2MASS): near-infrared survey of both hemispheres
- Two Micron Sky Survey (IRC,TMSS): 1969 infrared catalog produced by Caltech
- two-stream approximation: approximation of a star's internal EMR's divergence from isotropic
- Type Ia supernova: type of supernova for which distance can be determined
- USNO CCD Astrograph Catalog (UCAC): USNO star catalog including proper motions
- variable star designation: Bayer system variant for variable stars
- velocity-metallicity relation: higher stellar velocity correlates with lower metallicity
- VLT-FLAMES Tarantula Survey (VFTS): VLT spectroscopic survey of massive stars
- Vogt-Russell theorem: proposition that a star's structure depends on its mass and makeup
- Washington Double Star Catalog (WDS): modern database of double stars
- Whole Earth Telescope (WET): international initiative to gather variable star lightcurves
- Wilson-Bappu effect: a relation between a star's spectral line and luminosity
- WINGS: all-sky survey investigating known galaxy clusters
- zero-age main sequence (ZAMS): describes stars that just began hydrogen fusion
- StarScan machine:
- starshade: spacecraft to block light from a specific body
- Starshot: plan for mission to fly by Alpha Centauri
- STARSMOG: survey of dust in galaxies
- starspot:
- StarTrack: stellar population synthesis code
- state of excitation: energy level of something above the minimum
- state of ionization: difference in an ion's electron count versus proton count
- state of matter:
- STATIC:
- MAVEN: Mars orbiter to study its atmosphere
- static limit:
- black hole (BH): region of such high mass that light cannot escape
- static surface:
- black hole (BH): region of such high mass that light cannot escape
- statics:
- station keeping:
- stationkeeping: spacecraft operation to keep it in its orbit
- statistical dispersion:
- statistical equilibrium:
- statistical isotropy:
- statistical mechanics: mechanical behavior based upon probability
- statistical physics:
- statistical weight:
- statistics:
- stau:
- supersymmetry (SUSY): extension to standard model of particle physics
- steady-state universe:
- Big Bang: theoretical event when the universe expanded from a point
- steam atmosphere:
- steam phase:
- steam planet:
- Stefan's constant:
- Stefan-Boltzmann constant (σ): relates radiation power to temperature and surface area
- Stefan-Boltzmann equation:
- Stefan-Boltzmann law:
- Stein:
- stellar age:
- stellar age determination: methods of estimating a star's age
- stellar association: like a large open cluster but even less tightly bound
- stellar astronomy: astronomy of the birth, structure, variety, evolution, and fate of stars
- stellar atmosphere: photosphere and above
- stellar birth rate function: function describing the birth rate of stars by mass
- stellar black hole:
- stellar cluster (SC): group of stars apparently formed by a single cloud
- stellar core: the middle of a star
- stellar demographics: statistics regarding the number of stars
- stellar designation: identifiers for stars
- stellar distance:
- stellar distance determination: methods by which the distance to a star is determined
- stellar dynamics: stars' gravitational interaction
- stellar encounter: stars passing close to each other
- stellar envelope:
- stellar evolution: the pattern of a star's changing structure over its life
- stellar evolution model:
- stellar feedback:
- stellar flare: sudden brightening of a star
- stellar halo:
- galactic halo: spherical region around a galaxy with gas, dark matter, etc.
- stellar kinematics: science of the movement of stars
- stellar luminosity:
- stellar luminosity determination: methods by which the luminosity of a star is determined
- stellar magnetic field:
- stellar mass:
- stellar mass black hole:
- stellar mass determination: methods by which the mass of a star is determined
- stellar mass loss:
- stellar metallicity:
- stellar model:
- stellar model atmosphere: simulation of the star's production of emitted EMR
- stellar nucleosynthesis:
- stellar nucleus: group of many stars at the center of a galaxy
- stellar nursery:
- stellar occurrence rate:
- stellar parallax:
- parallax: angle due to different lines of sight
- stellar parameter determination: methods by which the parameters of stars are determined
- stellar population: grouping of stars according to metallicity
- stellar population synthesis (SPS): using spectral characteristics of galaxies to characterize their stellar populations
- stellar population synthesis code: software to perform stellar population synthesis
- stellar population synthesis model:
- stellar pulsation:
- stellar radio source:
- stellar radius:
- stellar radius determination: methods by which the radius of a star is determined
- stellar remnant: leftovers from a mainstream star
- stellar remnant black hole:
- stellar rotation: rotation of a star around an axis through the middle
- stellar seismology:
- stellar spot:
- sunspot: temporary darker region of the Sun's surface
- stellar stream: long group of co-moving stars
- stellar structure: the presumed internal structure of stars
- stellar structure model:
- stellar system:
- solar system: the Sun and what's gravitationally bound to it
- star system: a gravitationally bound set of a few stars
- stellar temperature:
- stellar temperature determination: methods by which the temperature of a star is determined
- stellar wind: gas or plasma emanating from a star
- stellar-mass black hole: black hole that is a stellar remnant
- stellar-mass star-formation rate ratio:
- stellar-structure equations:
- stellar-wind bubble:
- stencil: pattern of input to numerical solutions at a point
- Steph:
- steradian:
- STEREO: two-satellite system to observe the Sun
- sterile neutrino:
- neutrino (ν): light, electrically neutral elementary particle
- Sternberg Astronomical Institute:
- Sterncatalog für die Zone von 6° bis 10° südlicher Declination für das Aequinoctium 1890:
- Herz catalog (Herz): list of 3000 stars in a strip of the southern sky
- Steward Observatory 0.9-meter Spacewatch telescope:
- STF:
- STFC:
- StHA:
- stiff EoS:
- stimulated emission:
- emission: addition of photons to a beam of EMR
- maser: electromagnetic radiation amplified by stimulated emission
- STIS:
- STIX:
- STJ:
- Stk:
- Stokes number (Stk,St): measure of a particle's tendency to flow the flow of a fluid
- StKM:
- stochastic background:
- Stokes map:
- Stokes number (Stk,St): measure of a particle's tendency to flow the flow of a fluid
- Stokes parameters: means of describing a polarization state
- stop:
- Lyot stop: optical element to block unwanted light within instruments
- Str:
- Strömgren photometric system: four-color photometric system devised in 1950s
- Strömgren sphere: sphere of ionized hydrogen around an OB star
- strange matter:
- quark matter (QM): matter not made of protons and neutrons but of quarks
- strange quark:
- exotic star: term for theoretical stars not made of atoms/ions
- particle: very small thing
- quark matter (QM): matter not made of protons and neutrons but of quarks
- standard model: model of elementary particles including quarks
- strange quark matter:
- exotic star: term for theoretical stars not made of atoms/ions
- neutron star (NS): stellar remnant consisting entirely of solar masses of neutrons
- quark matter (QM): matter not made of protons and neutrons but of quarks
- strange star:
- exotic star: term for theoretical stars not made of atoms/ions
- quark matter (QM): matter not made of protons and neutrons but of quarks
- Strasbourg Astrophysical Data Center:
- Strasbourg-ESO Catalog of Galactic Planetary Nebulae (PNG): 1992 catalog of 1820 objects
- stratigraphy: study of rock layering
- stratopause:
- stratosphere:
- Stratospheric Observatory for Infrared Astronomy:
- SOFIA: aircraft-based infrared observatory
- stray light: unintended light reaching a telescope's sensors
- stray light mitigation:
- stray light: unintended light reaching a telescope's sensors
- Strehl ratio: measure of optical aberration
- wavefront error (WFE): measure of a telescope's distortion of incoming waves
- strewn field: region with fragments of a meteor impact
- strewn-field:
- strewnfield:
- striae: parallel ridges
- string:
- string theory: type of physics theory bringing together current models
- string theory: type of physics theory bringing together current models
- strong cosmic censorship:
- strong CP problem:
- axion (A0): proposed light, electrically neutral elementary particle
- strong encounter:
- strong force: force that holds quarks and nuclei together
- electroweak: single conception including both electromagnetic and weak forces
- particle: very small thing
- quark: type of elementary particle incorporated in protons and neutrons
- Theory of Everything (TOE): single law explaining the four forces of nature
- topological defect: defect in space that could arise in the early universe
- strong gravitational encounter:
- strong gravitational interaction:
- strong gravitational lensing:
- weak lensing (WL): slight lensing detected in random patterns of distant objects
- strong interaction:
- N-body problem: calculating the paths of gravitationally-interacting celestial objects
- strong force: force that holds quarks and nuclei together
- strong lensing:
- weak lensing (WL): slight lensing detected in random patterns of distant objects
- Strong Radio Source Surveys:
- Strong Source Surveys: series of 1970s/1980s 5 GHz surveys
- strong stellar encounter:
- strong-field gravity: gravity much stronger than in the solar system such as near a black hole
- strong-field gravity physics:
- strontium:
- Am star: A-type star with metallic lines
- Ap star: peculiar type of A star
- structure:
- Struve:
- Struve 1341 B b:
- Struve Catalogs: two catalogs of double stars
- STScI:
- STT:
- STTA:
- Styx:
- Pluto: dwarf planet formerly listed as one of the nine planets
- sub Neptune:
- super-Earth: exoplanet more massive than Earth but substantially less than Neptune
- sub-brown dwarf:
- sub-Neptune:
- mini-Neptune: planet with characteristics a bit like Earth but more like Neptune
- Subaru:
- Subaru Deep Field (SDF): survey of a small region of the sky using the Subaru telescope
- Subaru Telescope: 8.2 meter telescope in Hawaii
- Subaru XMM Deep Survey:
- Subaru XMM-Newton Deep Field:
- Subaru XMM-Newton Deep Survey (SXDS): survey using the Subaru telescope and XMM-Newton
- subduction zone:
- Europa: well-known Jupiter moon
- subdwarf (sd,VI): star less bright than the main sequence given its spectral class
- subgiant: slightly larger than normal star
- subgiant branch:
- subgiant: slightly larger than normal star
- subgrid physics:
- subgrid-scale physics: shortcuts handling physics on a smaller scale than a simulation's grid
- subgroup:
- galaxy group: group of fifty or fewer gravitationally bound Milky-Way-sized galaxies
- galaxy subgroup: group of fifty or fewer gravitationally bound Milky-Way-sized galaxies
- Milky Way subgroup: the Milky Way and its satellites
- subhalo:
- sublimation: single material phase transition from solid to gas
- submillimeter:
- Submillimeter Array (SMA): radio interferometer in Hawaii
- submillimeter astronomy: astronomy observation and analysis of borderline infrared EMR
- far infrared (FIR,far-IR): infrared radiation with wavelengths in the 30-450 μm range
- submillimeter galaxy (SMG): galaxy that produces significant submillimeter radiation
- submillimeter galaxy designator: designation system of submillimeter galaxies
- Submillimeter Telescope (SMT,HHSMT): 10 meter far-infrared telescope
- submillimeter-selected galaxy:
- submillimetre astronomy:
- Submillimetre Common-user Bolometer Array:
- SCUBA: submillimeter instrument on James Clark Maxwell Telescope
- submoon:
- Suborbital Polarimeter for Inflation Dust and the Epoch of Reionization:
- SPIDER: 2015 airborne observatory to observe CMB polarization
- subradio: electromagnetic radiation, frequency below 3 kHz
- subsatellite: object orbiting a moon
- substar:
- Substellar and Planetary Atmospheric Radiation and Circulation:
- MITgcm: well-known general circulation model
- substellar object: star-like object with less mass than a star
- subsumption band:
- Europa: well-known Jupiter moon
- SUDA:
- sudden ionospheric disturbance:
- sugars:
- Lego principle: principle that life is associated with a skew in molecule abundances
- SUGRA:
- supergravity (SUGRA): combination of general relativity and supersymmetry
- supersymmetry (SUSY): extension to standard model of particle physics
- sulci:
- Enceladus: Saturn moon considered possible carrier of life
- sulfide:
- geochemistry: the chemistry of the Earth, planets, and moons
- sulfur (S): metal, S, atomic number 16
- SUMER:
- summer solstice:
- solstice: moment when Sun reaches its northern- or southern-most position
- Sun: star at center of solar system
- Sun surface features: features on the Sun's surface
- sunspot: temporary darker region of the Sun's surface
- sunspots:
- Sunyaev-Zel'dovich Array (SZA): array of eight 3.5 meter microwave telescopes
- Sunyaev-Zel'dovich effect (SZ effect,SZ,SZE): type of distortion of the CMB
- super giants:
- super Jupiters:
- super low frequency (SLF): electromagnetic radiation, frequency 30 Hz to 300 Hz
- super Neptune:
- super rotation:
- super-Earth: exoplanet more massive than Earth but substantially less than Neptune
- 55 Cancri e (55 Cnc e): superearth orbiting a Sun-like star
- GJ 1214 b: super-Earth extrasolar planet discovered in 2009
- Kepler-452b: Earth-like exoplanet discovered in 2015
- LHS 3844 b: red dwarf with rocky planet in its habitable zone
- mini-Neptune: planet with characteristics a bit like Earth but more like Neptune
- OGLE-2005-BLG-3290Lb: exoplanet orbiting a binary star
- Proxima b: exoplanet orbiting Proxima Centauri
- super-Eddington accretion:
- accretion: enlargement of an astronomical body by gravitationally attracting additional mass
- Eddington luminosity: maximum luminosity at which radiation force overcomes gravity
- super-Eddington luminosity:
- Super-LOTIS:
- super-puff:
- super-Earth: exoplanet more massive than Earth but substantially less than Neptune
- SUPERBLINK:
- superbubble:
- shell: hollow shaped region of some kind of ISM
- supershell: very large ISM shell-shaped region
- SuperCam:
- Mars 2020: Mars rover in development for 2020 launch
- supercluster: cluster of galaxy clusters
- supercluster complex:
- superclusters:
- superconducting fluid:
- neutron star (NS): stellar remnant consisting entirely of solar masses of neutrons
- superconducting tunnel junction (STJ): type of Josephson junction usable in EMR sensors
- superconductor:
- flux freezing: magnetic field lines becoming attached to plasma they pass through
- superconductor-isolation-superconductor:
- supercooled state:
- supercooling: cooling water below freezing point without it freezing
- supercooling: cooling water below freezing point without it freezing
- SuperCOSMOS:
- SuperCOSMOS Sky Survey (SSS): survey of stars and galaxies from legacy plates
- SuperCOSMOS Sky Surveys:
- supercritical fluid (SCF): state of matter at sufficient pressure and temperature
- superearth:
- super-Earth: exoplanet more massive than Earth but substantially less than Neptune
- superflare:
- superfluid: fluid with no viscosity
- superfluidity:
- supergalactic coordinate system: celestial coordinate system system based upon the supergalactic plane
- supergalactic latitude:
- supergalactic longitude:
- supergalactic plane:
- supergiant: very large giant star
- supergiant elliptical galaxy:
- supergiant star:
- supergranulation:
- Sun: star at center of solar system
- supergranule:
- supergravity (SUGRA): combination of general relativity and supersymmetry
- supersymmetry (SUSY): extension to standard model of particle physics
- superionic ice: odd state of water at high temperature and pressure
- superionic water:
- superionic water ice:
- superior planet:
- superluminal motion: faster-than-light movement
- superluminous SN:
- superluminous supernova (SLSN): stellar explosion larger than a supernova
- supermassive binary black hole:
- supermassive black hole (SMBH): black hole with a mass of millions to billions of solar masses
- supermassive black hole binary:
- binary SMBH (BSMBH,SMBBH,SMBHB): co-orbiting supermassive black holes
- supermassive black holes:
- supermassive neutron star:
- supermassive star (SMS): star more massive than stars normally form
- supernova (SN): stellar explosion larger than a nova
- Cassiopeia A: supernova remnant visible for 300 years
- 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
- Supernova Acceleration Probe:
- Supernova Cosmology Project (SCP): used supernova data to determine a history of the universe's expansion
- supernova designator: typical designation of supernovae
- Supernova Early Warning System:
- Supernova Factory Galaxy:
- NGC 2770: spiral galaxy 88 million light-years away
- supernova Hubble diagram:
- supernova impostor: extreme stellar explosion that does not destroy the star
- Supernova Legacy Survey (SNLS): detect and monitor supernovae to measure the effects of dark energy
- supernova nucleosynthesis:
- supernova remnant (SNR): nebula of debris resulting from a supernova
- supernova (SN): stellar explosion larger than a nova
- supernova survey: survey to identify and/or study supernovae
- supernovae:
- superparticle:
- supersymmetry (SUSY): extension to standard model of particle physics
- superposition:
- linear theory: theory of operators satisfying the property of superposition
- superradiance: Exotic quantum-mechanics light-amplification phenomenon
- superrotating jet:
- superrotating wind: wind traveling in the same direction as the planet is rotating
- supershell: very large ISM shell-shaped region
- shell: hollow shaped region of some kind of ISM
- supersonic parachute:
- drogue chute: parachute to slow something moving at high speed
- supersymmetry (SUSY): extension to standard model of particle physics
- neutralino: proposed type of particle that might include wimps
- supergravity (SUGRA): combination of general relativity and supersymmetry
- supervoid:
- void: empty spaces between large scale structures
- SuperWASP (SWASP): broad Earth-based search for transiting planets
- SuperWASP North:
- WASP-33b: hot Jupiter discovered in 2010
- SuperWASP-North:
- SuperWASP (SWASP): broad Earth-based search for transiting planets
- superwind:
- supramassive neutron star:
- suprathermal: having more energy than would be created by thermal excitation
- suprathermal electron:
- suprathermal: having more energy than would be created by thermal excitation
- suprathermal ion:
- suprathermal: having more energy than would be created by thermal excitation
- suprathermal particle:
- suprathermal: having more energy than would be created by thermal excitation
- suprathermal tail:
- suprathermal: having more energy than would be created by thermal excitation
- Suprime-Cam:
- surface:
- surface abundance: quantity such as mass per surface area
- surface brightness (SB): brightness per unit area of a surface
- surface brightness fluctuation (SBF): apparent indication of an elliptical galaxy's distance
- surface brightness fluctuations method:
- surface density (Σ): quantity such as mass per surface area
- surface error:
- wavefront error (WFE): measure of a telescope's distortion of incoming waves
- surface gravity: force felt at the surface of a body
- surface of last scattering: sphere around us from which CMB photons are just reaching us
- surface reaction: such as reactions between gas and adjacent liquid
- surface temperature: temperature of the surface of a star or planet
- survey:
- 1 Jansky Empty Field Survey (1 Jy): survey to find optical identifications for weak radio sources
- 2dF Galaxy Redshift Survey (2dFGRS): imaging survey of 300,000 objects
- 2dF-SDSS LRG and QSO survey (2SLAQ): spectroscopic survey of distant galaxies
- 3D-HST: near-infrared survey of 100,000 galaxies by HST
- 87GB Catalog of Radio Sources (87GB): 1980s Green Bank radio survey
- AEGIS: survey study of distant galaxies
- AFGL Four Color Infrared Sky Survey (AFGL): 1970s infrared survey
- AIM-CO: survey of CO from star forming epoch
- ALFALFA: HI survey of many galaxies
- All Sky Automated Survey (ASAS): Polish survey of 20,000 objects brighter than 14 magnitude
- All Sky Automated Survey for SuperNovae (ASAS-SN,ASASSN): survey of both hemispheres for supernovae
- ALMA-PILS Survey: millimeter survey of a protostar
- APASS: down to 16 magnitude
- APM Galaxy Survey (APMUKS): 1990s survey of galaxies in southern sky
- Arecibo Occultation Survey (AO): 1960s radio survey using occultations by the Moon
- ASPECS: millimeter survey of HUDF
- Astrographic Catalog (AC): historical star catalog of the whole sky to magnitude 11
- astronomical survey: project to collect uniform astronomical data across the sky
- Atacama B-Mode Search (ABS): 2012-2014 survey of the CMB
- Atlas 3D: survey of local galaxies
- Australia Telescope Large Area Survey (ATLAS): radio survey of two survey fields
- Badgerys Creek Interferometer 101MHz Survey (Mills): early 1950s survey of southern-hemisphere radio sources
- Baryon Oscillation Spectroscopic Survey (BOSS): survey of spatial distribution of luminous red galaxies and quasars
- BATC: photometric survey of Milky Way stars
- BICEP2: survey to measure the polarization of the CMB
- BigBOSS: BOSS survey follow-on
- Bologna Survey of Radio Sources: 1970s-1980s radio survey
- Breakthrough Listen (BL): SETI survey using GBT and Parkes Observatory
- Bruce Proper Motion Survey (BPM): 1941 southern-hemisphere survey catalog of Luyten's
- C-BASS: 6 cm survey of the entire sky
- Calán/Tololo Survey: late 1980s to early 1990s search to redshift 0.1
- CALIFA: spectroscopic map of 600 galaxies
- California-Kepler Survey (CKS): followup to Kepler to determine stellar radii
- Campo Imperatore Near-Earth Object Survey (CINEOS): survey of near-Earth objects
- Canada-France High-z Quasar Survey (CFHQS): 2000s distant quasar survey
- Canada-France Redshift Survey (CFRS): 1990s survey of galaxies to z = 1 to find associations of redshift to characteristics
- Canadian Cluster Comparison Project (CCCP): multi-wavelength survey of fifty X-ray-selected galaxy clusters
- CARMA EDGE: CO survey of galaxies
- Carnegie Supernova Project (CSP): survey of supernovae lightcurves
- Case-Hamburg Survey (LS): 1950s-1970s survey(s) of OB stars
- Catalina Sky Survey (CSS): survey of near-Earth objects
- CfA Redshift Survey: 1970s-1990s surveys of galaxy redshifts
- CFBDS: survey in search of brown dwarfs
- CFHTLS: surveys of transients and stars
- Chandra Deep Field North (CDFN,CDF-N): X-ray deep survey encompassing HDF region
- Chandra Deep Field South (CDFS,CDF-S): X-ray deep survey encompassing HDF-South region
- COLD GASS: survey of CO in nearby large galaxies
- COMPLETE Survey: survey of star forming regions
- COPSS: survey of CO from star forming epoch
- Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS): early universe survey by HST
- Cosmic Evolution Survey (COSMOS): investigation of dark matter and the universe's large scale structure
- Cosmic Lens All-sky Survey (CLASS): radio survey aimed at gravitational lenses
- CRATES: catalog of 8.4 GHz data on radio sources
- CTIO Upper-Scorpius OB Association Survey (UScoCTIO): survey of low-mass stars and brown dwarfs
- Dark Energy Survey (DES): survey aimed at mapping the universe's expansion
- DASCH: project to digitize Harvard astronomy plates
- DECaLS: survey imaging part of SDSS footprint with DECam
- DEEP2: redshift survey of 60,000 galaxies
- DeGaS-MC: GBT survey of potential star formation regions in the Magellanic Clouds
- DENIS: 1990s southern sky survey of two near-infrared bands
- DEVILS: visible-light spectrographic survey of 56k distant galaxies
- Digitized Sky Survey (DSS): digitization of Palomar and UK Schmidt plates
- Dominion Observatory 10.03 MHz Source Catalog (DB): 1960s survey of northern-hemisphere radio sources
- Dominion Observatory 1420 MHz Source Catalog (DA): 1960s survey of northern-hemisphere radio sources
- Dwingeloo Obscured Galaxy Survey (DOGS): radio survey of ZOA for 21-cm lines indicating galaxies
- EMPIRE Survey: survey of gas in M51a to follow up PAWS
- EROS: search for MACHOs
- eROSITA: Russian/German space X-ray telescope launched in 2019
- ESO Nearby Abell Cluster Survey (ENACS): 1990s spectroscopy and photometry survey of galaxy clusters
- ESO/Uppsala Survey of the ESO (B) Atlas: 1970s southern all-sky survey
- ESSENCE: survey using supernova data to study dark energy
- Extended Chandra Deep Field-South Survey (ECDFS): 1100 square arcminute X-ray survey
- Faint Infrared Grism Survey (FIGS): survey to identify redshift of distant galaxies
- FIRST: 1990s radio survey
- FourStar Galaxy Evolution Survey (ZFOURGE,Z-FOURGE): infrared deep-survey to detect galaxies
- Fourth Cambridge Catalog of Radio Sources (4C): 1960s catalog of northern hemisphere 178 MHz sources
- Gaia: 2010s astrometry survey satellite
- Galactic All-sky Survey (GASS): HI survey of the Milky Way
- Galactic Emission Mapping (GEM): radio sky survey
- GALAH: survey of Milky Way with an emphasis on old structures
- Galaxy Zoo 2 (GZ2): crowd-sourced classification of hundreds of thousands of galaxies
- GALEX Arecibo SDSS Survey (GASS): HI survey of many galaxies
- GAMA: galaxy spectroscopy survey to roughly 1 Mpc
- GMAN: collaboration to alert on microlensing transients
- GOODS: survey combining data from different sources on very distant objects
- GOODS NICMOS Survey (GNS): survey with HST NICMOS instrument of galaxies in GOODS fields
- Gould's Belt Distances Survey (GOBELINS): survey of parallax distances to Gould's Belt YSOs
- Green Bank 6-cm Radio Source Catalog (GB6): catalog of from 1980s northern-hemisphere radio survey
- Ground-Base Electro-Optical Deep Space Surveillance (GEODSS): initiative to track artificial spacecraft including space junk
- Hamburg Schmidt Survey (HS): photographic plates from the Hamburg Schmidt Camera
- Hamburg/ESO Survey (HE): 1990s southern hemisphere survey aimed at finding quasars
- HATNet: distributed array of telescopes to search for transients
- Hawaii K-band Galaxy Survey: near-infrared survey of a selection of fields
- HBK: study of M31 globular clusters
- Herschel Orion Protostar Survey (HOPS): survey of SEDs of YSOs in Orion
- Herschel Redshift Survey (HeRS): 70 square-degree survey of galaxies redshifted 1.8 to 3.5
- Hewitt & Burbidge Catalog (HB87): optical catalog of quasi-stellar objects
- HI 4-Pi Survey (HI4PI): HI map based upon EBHIS and GASS
- HIPASS: HI survey carried out 1997 to 2002
- Hubble Deep Field (HDF,HDF-N): highly-detailed image of a small region of the sky taken with HST
- Hubble Deep Field South (HDF-S): small region of the southern sky explored with HST
- Hubble Ultra-Deep Field (HUDF): extremely detailed HST image of a small region of space
- Hydrogen Accretion in Local Galaxies Survey (HALOGAS): radio survey looking for HI in galaxy halos
- IPHAS: H-alpha survey
- KELT: pair of telescopes searching for transients
- Kiso Survey of Ultraviolet Excess Galaxies (KUG): 1980 Japanese survey
- KMOS3D: survey of galaxies before to after peak star formation
- LABOCA Extended Chandra Deep Field-South Submillimetre Survey (LESS): submillimeter survey of a well-studied piece of sky
- Large Bright QSO Survey (LBQS): 1980s quasar survey
- Las Campanas Redshift Survey (LCRS): 1990s survey of galaxies out to z = 0.2
- LaSilla-QUEST Variability Survey (LSQ): survey for transients
- Lick Observatory Calcium Line Survey (LkCl): 1980s survey of T-Tauri stars in the Taurus-Auriga Complex
- Lick Observatory Supernova Search (LOSS): search for supernovae for cosmological study
- LINEAR: survey of near-Earth objects
- LONEOS: survey of near-Earth objects
- Lupus Transit Survey: survey for hot Jupiters in a region of constellation Lupus
- MACHO Project: survey searching out microlensing that could indicate a MACHO
- Magellanic Catalogue of Stars (MACS): 1980s/1990s survey of stars in Magellanic Clouds
- Magellanic Clouds Photometric Survey (MCPS): UBVI survey of the Magellanic Clouds
- Markarian galaxy (Mkn): list of galaxies with excess ultraviolet light
- MASCARA: distributed array of telescopes to search for exoplanets
- Massive Cluster Survey (MACS): survey of distant clusters evident in ROSAT X-ray data
- MEarth Project (MEarth): automated observatories monitoring nearby red dwarfs for transits
- Medium Deep Survey (MDS): survey to find galaxies in HST WFPC2 images
- Microlensing Planet Search (MPS): program to follow up on microlensing detections
- MIGHTEE: radio survey of four established deep fields
- Millennium Galaxy Catalogue (MGC): 2000s catalog of 10,000 galaxies
- Millimeter-wave Intensity Mapping Experiment (mmIME): project to map CO an [CII]
- MOA: search for microlensing events
- MOJAVE: program to monitor AGN jet radio brightness and polarization
- Molecular Deep Field: survey of molecular lines in Hubble Deep Field
- Multi-Epoch Nearby Cluster Survey (MENeaCS): Type Ia supernova survey in clusters at z = 0.1
- Multiwavelength Survey by Yale-Chile (MUSYC): optical/NIR survey of four deep fields
- Munich Near-Infrared Cluster Survey (MUNICS): 1990s-2000s galaxy cluster survey
- MUSCLES: HST UV survey of some M Dwarfs that host exoplanets
- Nearby Supernova Factory (NSNF,SNfactory): survey that scanned transient data for supernovae
- NGTS: survey of transits from Chile
- NRAO Catalog (NRAO): 1960s followup to Cambridge radio surveys
- NRAO VLA Sky Survey (NVSS): 1990s microwave survey of 82% of the sky
- OGLE: survey searching for microlensing transients
- Ohio Radio Survey (OSS): 1960s radio survey by Ohio State University
- Outer Solar System Origins Survey (OSSOS): survey searching for trans-Neptune objects
- PALFA: Arecibo survey for pulsars
- PALMS: survey to find exoplanets for direct imaging
- Palomar Four-filter Survey (PC): Hale telescope survey aimed at discovering high-redshift quasars
- Palomar Observatory Sky Survey (POSS): 1950s photographic plates from Palomar 48 inch telescope
- Palomar Transient Factory (PTF): survey designed to find transients
- Palomar-Green Survey (PG): list of objects with excess ultraviolet light
- Palomar-Leiden Survey (PLS): 1960s survey to identify distant asteroids
- Pan-STARRS: set of survey telescopes
- PanCET: HST UV/optical/NIR survey of selected exoplanets
- PAndAS: survey of M31 and M33
- Parkes Catalog (PKS): catalog of from 1960s-1990 of radio sources in southern hemisphere
- Parkes HI Zone of Avoidance Survey (HIZOA): radio survey to identify galaxies hidden by the zone of avoidance
- Parkes Multibeam Pulsar Survey (PMPS): late 1990s radio survey in search of pulsars
- Parkes Pulsar Timing Array (PPTA): group of pulsars timed by Parkes Observatory
- Parkes-MIT-NRAO Surveys (PMN): 1990 southern-hemisphere radio surveys
- PAWS: survey of GMCs in M51a
- PEP: survey aimed at early star formation
- PESSTO: survey for transients carried out on the NTT
- PHIBSS: survey of CO in distant galaxies
- Pi of the Sky: survey aimed at finding gamma-ray-burst visual counterparts
- Pico dos Dias Survey (PDS): survey aimed to find T-Tauri stars
- Planet Crossing Asteroid Survey (PCAS): search for NEOs using small Palomar Schmidt Camera
- POINT-AGAPE: survey of M31 for microlensing
- POLARBEAR: instrument to map CMB polarization
- Pre-OmegaTranS (POTS): transit search using MPG/ESO Telescope
- PRIMUS: spectrographic survey of galaxies out to redshift 1
- Probing Lensing Anomalies Network (PLANET): survey that recorded microlensing event lightcurves
- Qatar Exoplanet Survey (QES): photometric survey in search of transients
- QUIJOTE: survey to measure the polarization of the CMB
- Radio Galaxy Zoo (RGZ): crowd-sourced classification of radio galaxies
- Rosat Bright Survey (RBS): list of bright X-ray sources from ROSAT observations
- Rosat Hard Survey (RHS): list of hard X-ray sources from ROSAT observations
- SAGE: survey of gas and dust in the Magellanic Clouds
- Sagittarius Window Eclipsing Extrasolar Planet Search (SWEEPS): transit search using HST time
- Second Byurakan Survey (SBS): 1970s-1990s survey of galaxies and quasars
- SHARDS: GTC survey in GOODS-N field for quenched galaxies at z 1-2.3
- SIMP: 2000s infrared proper-motion survey
- SINS: near-infrared study of distant luminous galaxies
- SKHB: survey of globular clusters in M31
- SkyMapper Southern Survey (SMSS): digital survey of the southern hemisphere sky
- Sloan Digital Sky Survey (SDSS): imaging survey of 500,000,000 objects in 35% of sky
- SPACEWATCH: survey to study minor planets
- SPECULOOS: search for Earth-like exoplanets orbiting nearby dim stars
- SPHEREx: all-sky spectral survey space-mission plan
- SPIRITS: Spitzer survey designed to find transients
- Spitzer Extended Deep Survey (SEDS): survey of galaxy mass and black holes through life of the universe
- Spitzer Extragalactic Representative Volume Survey (SERVS): infrared survey of some well-studied fields
- Spitzer HETDEX Exploratory Large Area Survey (SHELA): Spitzer-based survey of galaxies
- STARSMOG: survey of dust in galaxies
- Strong Source Surveys: series of 1970s/1980s 5 GHz surveys
- Subaru Deep Field (SDF): survey of a small region of the sky using the Subaru telescope
- Subaru XMM-Newton Deep Survey (SXDS): survey using the Subaru telescope and XMM-Newton
- SuperCOSMOS Sky Survey (SSS): survey of stars and galaxies from legacy plates
- Supernova Cosmology Project (SCP): used supernova data to determine a history of the universe's expansion
- Supernova Legacy Survey (SNLS): detect and monitor supernovae to measure the effects of dark energy
- SuperWASP (SWASP): broad Earth-based search for transiting planets
- Swope Supernova Survey (SSS): survey of low-redshift Type Ia SN light curves
- Texas Survey of Radio Sources at 365 MHz (TXS): 1970s/1970s radio survey made with the Texas Interferometer
- The H2O Southern Galactic Plane Survey (HOPS): survey of molecular clouds in the galactic plane
- The Survey for Ionization in Neutral Gas Galaxies (SINGG): survey of H-alpha in galaxies found through the HI line
- Tomographic Ionized-carbon Mapping Experiment (TIME): proposed instrument to map the [CII] line
- Tonantzintla Surveys (Ton): surveys providing early images of quasars and Seyfert galaxies
- Trans-Atlantic Exoplanet Survey (TrES): exoplanet-search survey using three telescopes
- Two Micron All-sky Survey (2MASS): near-infrared survey of both hemispheres
- Two Micron Sky Survey (IRC,TMSS): 1969 infrared catalog produced by Caltech
- UK Schmidt Survey: photographic survey of the southern hemisphere sky
- UKIDSS: five-part infrared survey using UKIRT
- Ultimate Spitzer Phase Curve Survey (USPCS): investigation of exoplanet atmospheres
- Ultraviolet Hubble Ultra-deep Field (UVUDF): ultraviolet data covering the Hubble Ultra Deep Field region of the sky
- UltraVISTA: near infrared survey using VISTA telescope
- Uppsala-ESO Survey of Asteroids and Comets (UESAC): 1990s comet and asteroid survey
- UTMOST: telescope aiming to detect radio transients
- VIMOS Public Extragalactic Redshift Survey (VIPERS): spectrographic redshift survey of 80,000 galaxies
- VIMOS-VLT Deep Survey (VVDS): spectroscopic survey of 100,000 high-redshift galaxies
- VLT-FLAMES Tarantula Survey (VFTS): VLT spectroscopic survey of massive stars
- WASP: multi-university initiative to locate transiting planets
- Westerhout Radio Survey (W): 1950s radio survey of the galactic plane
- WFCAM Transit Survey (WTS): 2000s survey for exoplanet transits using UKIRT
- Whole Earth Blazer Telescope (WEBT): international initiative to gather blazar lightcurves
- Whole Earth Telescope (WET): international initiative to gather variable star lightcurves
- WiggleZ: survey aimed at mapping dark energy
- WINGS: all-sky survey investigating known galaxy clusters
- XMM Cluster Survey (XCS): survey of existing XMM-Newton data to find galaxy clusters
- XO Project: initiative to search for transiting planets
- ZEPLIN: experiment to identify WIMPs with a tank of xenon
- Survey and Time-domain Astrophysical Research Explorer:
- STAR-X: concept for a future X-ray space telescope
- survey depth: indication of how far a survey reaches
- survey field: portion of the celestial sphere where a survey's observations aim
- Survey for High-z Absorption Red & Dead Sources:
- SHARDS: GTC survey in GOODS-N field for quenched galaxies at z 1-2.3
- survey region:
- survey field: portion of the celestial sphere where a survey's observations aim
- survey-based designator: astronomical object designators based on name of survey
- Surveying the Agents of Galaxy Evolution:
- SAGE: survey of gas and dust in the Magellanic Clouds
- surveys:
- astronomical survey: project to collect uniform astronomical data across the sky
- blind survey: survey conducted independently of prior information
- cadence: period between observations
- completeness: measure of how many of a survey's objects of a certain magnitude have been detected
- deep field (DF): survey field subject to lengthy observation to identify distant galaxies
- deep survey: survey using lengthy observation to identify distant galaxies
- Fsky (fsky): fraction of the sky, e.g., what a survey covers
- Hα survey: survey looking for the Hα line, typically to find star formation
- legacy survey: phrase sometimes used in survey names
- MAST: archive of data from surveys and missions
- QUEST: sixteen square-degree survey camera
- redshift space: concept of space using redshift as the radial dimension
- redshift survey: survey of the universe aiming at three dimensions
- scan speed: the speed at which the telescope changes angle on the sky while observing
- slew survey: survey conducted by imaging during a telescope's repointings
- star count: surveys of stars counting them according to some criteria
- supernova survey: survey to identify and/or study supernovae
- survey depth: indication of how far a survey reaches
- survey field: portion of the celestial sphere where a survey's observations aim
- survey-based designator: astronomical object designators based on name of survey
- SUSI:
- SUSIM:
- SUSY:
- supersymmetry (SUSY): extension to standard model of particle physics
- Sutherland Observatory:
- Sutherland Observing Station:
- Sutherland Station:
- Suzaku: space X-ray telescope
- SW effect:
- SWA:
- SWAN:
- SWAP:
- SWASP:
- SuperWASP (SWASP): broad Earth-based search for transiting planets
- SWAVES:
- STEREO: two-satellite system to observe the Sun
- SWCam:
- CCAT: 25-meter submillimeter telescope plan for Chile
- SWE:
- SWEA:
- MAVEN: Mars orbiter to study its atmosphere
- Swedish:
- SMART-1: Swedish lunary orbiter operational 2004-2008
- sweep signal:
- chirp: burst of signal rising or falling in frequency
- SWEEPS:
- SWeffect:
- SWEPAM:
- SWI:
- JUICE: mission to Jupiter in development
- SWIA:
- MAVEN: Mars orbiter to study its atmosphere
- SWICS:
- Swift: satellite for studying gamma-ray bursts
- Swift Gamma-Ray Burst Mission:
- Swift: satellite for studying gamma-ray bursts
- SWIMS:
- swing by:
- Mars: well-explored planet in the solar system
- SWIRC:
- MMT: 6.5 meter telescope at Mt. Hopkins, Arizona
- SWIRE:
- Swiss T70 Telescope:
- TRAPPIST: ground-based automatic transiting planet finding telescope
- SWOOPS:
- Ulysses: space mission to observe the Sun from off the ecliptic
- Swope Supernova Survey (SSS): survey of low-redshift Type Ia SN light curves
- Swope Telescope:
- Swordy plot:
- cosmic rays (CR): very-high-energy particles from beyond the solar system
- SWP:
- SWR:
- SWS:
- SX Arietis variable:
- SX Phoenicis variable:
- SXARI:
- SXC:
- SXDF:
- SXDS:
- SXG:
- Spektr-RG (SRG, SXG): Russian-German X-ray observatory launched in 2019
- SXI:
- ASTRO-H: Japanese space X-ray telescope
- SXPHE:
- SXS:
- ASTRO-H: Japanese space X-ray telescope
- SXT:
- ASTRO-H: Japanese space X-ray telescope
- Yohkoh: 1990s Japanese solar observatory spacecraft
- Sydney University Stellar Interferometer:
- symbiotic binary (SS): giant star transferring mass to a somewhat distant companion
- symbiotic star:
- symbiotic binary (SS): giant star transferring mass to a somewhat distant companion
- symbol:
- Z+: symbol for ion or ion charge
- symmetric mass ratio:
- chirp mass (Mc,ℳ): a reduced-mass-like quantity that relates to gravitational waves
- symmetry breaking: loss of symmetry, such as due to loss of stability in a regime change
- synchronous orbit: orbit with angular velocity matching the rotation of the orbited body
- synchronous rotation:
- synchrotron:
- synchrotron luminosity:
- synchrotron maser:
- maser: electromagnetic radiation amplified by stimulated emission
- synchrotron radiation: radiation emitted when high-speed charged particles are accelerated
- synchrotron self-absorption:
- synchrotron self-Compton (SSC): charged particle cloud scattering its own synchrotron-produced photons
- synchrotron self-scattering:
- synestia model:
- synodic period: period until a planet returns to the same position relative to the Sun
- orbital period: length of time for an orbiting object to complete one cycle
- synoptic: general, covering everything
- synthesis imaging:
- Synthesis Telescope:
- synthetic aperture telescope:
- synthetic field method (SFM): method of testing galaxy opacity
- synthetic photometry: deriving photometry-style data from spectroscopy
- synthetic spectrum: simulated spectrum, e.g., of a type of star
- System Requirements Review:
- MDR/SRR: planning step for a NASA mission
- systematic error: errors with non-random characteristics
- sigma (σ): indication of the confidence level of an experiment
- systematics:
- systemic redshift:
- systemic velocity: average velocity of grouped objects, such as a galaxy
- syzygy:
- opposition: positioning of two astronomical objects 180 degrees apart in the sky
- SZ:
- SZ Array:
- SZ effect:
- SZ/CMB-Pol:
- CCAT-prime (CCAT-p): planned 6-meter submillimeter telescope in Chile
- SZA:
- SZE:
Index