Term Index (G)
- G:
- G 268-38:
- LHS 1140: red dwarf with rocky planet in its habitable zone
- G 270-58:
- LHS 1140: red dwarf with rocky planet in its habitable zone
- G band: band of visible light around 5100 angstroms
- G dwarf:
- G numbers:
- G-APD:
- G-class:
- G-class star:
- G-CLEF: spectrograph on the GMT
- G-dwarf problem: lack of metal-poor G dwarfs in the Milky Way
- g-mode:
- G-type star (G): stars spectrally similar to the Sun
- G239-25: nearby red dwarf with brown dwarf companion
- G239-25AB:
- G239-25: nearby red dwarf with brown dwarf companion
- G395:
- GADGET:
- GADGET-2: an n-body/SPH simulation computer program
- GADGET-1:
- GADGET-2: an n-body/SPH simulation computer program
- GADGET-2: an n-body/SPH simulation computer program
- Gaia: 2010s astrometry survey satellite
- Gaia Celestial Reference Frame:
- Gaia Data Release 1:
- Gaia: 2010s astrometry survey satellite
- Gaia Data Release 2:
- Gaia: 2010s astrometry survey satellite
- Gaia DR1:
- Gaia: 2010s astrometry survey satellite
- Gaia DR2:
- Gaia: 2010s astrometry survey satellite
- Gaia-CRF:
- Gaia-ESO Survey:
- Gaia: 2010s astrometry survey satellite
- GAL:
- admittance: effect of atmospheric pressure on gravity
- double star designation: systems and format of double star designators
- Gal: gravimetry unit of the effect of a planet's gravity
- GALA:
- JUICE: mission to Jupiter in development
- Galactic All-sky Survey (GASS): HI survey of the Milky Way
- galactic anticenter: direction opposite the galactic center
- galactic archaeology: study of galaxy characteristics that reveal their past
- Galactic Archaeology with HERMES:
- GALAH: survey of Milky Way with an emphasis on old structures
- Galactic ASKAP Spectral Line Survey:
- galactic astronomy: astronomy confined to the Milky Way
- galactic binary: system of two object co-orbiting within the Milky Way
- galactic bulge: bulge of many stars in the center of the Milky Way
- bulge: denser group of stars within a larger group
- galactic center: region at the middle of the Milky Way
- MicroFUN (μFUN): observers following up on microlensing events in the galactic bulge
- galactic center: region at the middle of the Milky Way
- galactic center magnetar:
- galactic cirrus:
- galactic cluster:
- galaxy cluster (CL): large group of galaxies gravitationally-bound to the group
- open cluster (OC): group of stars within a galaxy apparently formed by a single cloud
- galactic coordinate system (GCS): celestial coordinate system system based upon the galactic plane
- galactic coordinates:
- galactic north: determination of the more northern direction of the Milky Way's axis
- galactic core:
- galactic corona:
- corona: plasma surrounding a star
- galactic halo: spherical region around a galaxy with gas, dark matter, etc.
- supershell: very large ISM shell-shaped region
- galactic cosmic rays:
- cosmic rays (CR): very-high-energy particles from beyond the solar system
- galactic disc:
- galactic disk: the "disk" portion of a disk galaxy
- galactic electron density: density of electrons in the ISM
- Galactic Emission Mapping (GEM): radio sky survey
- galactic equator:
- galactic filament:
- galactic fountain:
- galactic gamma-ray background:
- gamma rays (GR): electromagnetic radiation, wavelength 10 picometers and less
- galactic habitable zone:
- galactic halo: spherical region around a galaxy with gas, dark matter, etc.
- galactic jet:
- jet: stream of matter from an astronomical body
- galactic latitude:
- galactic longitude:
- galactic magnetic field:
- galactic main sequence:
- galactic north: determination of the more northern direction of the Milky Way's axis
- galactic north pole:
- galactic north: determination of the more northern direction of the Milky Way's axis
- galactic nucleus:
- Galactic O Star Catalog (GOSC,GOS): 2000s catalog of O-type stars
- Galactic O Star Spectral Survey:
- galactic period:
- galactic plane: plane in which the stars of the Milky Way reside
- Galactic Plane Infrared Polarization Survey:
- Mimir: multi-function near-infrared instrument on Perkins Telescope
- galactic planetary nebulae:
- galactic poles:
- galactic north: determination of the more northern direction of the Milky Way's axis
- galactic plane: plane in which the stars of the Milky Way reside
- galactic sheet:
- galactic south:
- galactic north: determination of the more northern direction of the Milky Way's axis
- galactic south pole:
- galactic north: determination of the more northern direction of the Milky Way's axis
- galactic spheroid:
- galactic halo: spherical region around a galaxy with gas, dark matter, etc.
- galactic stellar nucleus:
- galactic superwind:
- galactic tide: effect of one galaxy's gravity, such as on another galaxy
- tidal force: effect of a third body on the gravitational force between two bodies
- galactic void:
- void: empty spaces between large scale structures
- galactic wind: wind of charged particles out of some galaxies
- galactic year:
- GALAH: survey of Milky Way with an emphasis on old structures
- Galatea:
- galaxies:
- 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
- 6dF Galaxy Survey (6dFGS): UKST survey of galaxies in the southern sky
- active galactic nucleus (AGN): central region of a galaxy with extremely high luminosity
- AEGIS: survey study of distant galaxies
- ALFALFA: HI survey of many galaxies
- APM Galaxy Survey (APMUKS): 1990s survey of galaxies in southern sky
- Arakelian Catalog (Ark): 1970s list of small/bright galaxies
- Arecibo General Catalog (AGC): catalog of galaxies to support ALFALFA surveys
- Arp-Madore Catalog of Southern Peculiar Galaxies (AM): 1970s-1980s catalog from the UK Schmidt Survey
- Asiago Supernova Catalog (B/SN): 1999 catalog of known supernovae and their galaxies
- Atlas 3D: survey of local galaxies
- Atlas of Peculiar Galaxies (APG): 1960s catalog-book with photos
- bar: central feature of some spiral galaxies
- BDF: field used in search for distant galaxies
- BigBOSS: BOSS survey follow-on
- binary SMBH (BSMBH,SMBBH,SMBHB): co-orbiting supermassive black holes
- broad-line region (BLR): region in center of active galaxy where spectral lines are broad
- bulge: denser group of stars within a larger group
- Butcher-Oemler effect (BOE): observation of more blue galaxies at z > 0.3
- Caldwell Catalog: small catalog for amateur astronomers as an adjunct to the Messier Catalog
- CALIFA: spectroscopic map of 600 galaxies
- Canada-France Redshift Survey (CFRS): 1990s survey of galaxies to z = 1 to find associations of redshift to characteristics
- CARMA EDGE: CO survey of galaxies
- Catalog of Galaxies and Clusters of Galaxies (CGCG): list of galaxies/clusters assembled in 1960s
- Catalogue of Interacting Galaxies (VV): begun in the 1950s
- 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
- circumgalactic medium (CGM): gas surrounding a galaxy
- cold gas: gas cool enough to form galaxies and stars
- COLD GASS: survey of CO in nearby large galaxies
- color-color diagram (CCD): means of comparing characteristics of stars
- color-magnitude diagram (CMD,CM): graph plotting stars' color to luminosity
- conditional luminosity function (CLF): function characterizing luminosity of galaxies with a given halo mass
- conditional stellar mass function (CSMF): function characterizing galaxies within a halo of a given mass
- Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS): early universe survey by HST
- cosmic web: hypothesized structure of the dark matter throughout the universe
- dark matter: matter suggested by gravity in galaxies and galaxy clusters
- dark matter halo: hypothetical dark matter throughout and surrounding a galaxy
- David Dunlap Observatory Catalog (DDO): catalog of dwarf galaxies
- de Vaucouleurs' profile: relation between elliptical galaxy surface brightness and distance from center
- DECaLS: survey imaging part of SDSS footprint with DECam
- deep field (DF): survey field subject to lengthy observation to identify distant galaxies
- Deep Lens Survey (DLS): investigating mass distribution of the universe
- deep survey: survey using lengthy observation to identify distant galaxies
- DEEP2: redshift survey of 60,000 galaxies
- disk: rotating disk-shaped object such as disk galaxy or circumstellar disk
- dropout: means of identifying distant galaxies
- Duus-Newell catalog (DN): list of southern galaxies/clusters assembled in 1970s
- dwarf galaxy classification: terms for of dwarf galaxy types
- Dwingeloo Obscured Galaxy Survey (DOGS): radio survey of ZOA for 21-cm lines indicating galaxies
- effective radius (Re): radius of a galaxy within which 1/2 the light is emitted
- escape fraction: fraction of ionizing photons escaping a body
- ESO Nearby Abell Cluster Survey (ENACS): 1990s spectroscopy and photometry survey of galaxy clusters
- Extended Chandra Deep Field-South Survey (ECDFS): 1100 square arcminute X-ray survey
- Extended Groth Strip (EGS): region of sky searched for distant galaxies
- extragalactic astronomy: astronomy of other galaxies, galaxy clusters, AGNs, quasars, etc.
- Faber-Jackson relation (FJR): relation between elliptical galaxy luminosity and stellar velocity dispersion
- Faint Infrared Grism Survey (FIGS): survey to identify redshift of distant galaxies
- Fairall Galaxy List (Frl,Fairall): 1977 list of galaxies with bright nuclei
- Fanaroff-Riley classification: a classification of the radio characteristics of radio sources
- field: adjective meaning "in this field of view but unrelated"
- FIRE Simulations: high resolution simulation of galaxies
- fossil group: apparent remnant of a galaxy group
- FourStar Galaxy Evolution Survey (ZFOURGE,Z-FOURGE): infrared deep-survey to detect galaxies
- Freeman's law: all spiral galaxy's have the same central surface brightness
- fundamental plane: three-way relation between elliptical galaxy characteristics
- galactic archaeology: study of galaxy characteristics that reveal their past
- galactic disk: the "disk" portion of a disk galaxy
- galactic electron density: density of electrons in the ISM
- galactic halo: spherical region around a galaxy with gas, dark matter, etc.
- galactic tide: effect of one galaxy's gravity, such as on another galaxy
- galactic wind: wind of charged particles out of some galaxies
- galaxy age determination: methods of estimating a galaxy's age
- galaxy bias: degree to which galaxy density fails to correspond to dark matter density
- galaxy classification: morphological classification of galaxies
- galaxy cloud: substructure of a supercluster
- galaxy cluster (CL): large group of galaxies gravitationally-bound to the group
- galaxy environment: density and character of galaxies surroundings
- galaxy filament: thread-like formations of galaxies, 50 to 80 megaparsecs
- galaxy formation: modeled as collapsing clouds
- galaxy group: group of fifty or fewer gravitationally bound Milky-Way-sized galaxies
- galaxy harassment: frequent occurrences of small galaxies passing close to a galaxy
- galaxy main sequence: relation between galaxies' star formation and stellar mass
- galaxy merger: combination of galaxies upon collision
- galaxy power spectrum: a power spectrum describing the occurrence of galaxies in space
- galaxy SED: SED of a galaxy, sometimes synthesized from photometric surveys
- galaxy strangulation: galaxy star formation stopped by a lack of incoming gas
- galaxy subgroup: group of fifty or fewer gravitationally bound Milky-Way-sized galaxies
- Galaxy Zoo: crowdsourcing website to identify galaxy types from surveys
- 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
- Gini/M20: an automatable method of detecting whether a galaxy has recently merged
- globular cluster luminosity function (GCLF): distribution of brightness of globular clusters
- GOODS NICMOS Survey (GNS): survey with HST NICMOS instrument of galaxies in GOODS fields
- Great Debate: historical debate regarding the nature of galaxies
- halo abundance matching (HAM): method of comparing observed galaxies with cosmology models
- Hawaii K-band Galaxy Survey: near-infrared survey of a selection of fields
- Herschel Redshift Survey (HeRS): 70 square-degree survey of galaxies redshifted 1.8 to 3.5
- hierarchical assembly of galaxies: development of large galaxies by combining small ones
- Holmberg radius (RH,RHO): a measure of size of galaxy based on surface brightness
- 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 diagram: diagram comparing redshift with distance
- Hubble Ultra-Deep Field (HUDF): extremely detailed HST image of a small region of space
- intergalactic medium (IGM): matter between galaxies
- ITEP-SAI Supernova Light Curve Catalogue: online catalog
- Jeans equations: relating the motion of stars to the surrounding gravitational field
- JINGLE: survey of dust and gas in galaxies
- Kiso Survey of Ultraviolet Excess Galaxies (KUG): 1980 Japanese survey
- KMOS3D: survey of galaxies before to after peak star formation
- Kormendy Relation: relation between elliptical galaxy luminosity surface brightness
- Las Campanas Redshift Survey (LCRS): 1990s survey of galaxies out to z = 0.2
- Limber approximation: formula approximating the density of galaxies in some direction
- LINER: galaxy nucleus emitting spectral lines for ionized and neutral atoms
- luminosity function (LF): function giving number of stars or galaxies at different luminosities
- M-sigma relation: relation between galaxy center's velocity dispersion and SMBH mass
- Magellanic clouds (MC): two nearby galaxies
- mass transport: transfer of mass from one part of a body/disk to another
- Medium Deep Survey (MDS): survey to find galaxies in HST WFPC2 images
- Meier paradox: mysterious decline in number of radio galaxy jets
- Messier Catalog (M): catalog of astronomical objects to avoid when looking for comets
- MIGHTEE: radio survey of four established deep fields
- Milky Way subgroup: the Milky Way and its satellites
- Millennium Galaxy Catalogue (MGC): 2000s catalog of 10,000 galaxies
- MOJAVE: program to monitor AGN jet radio brightness and polarization
- molecular cloud turbulence: observed turbulence in molecular clouds
- Morgan classification: classification of galaxies by stellar spectrum and morphology
- Morphological Catalogue of Galaxies (MCG): 1960s catalog from Palomar plates
- morphology-density relation: a galaxy is more likely to be elliptical if surrounded by galaxies
- moving group: observed group of stars with similar motion
- Munich Near-Infrared Cluster Survey (MUNICS): 1990s-2000s galaxy cluster survey
- NASA/IPAC Extragalactic Database (NED): a database of galaxies and other objects outside the Milky Way
- New General Catalogue (NGC): 1888 catalog of galaxies, star clusters, and other nebulae
- NOAO Deep Wide-field Survey (NDWFS): survey investigating large scale structure of the universe
- OB association: stellar association with O or B class stars
- open cluster (OC): group of stars within a galaxy apparently formed by a single cloud
- Palomar Four-filter Survey (PC): Hale telescope survey aimed at discovering high-redshift quasars
- Parkes HI Zone of Avoidance Survey (HIZOA): radio survey to identify galaxies hidden by the zone of avoidance
- PCA analysis: an automatable method of determining galaxy morphology
- peak star-formation epoch: around 10 billion years ago when star formation peaked
- PHANGS: set of surveys of nearby galaxies
- planetary nebula luminosity function (PNLF): model used in distance estimation
- Polar-ring Catalog (PRC): 1990 catalog of polar-ring galaxies
- PRIMUS: spectrographic survey of galaxies out to redshift 1
- Principal Galaxies Catalog (PGC): modern catalog of more than 70k galaxies
- protogalaxy: gas cloud forming a galaxy
- pseudobulge: like a galaxy bulge only flatter
- quasar (QSO): distant, bright object that appears something like a star
- Radio Galaxy Zoo (RGZ): crowd-sourced classification of radio galaxies
- RASS/Green Bank Catalog (RGB,RASSGB): combined list of radio galaxies from Rosat and Green Bank surveys
- red and dead: description of a galaxy with old stars and no star formation
- Reference Catalogue of Bright Galaxies (RC,RC1): series of catalogs of nearby galaxies
- Roma-BZCAT: 2008 catalog of blazars
- rotation curve: function mapping distance from galaxy center to orbital speed of stars
- Sérsic profile: model of the relative surface brightness across a galaxy
- Scott effect: bias toward finding clusters that have bright galaxies
- Second Byurakan Survey (SBS): 1970s-1990s survey of galaxies and quasars
- Shapley-Ames Catalog (SAC): 1932 catalog of contemporary data on 1249 galaxies
- SHARDS: GTC survey in GOODS-N field for quenched galaxies at z 1-2.3
- SINS: near-infrared study of distant luminous galaxies
- spiral arm: long, winding visible structure within a spiral galaxy
- spiral density wave: spiral structure that can form in disks
- Spitzer Extended Deep Survey (SEDS): survey of galaxy mass and black holes through life of the universe
- Spitzer HETDEX Exploratory Large Area Survey (SHELA): Spitzer-based survey of galaxies
- 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 rate (SFR): rate at which material such as gas is turned into stars
- star-formation rate stellar-mass ratio: ratio between a galaxy's stellar mass and its SF rate
- STARSMOG: survey of dust in galaxies
- stellar association: like a large open cluster but even less tightly bound
- stellar cluster (SC): group of stars apparently formed by a single cloud
- stellar dynamics: stars' gravitational interaction
- stellar nucleus: group of many stars at the center of a galaxy
- stellar overdensity: portion of galactic halo with more stars than normal
- stellar population synthesis (SPS): using spectral characteristics of galaxies to characterize their stellar populations
- 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
- submillimeter galaxy designator: designation system of submillimeter galaxies
- SuperCOSMOS Sky Survey (SSS): survey of stars and galaxies from legacy plates
- supermassive black hole (SMBH): black hole with a mass of millions to billions of solar masses
- surface brightness fluctuation (SBF): apparent indication of an elliptical galaxy's distance
- surface brightness profile: curve of a galaxy's brightness from center to edge
- systemic velocity: average velocity of grouped objects, such as a galaxy
- T association: stellar association with T-Tauri stars
- The Survey for Ionization in Neutral Gas Galaxies (SINGG): survey of H-alpha in galaxies found through the HI line
- tidal arm: arm of gas and potentially stars leading from a galaxy
- TiNy Titans (TNT): study of dwarf galaxy pairs
- tip of the red-giant branch (TRGB): using a galaxy's maximum RGB brightness as a standard candle
- Toomre sequence: model relating galaxy mergers to observation
- Tully-Fisher relation (TFR): relation between spiral galaxy luminosity and line width
- Two Micron All-sky Survey (2MASS): near-infrared survey of both hemispheres
- Uppsala General Catalogue (UGC): 1973 catalog of galaxies visible from northern hemisphere
- van den Bergh galaxy classification: galaxy classification variant including luminosity
- VIMOS Public Extragalactic Redshift Survey (VIPERS): spectrographic redshift survey of 80,000 galaxies
- Virgo Cluster Catalog (VCC): 1980s catalog of 2000 galaxies
- warp: bend in the otherwise=flat disk of a galaxy
- WiggleZ: survey aimed at mapping dark energy
- WINGS: all-sky survey investigating known galaxy clusters
- WISeREP: interactive catalog of supernovae
- X-ray luminosity function (XLF): maps X-ray luminosities to count of such sources
- Galaxies with High Surface Brightness:
- GALAXY:
- galaxy age determination: methods of estimating a galaxy's age
- Galaxy and Mass Assembly Survey:
- GAMA: galaxy spectroscopy survey to roughly 1 Mpc
- galaxy bar:
- bar: central feature of some spiral galaxies
- galaxy bias: degree to which galaxy density fails to correspond to dark matter density
- galaxy bimodality:
- galaxy: gravitationally-bound group of stars
- galaxy classification: morphological classification of galaxies
- galaxy cloud: substructure of a supercluster
- galaxy cluster (CL): large group of galaxies gravitationally-bound to the group
- galaxy clusters:
- galaxy collision:
- galactic tide: effect of one galaxy's gravity, such as on another galaxy
- galaxy color magnitude diagram:
- galaxy diagram:
- galaxy environment: density and character of galaxies surroundings
- Galaxy Evolution Explorer (GALEX): observatory-satellite with 50-cm ultraviolet telescope
- galaxy feedback:
- galaxy filament: thread-like formations of galaxies, 50 to 80 megaparsecs
- galaxy formation: modeled as collapsing clouds
- galaxy group: group of fifty or fewer gravitationally bound Milky-Way-sized galaxies
- galaxy groups:
- galaxy subgroup: group of fifty or fewer gravitationally bound Milky-Way-sized galaxies
- galaxy harassment: frequent occurrences of small galaxies passing close to a galaxy
- galaxy interaction:
- galactic tide: effect of one galaxy's gravity, such as on another galaxy
- galaxy harassment: frequent occurrences of small galaxies passing close to a galaxy
- galaxy merger: combination of galaxies upon collision
- tidal tail: string of mass ejected by a tidal forces in a neutron star merger
- galaxy luminosity class:
- galaxy luminosity function:
- luminosity function (LF): function giving number of stars or galaxies at different luminosities
- galaxy main sequence: relation between galaxies' star formation and stellar mass
- galaxy merger: combination of galaxies upon collision
- galactic tide: effect of one galaxy's gravity, such as on another galaxy
- galaxy merger mass ratio:
- galaxy merger timescale:
- galaxy morphology:
- galaxy nucleus:
- active galactic nucleus (AGN): central region of a galaxy with extremely high luminosity
- broad-line region (BLR): region in center of active galaxy where spectral lines are broad
- galactic center: region at the middle of the Milky Way
- LINER: galaxy nucleus emitting spectral lines for ionized and neutral atoms
- galaxy power spectrum: a power spectrum describing the occurrence of galaxies in space
- galaxy quenching:
- galaxy rotation curve:
- rotation curve: function mapping distance from galaxy center to orbital speed of stars
- galaxy SED: SED of a galaxy, sometimes synthesized from photometric surveys
- galaxy sheet:
- galaxy spectral energy distribution:
- galaxy SED: SED of a galaxy, sometimes synthesized from photometric surveys
- galaxy strangulation: galaxy star formation stopped by a lack of incoming gas
- galaxy subgroup: group of fifty or fewer gravitationally bound Milky-Way-sized galaxies
- galaxy supercluster:
- galaxy type:
- galaxy wall:
- galaxy warp:
- warp: bend in the otherwise=flat disk of a galaxy
- Galaxy Zoo: crowdsourcing website to identify galaxy types from surveys
- Galaxy Zoo 2 (GZ2): crowd-sourced classification of hundreds of thousands of galaxies
- Gale Crater:
- Galerkin method:
- GALEX:
- GALEX Arecibo SDSS Survey (GASS): HI survey of many galaxies
- GALEX ASC:
- GALFA-HI:
- Galilean frame of reference:
- Galilean Moons:
- Jupiter: largest planet in the solar system
- moon: a planet's natural satellite, such as Earth's
- Galilean relativity:
- relativity: physics models accommodating the constancy of the speed of light
- Galilean transform:
- relativity: physics models accommodating the constancy of the speed of light
- Galilean transformation:
- GALILEO:
- Gal: gravimetry unit of the effect of a planet's gravity
- Galileo: circa 1990s space mission to Jupiter
- Ganymede: well-known Jupiter moon
- Io: well-known Jupiter moon
- Parkes Observatory: Australian large single-dish radio telescope
- Galileo Europa Mission:
- Galileo: circa 1990s space mission to Jupiter
- Galileo Millennium Mission:
- Galileo: circa 1990s space mission to Jupiter
- Galileo National Telescope:
- Galileo Observatory: infrared observatory-plane in the early 1970s
- GalMC:
- GAMA: galaxy spectroscopy survey to roughly 1 Mpc
- Gamma Cassiopeiae variable:
- Gamma Leporis A:
- F-type star (F): spectral class of star a bit hotter than then Sun
- gamma rays (GR): electromagnetic radiation, wavelength 10 picometers and less
- gamma-ray astronomy:
- gamma rays (GR): electromagnetic radiation, wavelength 10 picometers and less
- gamma-ray burst (GRB): short flashes of gamma rays apparently from outside our galaxy
- gamma-ray burst (GRB): short flashes of gamma rays apparently from outside our galaxy
- gamma rays (GR): electromagnetic radiation, wavelength 10 picometers and less
- gamma-ray burst progenitor:
- gamma-ray burst (GRB): short flashes of gamma rays apparently from outside our galaxy
- gamma-ray burst source:
- gamma-ray burst (GRB): short flashes of gamma rays apparently from outside our galaxy
- gamma-ray bursts:
- Gamma-ray Large Area Space Telescope:
- Fermi (FGST,GLAST): satellite for studying gamma rays
- gamma-ray source:
- gamma rays (GR): electromagnetic radiation, wavelength 10 picometers and less
- Gamow factor:
- Gamow peak: relative speed most likely to cause atoms to fuse within a gas
- Gamow peak: relative speed most likely to cause atoms to fuse within a gas
- Ganymede: well-known Jupiter moon
- gas:
- gas blowout:
- gas cloud:
- gas constant:
- gas disk migration:
- gas dwarf:
- gas planet: planet made largely of gas
- mini-Neptune: planet with characteristics a bit like Earth but more like Neptune
- super-Earth: exoplanet more massive than Earth but substantially less than Neptune
- gas excitation:
- gas extinction:
- extinction: the absence of any radiation from an astronomical object because all is absorbed or scattered
- gas flow: dynamics of gas, plasma, i.e., compressible fluids
- gas fraction: fraction of a galaxy or cluster consisting of gas
- gas fraction estimation: methods of estimating various amounts of gas in galaxies
- gas giant: large planet made largely of gas
- gas mass fraction:
- gas fraction: fraction of a galaxy or cluster consisting of gas
- gas planet: planet made largely of gas
- gas streamer: stream of gas
- gas tail:
- comet: Sun-orbiting object with coma and possible tail
- gas torus:
- Io: well-known Jupiter moon
- gas-to-core ratio:
- gas-to-dust ratio (GDR): mass ratio of gas to dust, such as within a SF region
- gaseous corona:
- gaseous envelope:
- GASKAP:
- Gasoline:
- GASS:
- GAT:
- gauge boson:
- Gaunt factor:
- gauss (G,Gs): measurement of magnetic field β
- Gauss's law:
- Gaussian:
- Gaussian distribution:
- Gaussian function: function producing the bell curve
- Gaussian profile:
- GB:
- GB-BL:
- GB300:
- GB6:
- GBD:
- Ginga: 1980s Japanese space X-ray telescope
- GBM:
- Fermi (FGST,GLAST): satellite for studying gamma rays
- GBO:
- GBS:
- gamma-ray burst (GRB): short flashes of gamma rays apparently from outside our galaxy
- GBT:
- Breakthrough Listen (BL): SETI survey using GBT and Parkes Observatory
- DeGaS-MC: GBT survey of potential star formation regions in the Magellanic Clouds
- Green Bank Telescope (GBT,GB): West Virginia large radio telescope
- GUPPI: radio-telescope back-end aimed at processing pulsar data
- GC:
- GC bimodality:
- GC magnetar:
- GC system:
- GC/MS:
- Cassini: explorer spacecraft sent to Saturn
- GCAS:
- GCC:
- GCGSS:
- GCIRS:
- GCLF:
- GCM:
- GCMS:
- Cassini: explorer spacecraft sent to Saturn
- GCR:
- cosmic rays (CR): very-high-energy particles from beyond the solar system
- gas planet: planet made largely of gas
- GCRV:
- GCS:
- GCTP:
- GCVS:
- GD:
- GD-1: stellar stream formed by globular cluster
- GDR:
- GDS:
- Neptune: outer-most solar system planet
- GDS-89:
- Neptune: outer-most solar system planet
- GDSCC:
- Geiger mode:
- Geiger-avalanche photodiode (G-APD,SPAD): type of solid state photon sensor
- Geiger-Müller tube:
- GEM:
- GEM Telescope:
- Gemini Camera:
- Gemini North:
- Gemini Observatory: pair of telescopes in Hawaii and Chile
- Gemini Planet Imager (GPI): infrared instrument to overcome signal noise imaging exoplanets
- Gemini South:
- GeMS:
- General Automatic Luminosity And X-Y:
- General Catalog of Trigonometric Parallaxes (GCTP): 1950s star catalog with later updates
- General Catalog of Trigonometric Stellar Parallaxes:
- General Catalogue of Double Stars Within 121° of the North Pole:
- General Catalogue of Nebulae and Clusters of Stars:
- General Catalogue of Stellar Radial Velocities (GCRV): 1950s century catalog of 15000 stars with their 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
- general circulation model (GCM): climate model of a planet's atmosphere or ocean
- general relativistic effects:
- general relativity (GR): formula relating gravity, space, time, and mass
- Generalized NFW profile:
- GEO project:
- GEO600: ground-based gravitational-wave detector in Germany
- GEO600: ground-based gravitational-wave detector in Germany
- Geocentric Coordinate Time:
- terrestrial time (TT): current measure of time for astronomical observations on Earth
- geocentric gravitational constant:
- geocentric system:
- geochemistry: the chemistry of the Earth, planets, and moons
- geodesic: equivalent to a straight line in curved space
- GEODSS:
- geodynamo:
- dynamo: mechanism for generating magnetic fields around astronomical bodies
- geology:
- basalt: an igneous rock type that shows rapid cooling
- bathymetry: study and measurement of sea depths
- bulk silicate earth (BSE): the early overall composition of the silicate part of Earth
- CIG: initiative to produce Earth-science software
- crustal magnetism: magnetic fields independent of a world's core magnetic field
- crustal plates: sections of the Earth's crust that move
- equilibrium condensation model: chemical model explaining solar system planet abundances
- geochemistry: the chemistry of the Earth, planets, and moons
- geosignature: geological sign of consequences of life
- magma ocean: presumed to occur early in Earth history and potentially on exoplanets
- paleomagnetism: ancient magnetic fields and their characteristics
- permeability (κ,k): ability of a material to allow fluids to pass through it
- pingo: hill formed of ice
- planetary differentiation: stratification of the materials making up a planet
- polygonal ground: crack pattern in ground forming polygons due to freezing
- regolith: loose solid material covering a planet's solid rock
- seismic waves: waves broadcast through Earth from earthquakes
- siderophile: material that dissolves in molten iron
- silicate: type of compound including silicon and oxygen
- stratigraphy: study of rock layering
- tide: effect of Moon's gravity on Earth's seas, etc.
- weathering: changes in surface due to contact with atmosphere
- geomagnetic storm: disturbance in Earth's magnetosphere
- geometric albedo:
- albedo: measure of reflectance
- geometric delay:
- correlator: unit that interferes wave signals for interferometry
- geometrical theory of diffraction:
- geometry:
- geophysics:
- geopotential model:
- geoseismology:
- normal mode: sinusoidal oscillation, such as in seismology
- geosignature: geological sign of consequences of life
- geostationary:
- orbital speed: speed of an orbiting body around the barycenter of a system
- geostationary orbit:
- synchronous orbit: orbit with angular velocity matching the rotation of the orbited body
- geostrophic balance:
- thermal wind: wind from pressure and the Coriolis force varying with altitude
- geostrophic wind:
- thermal wind: wind from pressure and the Coriolis force varying with altitude
- geosynchronous orbit:
- synchronous orbit: orbit with angular velocity matching the rotation of the orbited body
- GERLUMPH: hardware/software simulator of lensing light curves
- German:
- eROSITA: Russian/German space X-ray telescope launched in 2019
- ROSAT: 1990s German space X-ray telescope
- Spektr-RG (SRG, SXG): Russian-German X-ray observatory launched in 2019
- German Aerospace Center:
- SOFIA: aircraft-based infrared observatory
- germanium:
- r-process: synthesization of elements through neutron capture faster than beta decay
- germanium immersion grating:
- Germany:
- GES:
- Gaia: 2010s astrometry survey satellite
- GEXPAC:
- GG Tau: much-studied quadruple star system
- GG Tauri:
- GG Tau: much-studied quadruple star system
- GGM:
- Goddard gravity model (GGM): gravity model produced by Goddard Space Flight Center
- MMX: Japanese probe to bring back a sample of a Martian moon
- GH:
- ghost image:
- stray light: unintended light reaching a telescope's sensors
- GHRS:
- GHz peaked spectrum:
- radio source (RS): something in the sky generating radio signal
- GI:
- GI dynamo:
- dynamo: mechanism for generating magnetic fields around astronomical bodies
- GI2T: optical interferometer in France
- GIADA:
- Rosetta: space probe that visited a comet
- GIANO:
- giant elliptical galaxy: very large elliptical galaxy generally at a galaxy cluster's center
- giant impact:
- impact: collision of one solid body with another
- giant impacts:
- Giant Magellan Telescope (GMT): 24.5 meter telescope under construction
- giant magnetar flare:
- magnetar: neutron star with a strong magnetic field
- Giant Metrewave Radio Telescope (GMRT): large radio interferometer in India
- giant molecular cloud (GMC): interstellar gas cloud with molecules, thousands of solar masses
- giant planet: planet of more than 10 Earth masses
- giant planet formation: process by which giant planets form
- giant planets:
- giant pulse:
- giant radio galaxy:
- giant radio source:
- radio source (RS): something in the sky generating radio signal
- Giant Segmented Mirror Telescope (GSMT): concept for an extremely large telescope
- giant star: star larger than main sequence stars
- Arcturus: fourth brightest star in the sky
- Beta Centauri: second brightest star in Centaurus
- Betelgeuse: second brightest star in constellation Orion
- Canopus: second brightest star in the sky
- giant stars:
- giant-impact hypothesis:
- impact: collision of one solid body with another
- moon: a planet's natural satellite, such as Earth's
- Moon formation: process by which the Moon and other moons formed
- GIC:
- Giclas:
- GIG:
- gigayear (Gy,Gyr): a billion years
- GIMI:
- ARGOS: 1999 technology-research satellite
- GIMIC:
- EAGLE: simulation of galaxy formation and evolution
- GIMP:
- WIMP: proposed particle comprising dark matter
- Ginga: 1980s Japanese space X-ray telescope
- Gini:
- Gini/M20: an automatable method of detecting whether a galaxy has recently merged
- Gini-M20:
- Gini/M20: an automatable method of detecting whether a galaxy has recently merged
- Gini/M20: an automatable method of detecting whether a galaxy has recently merged
- GIO:
- Giotto: 1980s space mission carrying out a Comet Halley flyby
- Giotto Extended Mission:
- Giotto: 1980s space mission carrying out a Comet Halley flyby
- GIRAFFE:
- GIS:
- ASCA: 1990s Japanese space X-ray telescope
- GISMO: 2 mm bolometer camera on IRAM 30 m telescope
- GISS GCM ModelE:
- ROCKE-3D: Rocky-planet-oriented general circulation model
- GitHub:
- GIZMO:
- GJ:
- GJ 1132:
- GJ 1132 b: Earth-like extrasolar planet discovered in 2015
- GJ 1132 b: Earth-like extrasolar planet discovered in 2015
- GJ 1214:
- GJ 1214 b: super-Earth extrasolar planet discovered in 2009
- GJ 1214 b: super-Earth extrasolar planet discovered in 2009
- GJ 3053:
- LHS 1140: red dwarf with rocky planet in its habitable zone
- GJ 436:
- GJ 436 b:
- GK dwarf:
- Gl:
- GLAS:
- GLAST:
- Fermi (FGST,GLAST): satellite for studying gamma rays
- GLE:
- Gliese:
- Gliese 1132:
- GJ 1132 b: Earth-like extrasolar planet discovered in 2015
- Gliese 1132 b:
- GJ 1132 b: Earth-like extrasolar planet discovered in 2015
- Gliese 1214:
- GJ 1214 b: super-Earth extrasolar planet discovered in 2009
- Gliese 1214 b:
- GJ 1214 b: super-Earth extrasolar planet discovered in 2009
- Gliese 191:
- Gliese 388:
- Gliese 411:
- Gliese 436:
- Gliese 436 b (GJ 436 b): hot Neptune found in 2004
- Gliese 581:
- M-type star (M): spectral class of star with a temperature in the vicinity of 2500 K
- Gliese 65:
- 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
- GLIMPSE:
- glitch:
- P-Pdot diagram: diagram comparing the rotation and the slowing of pulsars
- pulsar (PSR): type of astronomical body with EMR in regular cycles of seconds or less
- global astrometry:
- astrometry: precise measurement of the position and movement of stars
- global climate model:
- Global Microlensing Alert Network:
- GMAN: collaboration to alert on microlensing transients
- globular cluster (GC): spherical group of stars orbiting a galaxy
- globular cluster bimodality:
- globular cluster candidate:
- globular cluster luminosity function (GCLF): distribution of brightness of globular clusters
- luminosity function (LF): function giving number of stars or galaxies at different luminosities
- globular cluster specific frequency:
- globular cluster system:
- globular clusters:
- GLOWS:
- IMAP: future solar science probe
- GLP:
- GLT:
- Glue: visualization software good for astrophysical data
- gluino:
- supersymmetry (SUSY): extension to standard model of particle physics
- gluon:
- particle: very small thing
- quark: type of elementary particle incorporated in protons and neutrons
- standard model: model of elementary particles including quarks
- supersymmetry (SUSY): extension to standard model of particle physics
- Gly:
- glycine (Gly,G): smallest of the twenty common amino acids
- light-year (ly): distance that light travels in a year
- glycine (Gly,G): smallest of the twenty common amino acids
- GM:
- GMACS:
- GMAN: collaboration to alert on microlensing transients
- Gmb:
- GMC:
- GMF:
- GMM:
- GMOS:
- GMRT:
- GMT:
- GMT - CfA Large Earth Finder:
- G-CLEF: spectrograph on the GMT
- GMT-consortium Large Earth Finder:
- G-CLEF: spectrograph on the GMT
- GMTIFS:
- GMTNIRS:
- GN:
- GNFW profile:
- GNIRS:
- GNS:
- GNT:
- GO:
- guest observer (GO): non-affiliated researcher welcomed to use an observatory
- GO program:
- guest observer (GO): non-affiliated researcher welcomed to use an observatory
- GOBELINS:
- Goddard Earth Gravity Model:
- Goddard gravitational model:
- Goddard gravity model (GGM): gravity model produced by Goddard Space Flight Center
- Goddard High Resolution Spectrograph:
- HRS: high resolution spectrography
- Goddard IRAM Superconducting Two Millimeter Camera:
- GISMO: 2 mm bolometer camera on IRAM 30 m telescope
- Goddard Lunar Gravity Model:
- Goddard Mars Gravity Model:
- Goddard Mars Model:
- Goddard Space Flight Center (GSFC): NASA space research laboratory near Washington D.C.
- Godunov scheme: computational fluid dynamics method
- Godunov's scheme:
- Goldilocks zone:
- Goldstone Deep Space Communications Complex:
- GOLF:
- Goodman HST:
- SOAR: 4.1 m reflector telescope in Chile
- 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
- GOODS-N:
- GOODS: survey combining data from different sources on very distant objects
- GOODS-North:
- GOODS: survey combining data from different sources on very distant objects
- GOODS-S:
- GOODS: survey combining data from different sources on very distant objects
- GOODS-South:
- GOODS: survey combining data from different sources on very distant objects
- GoreSat:
- GOS:
- GOSC:
- GOSSS:
- Gould Belt:
- Gould designation:
- Gould's Belt: ring of stars around the sky
- Gould's Belt Distances Survey (GOBELINS): survey of parallax distances to Gould's Belt YSOs
- GP:
- Gpc:
- GPI:
- GPIPS:
- Mimir: multi-function near-infrared instrument on Perkins Telescope
- GPR:
- radar: probe based on reflecting radio waves
- Tianwen-1 (TW-1): Mars rover/orbiter mission currently orbiting Mars
- GPS:
- radio source (RS): something in the sky generating radio signal
- time dilation: relativity's ability to make time differ for different objects
- UKIDSS: five-part infrared survey using UKIRT
- GPU:
- GERLUMPH: hardware/software simulator of lensing light curves
- GPU-Enabled, High-Resolution, cosmological Microlensing parameter survey:
- GERLUMPH: hardware/software simulator of lensing light curves
- GR:
- GR*:
- GR1D: core collapse supernova simulation in 1D with GR
- GRACES:
- gradient:
- GRAIL: 2011 NASA lunar orbiters to collect gravity data
- GRAIL A:
- GRAIL: 2011 NASA lunar orbiters to collect gravity data
- GRAIL B:
- GRAIL: 2011 NASA lunar orbiters to collect gravity data
- grain:
- cosmic dust: cosmic dust is dust in space such as interstellar dust
- grams per mole:
- Gran Tecan:
- Gran Telescopio Canarias (GTC): 10.4 meter telescope in the Canary Islands
- Gran Telescopio Milimétrico:
- GRANAT: observatory-satellite for detecting gamma rays and X-rays
- GRaND:
- Dawn: explorer spacecraft sent to asteroids Vesta and Ceres
- grand design spiral galaxy: spiral galaxy with two just two arms that are well-defined
- Grand Interféromètre a 2 Télescopes:
- GI2T: optical interferometer in France
- Grand Unified Theory:
- electroweak: single conception including both electromagnetic and weak forces
- strong force: force that holds quarks and nuclei together
- symmetry breaking: loss of symmetry, such as due to loss of stability in a regime change
- Theory of Everything (TOE): single law explaining the four forces of nature
- grandmoon:
- granulation:
- Sun: star at center of solar system
- granule:
- graph:
- error bar: feature of a graph to indicate accuracy
- graph theory:
- dendrogram: diagram of a "tree", i.e., of a graph without cycles
- graphic information processor:
- GERLUMPH: hardware/software simulator of lensing light curves
- grating: spectrometer component
- grism: combination of a grating and a prism
- grating prism:
- grism: combination of a grating and a prism
- grating spectrometer:
- gravimeter:
- gravimetry: measurement of gravity's strength
- admittance: effect of atmospheric pressure on gravity
- Bouguer anomaly: gravity's local variation after compensating for altitude and landforms
- free-air anomaly: gravity's local variation after compensating for altitude
- gravity anomaly: difference between measured gravity and that predicted by a model
- gravitation:
- gravitational binding energy:
- gravitational collapse: shrinking of an object from gravitational force
- gravitational collapse energy:
- gravitational constant (G): indicates how much pull between two masses
- Gravitational European Observatory:
- GEO600: ground-based gravitational-wave detector in Germany
- gravitational field: gravitational force as distributed over a space
- gravitational harmonics:
- J2: geopotential coefficient regarding a planet's oblateness
- gravitational instability (GI): instability due to gravity
- gravitational instability dynamo:
- dynamo: mechanism for generating magnetic fields around astronomical bodies
- gravitational instability model: model for the formation of giant planets
- gravitational lens:
- gravitational lensing: focusing electromagnetic radiation by gravitational force
- gravitational locking:
- gravitational mass:
- mass: object's quality that determines the effects of forces and gravity
- gravitational microlensing: gravitational lensing by "small" objects such as individual stars and planets
- gravitational model:
- gravitational moment:
- J2: geopotential coefficient regarding a planet's oblateness
- gravitational nanolensing:
- gravitational potential (Φ): conceptual field indicating the strength of gravity at each point
- gravitational potential energy:
- gravitational potential model: mathematical model of an astronomical body's gravitational field
- gravitational primary:
- primary: central body of a system such as the Sun in the solar system
- gravitational pumping:
- gravitational quadrupole radiation:
- gravitational radiation:
- gravitational radius:
- gravitational redshift: redshift due to GR effects of gravity
- gravitational scattering:
- gravitational separation:
- gravitational singularity: point where density and gravity reach infinity
- gravitational slingshot:
- gravitational sounding:
- gravity sounding: measuring a planet's gravitation field by study of nearby probe flights
- gravitational spectrum:
- J2: geopotential coefficient regarding a planet's oblateness
- gravitational time delay:
- gravitational time dilation:
- time dilation: relativity's ability to make time differ for different objects
- gravitational wave (GW): ripples in the curvature of spacetime propagating as a wave
- gravitational wave astronomy:
- gravitational wave background (GWB): combination of weak gravitational waves such as from distant sources
- gravitational wave detection:
- gravitational wave (GW): ripples in the curvature of spacetime propagating as a wave
- GW detection (GW): observed gravitational wave signal recognizable as an astronomical event
- gravitational wave detector:
- gravitational wave event:
- gravitational wave spectrum: various frequencies of gravitational waves
- gravitational wave strain (h): a measure of the magnitude of a gravitational wave
- gravitational waves:
- gravitational well:
- gravitational-wave detector: device to detect gravitational waves
- gravitational-wave memory: a gravitational wave that does not return
- gravitational-wave observatory:
- gravitationally bound: description of objects kept together by gravity
- gravitationally interacting massive particle:
- WIMP: proposed particle comprising dark matter
- gravithermal catastrophe:
- gravitino:
- supergravity (SUGRA): combination of general relativity and supersymmetry
- gravitometer:
- graviton: quantum of gravity
- supergravity (SUGRA): combination of general relativity and supersymmetry
- gravitoturbulence:
- GRAVITY:
- gravity anomaly: difference between measured gravity and that predicted by a model
- Bouguer anomaly: gravity's local variation after compensating for altitude and landforms
- free-air anomaly: gravity's local variation after compensating for altitude
- gravimetry: measurement of gravity's strength
- gravity assist: method of boosting the speed of a spacecraft
- Venus: second inner-most planet in the solar system
- gravity crystal:
- gravity harmonics:
- J2: geopotential coefficient regarding a planet's oblateness
- gravity model:
- Gravity Recovery and Interior Laboratory:
- GRAIL: 2011 NASA lunar orbiters to collect gravity data
- gravity sounding: measuring a planet's gravitation field by study of nearby probe flights
- gravity spectrum:
- J2: geopotential coefficient regarding a planet's oblateness
- gravity traverse:
- gravity wave: wave in fluid where restoring force is gravity
- GRAVITY+:
- gravity-sensitive spectral lines:
- gray atmosphere: a model atmosphere whose opacity does not depend upon wavelength
- gray body: ideal object that reflects the same fraction of light at any wavelength
- graybody:
- gray body: ideal object that reflects the same fraction of light at any wavelength
- grazing angle:
- grazing incidence optics (GIO): optics that avoid large changes to the angle of rays
- grazing incident optics:
- NICER: space X-ray mission specifically to view neutron stars
- NuSTAR: space telescope for high-energy X-rays
- Wolter telescope: reflector telescope using only shallow-angle reflections
- GRB:
- gamma rays (GR): electromagnetic radiation, wavelength 10 picometers and less
- gamma-ray burst (GRB): short flashes of gamma rays apparently from outside our galaxy
- Ulysses: space mission to observe the Sun from off the ecliptic
- GRB 170817A:
- GW170817: 2017 gravitational wave detection from a neutron star merger
- GRB afterglow:
- gamma-ray burst (GRB): short flashes of gamma rays apparently from outside our galaxy
- GRB lightcurve:
- gamma-ray burst (GRB): short flashes of gamma rays apparently from outside our galaxy
- GRB optical transient:
- gamma-ray burst (GRB): short flashes of gamma rays apparently from outside our galaxy
- GRB progenitor:
- gamma-ray burst (GRB): short flashes of gamma rays apparently from outside our galaxy
- GRBs:
- mass extinction: event in which many species went extinct
- TAROT: network of telescopes to catch GRB optical counterparts
- GRE:
- Giotto: 1980s space mission carrying out a Comet Halley flyby
- GREAT:
- SOFIA: aircraft-based infrared observatory
- Great Andromeda Nebula:
- Andromeda (M31): spiral galaxy in the Local Group
- nebula: cloud of dust and gas
- Great Attractor: gravity anomaly at the center of our supercluster
- Great Blue Spot:
- great circle:
- meridian: circle around the Earth passing through both poles
- Great Dark Spot:
- Neptune: outer-most solar system planet
- Great Debate: historical debate regarding the nature of galaxies
- Great Observatories Origins Deep Survey:
- GOODS: survey combining data from different sources on very distant objects
- Great Red Spot:
- Jupiter: largest planet in the solar system
- Great Void:
- void: empty spaces between large scale structures
- Great Wall: large slab of galaxies
- green:
- G band: band of visible light around 5100 angstroms
- Green Bank 140 Foot Telescope: West Virginia radio telescope
- Green Bank 300ft Telescope (GB300): former large radio telescope at Green Bank
- Green Bank 6-cm Radio Source Catalog (GB6): catalog of from 1980s northern-hemisphere radio survey
- Green Bank 90m Telescope:
- Green Bank 91m Telescope:
- Green Bank Observatory (GBO): radio observatory in West Virginia including GBT
- Green Bank Telescope (GBT,GB): West Virginia large radio telescope
- Breakthrough Listen (BL): SETI survey using GBT and Parkes Observatory
- GUPPI: radio-telescope back-end aimed at processing pulsar data
- Green Bank Ultimate Pulsar Processing Instrument:
- GUPPI: radio-telescope back-end aimed at processing pulsar data
- green galaxy:
- green pea:
- green pea galaxy:
- green valley:
- green valley galaxy:
- greenhouse effect: mechanism that boosts temperature through selective blocking of EMR
- radiative forcing (RF): difference between a planet's incoming and outgoing radiation
- greenhouse gas:
- earthshine: reflected and emitted electromagnetic radiation from Earth
- greenhouse effect: mechanism that boosts temperature through selective blocking of EMR
- Greenland:
- Greenland Telescope (GLT): 12 m radio telescope in Greenland
- Greenwich mean time:
- time standard: method of designating points in time and quantifying time periods
- Greenwich meridian:
- meridian: circle around the Earth passing through both poles
- time standard: method of designating points in time and quantifying time periods
- Greenwood time constant:
- seeing: apparent blurring and twinkling of objects seen through atmosphere
- Gregorian calendar:
- Gregorian telescope: type of reflector telescope
- Greisen-Zatsepin-Kuzmin effect:
- Greisen-Zatsepin-Kuzmin limit:
- grey body:
- gray body: ideal object that reflects the same fraction of light at any wavelength
- GRG:
- galaxy group: group of fifty or fewer gravitationally bound Milky-Way-sized galaxies
- radio galaxy (RG): a galaxy emitting a lot of radio
- GRID:
- AGILE: Italian space gamma-ray observatory
- Grigg-Skjellerup:
- Giotto: 1980s space mission carrying out a Comet Halley flyby
- grism: combination of a grating and a prism
- GRO:
- GRO J1655-40: microquasar
- Groombridge:
- GROSCE:
- ROTSE: automated array of telescopes to uncover and track transients
- gross structure:
- fine structure: separate spectral lines due to electron spin and relativistic effects
- hyperfine structure: spectral lines from magnetic and spin interactions between electrons and nucleus
- Groth Strip:
- Groth Strip Survey:
- ground:
- Allen Telescope Array (ATA): array of radio telescopes in northern California for SETI
- Anglo-Australian Telescope (AAT): 3.9 m reflector telescope in Australia
- Arecibo Observatory (NAIC): former large 305 m radio telescope in Puerto Rico
- ARGO-YBJ Experiment: cosmic-ray/gamma-ray detector in Tibet
- Atacama B-Mode Search (ABS): 2012-2014 survey of the CMB
- Atacama Cosmology Telescope (ACT): 6 meter microwave survey telescope in Chile
- Atacama Large Millimeter Array (ALMA): large radio telescope array in Chile
- Atacama Pathfinder Experiment (APEX): 12-meter submillimeter telescope in Chile
- Atacama Submillimeter Telescope Experiment (ASTE): ten meter submillimeter telescope in Chile
- AtLAST: concept for submillimeter survey telescope in Chile
- Australia Telescope Compact Array (ATCA): radio telescope in eastern Australia
- Australian Square Kilometre Array Pathfinder (ASKAP): radio telescope array of 36 12-meter dishes
- Automated Planet Finder (APF): robotic telescope to find exoplanets using RV method
- BICEP2: survey to measure the polarization of the CMB
- BIMA telescope: millimeter interferometer in operation 1985 to 2005
- BlackGEM: telescope array in development to follow up gravitational wave signals
- California Extremely Large Telescope (CELT): concept for an extremely large telescope
- Caltech Submillimeter Observatory (CSO,LCT): 10.4 meter submillimeter telescope in Hawaii
- Canada-France-Hawaii Telescope (CFHT): 3.6 meter optical/infrared telescope in Hawaii
- Canadian Hydrogen Intensity Mapping Experiment (CHIME,CH): radio telescope mapping distant neutral hydrogen
- Carbon Monoxide Mapping Array (COMA): planned experiment to observe epoch of reionization
- CCAT: 25-meter submillimeter telescope plan for Chile
- Cerro Tololo Inter-American Observatory (CTIO): NOAO observatory in Chile with Blanco telescope
- CHARA: optical interferometer
- Cherenkov Telescope Array (CTA): ground gamma-ray telescope array in development
- CMB Stage-4 (CMB-S4): planned 2020s-generation of ground CMB observations
- COAST: optical interferometer in England
- Colossus Telescope: concept for a 50-meter telescope using interferometry
- COMAP: high frequency radio telescope to map CO
- Combined Array for Research in Millimeter-wave Astronomy (CARMA): array of radio telescopes in eastern California
- Coronal Solar Magnetism Observatory (COSMO): proposed solar observatory
- Cosmic Anisotropy Telescope (CAT): 1990s interferometer to measure CMB variations
- Cosmic Background Imager (CBI): radio telescope in Chile observing the CMB
- Cosmic Explorer: concept for a very large LIGO-like GW detector
- DSA-2000: array plan to detect radio transients
- Effelsberg 100-m Radio Telescope: German large single-dish radio telescope
- Einstein Telescope: concept for a larger LIGO-like GW detector
- ESO 3.6m Telescope: reflector telescope at La Silla
- European Extremely Large Telescope (E-ELT,ELT): 39-meter telescope under construction
- European Southern Observatory Very Large Telescope (ESO VLT,VLT): four 8.2-meter optical telescopes in Chile that can act together
- Event Horizon Telescope (EHT): growing VLBI network
- FAST: Arecibo-like 500 m telescope in deployment in China
- Fast Fourier Transform Telescope: proposed all-digital telescope with synthetic aperture
- Fenton Hill Observatory (FHO): New Mexico GRB-oriented astronomical observatory
- Fred Lawrence Whipple Observatory (FLWO): observatory near Amado, Arizona
- Fred Young Submillimeter Telescope (FYST,CCAT-p): 6-meter submillimeter survey telescope under construction in Chile
- Gemini Observatory: pair of telescopes in Hawaii and Chile
- GEO600: ground-based gravitational-wave detector in Germany
- Giant Magellan Telescope (GMT): 24.5 meter telescope under construction
- Giant Metrewave Radio Telescope (GMRT): large radio interferometer in India
- Giant Segmented Mirror Telescope (GSMT): concept for an extremely large telescope
- Gran Telescopio Canarias (GTC): 10.4 meter telescope in the Canary Islands
- Green Bank 140 Foot Telescope: West Virginia radio telescope
- Green Bank 300ft Telescope (GB300): former large radio telescope at Green Bank
- Green Bank Telescope (GBT,GB): West Virginia large radio telescope
- Greenland Telescope (GLT): 12 m radio telescope in Greenland
- Hale Telescope: 5.1 m reflector telescope in California
- Haleakala Observatory: observatory on Maui, Hawaii
- HERA: low frequency radio telescope
- High Energy Stereoscopic System (HESS): ground gamma-ray telescope array
- High-altitude Water Cherenkov Observatory (HAWC): gamma ray telescope using Cherenkov radiation
- HIRAX: radio telescope array 21-cm surveying
- Hobby-Eberly Telescope (HET,SST): 10 meter telescope in Texas
- Infrared Survey Facility (IRSF): 140 cm reflector telescope that images in infrared
- Infrared Telescope Maffei (ITM,IRAIT): 80 cm infrared telescope in Antarctica
- IOTA: past optical interferometer in Arizona
- IRAM 30m Telescope: millimeter-range radio telescope in Sierra Nevada, Spain
- IRTF: Mauna Kea 3-meter infrared telescope
- Isaac Newton Telescope (INT): 2.5 m telescope in Canary Islands
- James Clerk Maxwell Telescope (JCMT): far-infrared telescope in Hawaii
- KAGRA: gravitational wave detector in Japan preparing for operation
- Keck Observatory: observatory in Hawaii with two 10-meter reflectors
- Kitt Peak National Observatory (KPNO): NRAO observatory in Arizona with Mayall telescope
- LAMOST: Chinese telescope for spectroscopic surveys of stars and galaxies
- Large Altazimuth Telescope (BTA-6): 6-meter reflector telescope in Russia
- Large Binocular Telescope (LBT): dual 8.4 meter telescope in Arizona
- Large Millimeter Telescope (LMT): large microwave telescope in Mexico
- Large Zenith Telescope (LZT): 6 meter liquid mirror telescope in British Columbia
- Las Cumbres Observatory (LCO): world-wide network of telescopes
- Lick Observatory: California observatory of long standing
- LIGO: pair of observatories to detect gravitational waves
- LIGO-India: planned gravitational wave detector in India
- Livermore Optical Transient Imaging System (LOTIS): automated telescope aiming to catch GRB optical counterparts
- LOPES: cosmic ray detector that detected resulting radio
- Low-frequency Array (LOFAR): low frequency radio telescope
- Lowell Discovery Telescope (LDT,DCT): 4.3 m telescope at Lowell Observatory, Arizona
- Lowell Observatory: Arizona observatory of long standing
- Magellan Telescopes: pair of 6.5 m optical telescopes in Chile
- Mark II (MKII): 38 m radio telescope in England
- Mayall 4m Telescope: 4 meter reflector telescope at Kitt Peak
- MeerKAT: new radio telescope in South Africa
- MeerLICHT: South African telescope coordinated with MeerKAT
- Mercator Telescope: 1.2 m telescope in the Canary Islands
- MERLIN: VLBI array spread across England
- Milagro: gamma ray telescope using Cherenkov radiation
- MMT: 6.5 meter telescope at Mt. Hopkins, Arizona
- Mopra Telescope: Australian 22 m radio telescope
- MRO Interferometer (MROI): optical interferometer in New Mexico
- Murchison Widefield Array (MWA): low frequency radio telescope
- Nançay Radio Telescope (NRT): France large single-dish radio telescope
- NANTEN2: millimeter telescope in Chile
- Navy Precision Optical Interferometer (NPOI): optical interferometer in Arizona
- New Technology Telescope (NTT): 3.58-meter reflector telescope in Chile
- Next Generation Very Large Array (ngVLA): planned radio telescope array as a follow-on to ALMA and the Jansky VLA
- Northern Extended Millimeter Array (NOEMA): large radio telescope array under construction in Europe
- Ooty Radio Telescope (ORT): cylindrical radio telescope in India
- Overwhelmingly Large Telescope (OWL): 100 m telescope plan
- Palomar 48 Inch Telescope (P48): 48 inch Schmidt telescope at Palomar Observatory
- Palomar 60-inch Telescope (P60): 60 inch telescope at Palomar Observatory
- Palomar Observatory: California observatory with Hale telescope
- Palomar Testbed Interferometer (PTI): near-infrared interferometer experiment
- Pan-STARRS: set of survey telescopes
- Parkes Observatory: Australian large single-dish radio telescope
- Plateau de Bure Interferometer (PdBI): 6-dish interferometer in French Alps
- QUaD: survey to measure the polarization of the CMB
- QUBIC: survey to measure the polarization of the CMB
- QUIET: survey to measure the polarization of the CMB
- RATAN-600: ring-shaped radio telescope in Russia
- Rubin Observatory (VRO,LSST): 8-meter survey reflector telescope under construction in Chile
- Sardinia Radio Telescope (SRT): Italian large single-dish radio telescope
- Shane Telescope: 3.05 m reflector telescope at Lick Observatory
- Siding Spring Observatory (SSO): observatory in New South Wales, Australia
- SkyMapper: automated 1.35 m optical telescope in Australia
- Sloan 2.5m Telescope: telescope for SDSS in New Mexico
- SOAR: 4.1 m reflector telescope in Chile
- South African Astronomical Observatory (SAAO): South African observatory with SALT telescope
- South Pole Telescope (SPT): a microwave to radio telescope at South Pole
- Southern African Large Telescope (SALT): 10 meter telescope in South Africa
- Square Kilometre Array (SKA): radio telescope collecting a square kilometer
- Subaru Telescope: 8.2 meter telescope in Hawaii
- Submillimeter Array (SMA): radio interferometer in Hawaii
- Submillimeter Telescope (SMT,HHSMT): 10 meter far-infrared telescope
- Sunyaev-Zel'dovich Array (SZA): array of eight 3.5 meter microwave telescopes
- SUSI: optical interferometer in Australia
- TAMA 300: small prototype gravitational wave detector in Japan
- Telescopio Nazionale Galileo (TNG): 3.58 m telescope in Canary Islands
- Tenerife Experiment: 1980s-1990s survey of CMB anisotropies
- Thirty Meter Telescope (TMT): extremely large telescope planned for Hawaii
- TRAPPIST: ground-based automatic transiting planet finding telescope
- Tunka experiment: Russian Cherenkov detector aimed at cosmic rays and gamma rays
- UK Schmidt Telescope (UKST): 1.2 meter telescope in Australia with wide field-of-view
- United Kingdom Infrared Telescope (UKIRT): Mauna Kea 3.8 meter infrared telescope
- University of Tokyo Atacama Observatory (TAO): observatory for a 6.5 m infrared telescope under construction
- USNO Twin Astrograph: USNO astrograph deployed in 1970
- UTMOST: telescope aiming to detect radio transients
- Víctor M. Blanco Telescope: 4 m reflector telescope in Chile
- VERA: VLBI project to map the Milky Way
- VERITAS: ground gamma ray telescope array in Arizona
- Very Large Array (VLA): radio telescope in New Mexico
- Very Small Array (VSA): radio interferometer in Canary Islands
- Virgo: ground-based gravitational-wave detector in Italy
- VISTA: 4.1 meter telescope in Paranal Observatory in Chile
- VLT Survey Telescope (VST): survey telescope located at the VLT site
- Westerbork Synthesis Radio Telescope (WSRT): radio telescope array of 14 dishes in Netherlands
- William Herschel Telescope (WHT): 4.2 meter telescope in the Canary Islands
- WIYN 3.5m Telescope: Kitt Peak telescope run by university collaboration with NOAO
- Yuan-Tseh Lee Array (YTLA,AMiBA): microwave interferometer in Canary Islands
- ground state: lowest energy level
- Ground-Base Electro-Optical Deep Space Surveillance (GEODSS): initiative to track artificial spacecraft including space junk
- ground-penetrating radar:
- radar: probe based on reflecting radio waves
- group:
- group environment:
- group of galaxies:
- galaxy group: group of fifty or fewer gravitationally bound Milky-Way-sized galaxies
- growth barrier:
- barrier: challenging issue regarding planet formation
- GRS:
- Grus Wall:
- GRW:
- GS:
- gauss (G,Gs): measurement of magnetic field β
- Ginga: 1980s Japanese space X-ray telescope
- GOODS: survey combining data from different sources on very distant objects
- guide star (GS): star used to assist in astronomical observation
- Juno: mission to Jupiter
- GSAOI:
- GSC:
- GSC-I:
- GSC-II:
- GSC2:
- GSFC:
- GSFC xray and EUV Spectroheliograph:
- OSO 7: 1970s observatory-satellite for viewing the Sun
- GSH:
- GSMT:
- GSPC:
- GSPC-I:
- GSPC-II:
- GSS:
- GTC:
- GTCAO+FRIDA:
- GTM:
- GTO:
- Guaranteed Time Observations:
- guest observer (GO): non-affiliated researcher welcomed to use an observatory
- guest observer program:
- guest observer (GO): non-affiliated researcher welcomed to use an observatory
- guest star: translation of ancient Chinese term for a visible transient
- guide star (GS): star used to assist in astronomical observation
- position angle (PA): indication of a direction across the celestial sphere
- Guide Star Catalog (GSC,HSTGC): catalog of stars to help aim HST
- Guide Star Photometric Catalog:
- guide stars:
- position angle (PA): indication of a direction across the celestial sphere
- guillotine factor:
- Gulf of Mexico:
- Chicxulub crater: ancient giant impact crater under Mexico and the Gulf of Mexico
- Gum:
- Gunn-Peterson effect:
- Gunn-Peterson optical depth:
- Gunn-Peterson trough: spectral feature in EMR from redshift 6+
- Guo Shoujing Telescope:
- LAMOST: Chinese telescope for spectroscopic surveys of stars and galaxies
- GUPPI: radio-telescope back-end aimed at processing pulsar data
- GUT:
- electroweak: single conception including both electromagnetic and weak forces
- strong force: force that holds quarks and nuclei together
- symmetry breaking: loss of symmetry, such as due to loss of stability in a regime change
- Theory of Everything (TOE): single law explaining the four forces of nature
- GUVI:
- TIMED: space probe observing Earth upper atmosphere for solar effects
- GW:
- chirp: burst of signal rising or falling in frequency
- extreme mass ratio inspiral (EMRI): inspiraling pair of objects with mass ratio beyond 10,000
- gravitational wave (GW): ripples in the curvature of spacetime propagating as a wave
- GW detection (GW): observed gravitational wave signal recognizable as an astronomical event
- GW background:
- GW detection (GW): observed gravitational wave signal recognizable as an astronomical event
- GW detector:
- GW event:
- GW detection (GW): observed gravitational wave signal recognizable as an astronomical event
- GW memory:
- GW observatory:
- GW spectrum:
- GW strain:
- GW150914:
- gravitational wave (GW): ripples in the curvature of spacetime propagating as a wave
- GW detection (GW): observed gravitational wave signal recognizable as an astronomical event
- LIGO: pair of observatories to detect gravitational waves
- GW151226:
- GW detection (GW): observed gravitational wave signal recognizable as an astronomical event
- GW170104:
- GW detection (GW): observed gravitational wave signal recognizable as an astronomical event
- GW170608:
- GW detection (GW): observed gravitational wave signal recognizable as an astronomical event
- GW170814:
- GW detection (GW): observed gravitational wave signal recognizable as an astronomical event
- GW170817: 2017 gravitational wave detection from a neutron star merger
- GW detection (GW): observed gravitational wave signal recognizable as an astronomical event
- standard siren: transient whose gravitational waves indicate a specific distance
- GWB:
- GX:
- Gy:
- GYL:
- Gyr:
- gyrochronology: means of estimating stellar age from rotation
- GZ2:
- Galaxy Zoo 2 (GZ2): crowd-sourced classification of hundreds of thousands of galaxies
- GZK limit: limit on energy of cosmic rays
Index