Term Index (G)

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Term Index (G)

G:
- G-type star (G): stars similar to the Sun
- gauss (G,Gs): measurement of magnetic field β
- Gini/M20: an automatable method of detecting whether a galaxy has recently merged
- glycine (Gly,G): smallest of the twenty common amino acids
- Lowell Proper Motion Survey (G): 1950s-1970s catalogs of stars with proper motion
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-type star (G): stars similar to the Sun
G numbers:
- Lowell Proper Motion Survey (G): 1950s-1970s catalogs of stars with proper motion
G-class:
- G-type star (G): stars similar to the Sun
G-class star:
- G-type star (G): stars similar to the Sun
G-CLEF: spectrograph on the GMT
- Giant Magellan Telescope (GMT): 24.5 meter telescope under construction
G-dwarf problem: lack of metal-poor G dwarfs in the Milky Way
g-mode:
- asteroseismology: study of stars through analysis of their pulsation
G-type star (G): stars 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:
- James Webb Space Telescope (JWST): future space-based 6.5 meter infrared telescope
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: survey satellite at 400-1000 nanometers
Gaia Data Release 1:
- Gaia: survey satellite at 400-1000 nanometers
Gaia Data Release 2:
- Gaia: survey satellite at 400-1000 nanometers
Gaia DR1:
- Gaia: survey satellite at 400-1000 nanometers
Gaia DR2:
- Gaia: survey satellite at 400-1000 nanometers
Gaia-ESO Survey:
- Gaia: survey satellite at 400-1000 nanometers
gal:
- 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
- Anticenter Shell: nebula at edge of Milky Way
Galactic Archaeology with HERMES:
- GALAH: survey of Milky Way with an emphasis on old structures
galactic binary: system of two object co-orbiting in 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 cirrus:
- infrared cirrus: cirrus-cloud-like infrared emissions from dust, etc.
galactic cluster:
- galaxy cluster (CL): large group of galaxies gravitationally-bound to the group
- open cluster: 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 core:
- galactic center: region at the middle of the Milky Way
galactic corona:
- corona: plasma surrounding a star
- galactic halo: spherical region around a galaxy with gas, dark matter, etc.
galactic electron density: density of electrons in the ISM
galactic equator:
- galactic plane: plane in which the stars of the Milky Way reside
galactic habitable zone:
- habitable zone (HZ): zone where conditions are favorable for life
galactic halo: spherical region around a galaxy with gas, dark matter, etc.
galactic latitude:
- galactic coordinate system (GCS): celestial coordinate system system based upon the galactic plane
galactic longitude:
- galactic coordinate system (GCS): celestial coordinate system system based upon the galactic plane
galactic main sequence:
- galaxy main sequence: relation between galaxies' star formation and stellar mass
galactic north: direction perpendicular to the galactic plane that's north of Earth's equator
galactic north pole:
- galactic north: direction perpendicular to the galactic plane that's north of Earth's equator
galactic nucleus:
- stellar nucleus: group of many stars at the center of a galaxy
galactic period:
- Milky Way: our galaxy
galactic plane: plane in which the stars of the Milky Way reside
- galactic coordinate system (GCS): celestial coordinate system system based upon the galactic plane
Galactic Plane Infrared Polarization Survey:
- Mimir: multi-function near-infrared instrument on Perkins Telescope
galactic planetary nebulae:
- Strasbourg-ESO Catalog of Galactic Planetary Nebulae (PNG): 1992 catalog of 1820 objects
galactic poles:
- galactic plane: plane in which the stars of the Milky Way reside
galactic spheroid:
- galactic halo: spherical region around a galaxy with gas, dark matter, etc.
galactic stellar nucleus:
- stellar nucleus: group of many stars at the center of a galaxy
galactic tide: effect of one galaxy's gravity, such as on another galaxy
galactic year:
- Milky Way: our galaxy
GALAH: survey of Milky Way with an emphasis on old structures
Galatea:
- shepherd moon: small moon at outer edge of a ring
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
- 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
- bulge: denser group of stars within a larger group
- Caldwell Catalog: small catalog for amateur astronomers as an adjunct to the Messier Catalog
- CALIFA: spectroscopic map of 600 galaxies
- 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-magnitude diagram (CMD): diagram relating 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
- dark matter: matter hypothesized to provide galaxies with mass that can't be viewed
- dark matter halo: hypothetical dark matter throughout and surrounding a galaxy
- 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
- dropout: means of identifying distant galaxies
- Dwingeloo Obscured Galaxy Survey (DOGS): radio survey of ZOA for 21cm lines indicating galaxies
- effective radius (R_e): radius of a galaxy within which 1/2 the light is emitted
- escape fraction: fraction of ionizing photons escaping a body
- Extended Chandra Deep Field-South Survey (ECDFS): 1100 square arcminute X-ray survey
- Extended Groth Strip (EGS): region of sky searched for distant galaxies
- Faber-Jackson relation: 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
- Freeman's law: all spiral galaxy's have the same central surface brightness
- fundamental plane: three-way relation between elliptical galaxy characteristics
- 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
- galaxy bias: degree to which galaxy density fails to correspond to dark matter density
- galaxy classification: morphological classification of galaxies
- galaxy cluster (CL): large group of galaxies gravitationally-bound to the group
- 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 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 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: 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
- Kiso Survey of Ultraviolet Excess Galaxies (KUG): 1980 Japanese survey
- KMOS3D: survey of galaxies before to after peak star formation
- LINER: galaxy nucleus emitting spectral lines for ionized and neutral atoms
- luminosity function (LF): function giving number of stars or galaxies at different luminosities
- mass transport: transfer of mass from one part of a body/disk to another
- Messier Catalog (M): catalog of astronomical objects to avoid when looking for comets
- MIGHTEE: radio survey of four established deep fields
- 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
- 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: 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
- planetary nebula luminosity function (PNLF): model used in distance estimation
- Polar-ring Catalog (PRC): 1990 catalog of polar-ring galaxies
- Principal Galaxies Catalog (PGC): modern catalog of more than 70k galaxies
- protogalaxy: gas cloud forming a galaxy
- 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
- Roma-BZCAT: 2013 catalog of blazars
- rotation curve: function of orbital speed to orbital radius for a galaxy
- 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
- 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
- stellar association: like a large open cluster but even less tightly bound
- stellar cluster: group of stars apparently formed by a single cloud
- stellar dynamics: stars' gravitational interaction
- stellar nucleus: group of many stars at the center of a galaxy
- 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
- systemic velocity: average velocity of grouped objects, such as a galaxy
- tidal arm: arm of gas and potentially stars leading from a galaxy
- TiNy Titans (TNT): study of dwarf galaxy pairs
- 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): 1979 catalog of galaxies visible from northern hemisphere
- 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:
- Arakelian Catalog (Ark): 1970s list of small/bright galaxies
GALAXY:
- 3C 273: first quasar discovered
- 3C 295: distant radio galaxy
- 3C 303: Seyfert galaxy
- 3C 327: elliptical radio galaxy
- 3C 48: radio galaxy/quasar
- 3C 9: first quasar discovered
- Andromeda (M31): spiral galaxy in the Local Group
- AzTEC-3: very distant starburst galaxy
- Canis Major Dwarf Galaxy: small irregular galaxy in the Local Group
- Circinus Galaxy (ESO 97-G13): nearest Seyfert galaxy
- Comet Galaxy: spiral galaxy in cluster Abell 2667
- Cygnus A (3C 405,QSO B1957+405): early-discovered radio galaxy and quasar
- ESO 137-001: barred spiral galaxy in the Abell 3627 cluster
- galaxy: gravitationally-bound group of stars
- Haro 29: a blue compact galaxy
- HFLS3: very distant starburst galaxy
- I Zwicky 18 (I Zw 18): blue compact galaxy with low metallicity
- IC 342: spiral galaxy in the Council of Giants
- Large Magellanic Cloud (LMC): irregular satellite galaxy of the Milky Way
- M64: nearby dusty galaxy
- M82: nearby starburst galaxy
- M87: supergiant elliptical galaxy
- Messier 100 (M100,NGC 4321): easily observed spiral galaxy
- Messier 74 (M74,NGC 628): easily observed spiral galaxy
- Messier 84 (M84): elliptical galaxy with jets
- Milky Way: our galaxy
- NGC 1600: elliptical galaxy with supermassive black hole
- NGC 253: spiral galaxy 11 million light-years away
- NGC 2770: spiral galaxy 88 million light-years away
- NGC 3314: a pair of galaxies aligned with us
- NGC 6946: face-on spiral galaxy
- Pinwheel Galaxy (M101): easily-observed spiral galaxy
- Sagittarius Dwarf Elliptical Galaxy (Sgr dE): satellite galaxy of the Milky Way
- Sagittarius Dwarf Irregular Galaxy (SagDIG): most distant galaxy in the Local Group
- SBS 0335-052: blue compact galaxy
- Small Magellanic Cloud (SMC): dwarf galaxy in the Local Group
- Sombrero Galaxy (M104): striking spiral galaxy with very large bulge
- Spindle Galaxy (NGC 5866): striking spiral galaxy with very large bulge
- SuperCOSMOS Sky Survey (SSS): survey of stars and galaxies from legacy plates
- Triangulum Galaxy (M33): small spiral galaxy in the Local Group
- Triangulum II (Tri II): dwarf galaxy in the Local Group
- Ursa Major II Dwarf: dwarf spheroidal galaxy in the Local Group
- Whirlpool Galaxy (M51a,NGC 5194): easily observed spiral galaxy
Galaxy and Mass Assembly Survey:
- GAMA: galaxy spectroscopy survey to roughly 1 Mpc
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 cluster (CL): large group of galaxies gravitationally-bound to the group
- Bullet Cluster: example of two galaxy clusters in collision
- Local Group (LG): group of galaxies including the Milky Way
- Local Volume (LV): region around the Local Group
- Virgo Cluster: nearby large galaxy cluster
galaxy clusters:
- Abell Catalog: galaxy cluster catalog assembled over 1950s-1980s
- Catalog of Galaxies and Clusters of Galaxies (CGCG): list of galaxies/clusters assembled in 1960s
- cluster radius: radius of a galaxy cluster
- dark flow: non-random patterns in peculiar velocity of galaxy clusters
- field galaxy: galaxy not in a cluster or group
- galaxy filament: thread-like formations of galaxies, 50 to 80 megaparsecs
- galaxy group: group of fifty or fewer gravitationally bound Milky-Way-sized galaxies
- intracluster medium (ICM): hot plasma in center of a cluster
- Massive Cluster Survey (MACS): survey of distant clusters evident in ROSAT X-ray data
- Scott effect: bias toward finding clusters that have bright galaxies
- WINGS: all-sky survey investigating known galaxy clusters
galaxy collision:
- galactic tide: effect of one galaxy's gravity, such as on another galaxy
galaxy color magnitude diagram:
- galaxy main sequence: relation between galaxies' star formation and stellar mass
galaxy diagram:
- galaxy main sequence: relation between galaxies' star formation and stellar mass
Galaxy Evolution Explorer (GALEX): observatory-satellite with 50cm ultraviolet telescope
galaxy feedback:
- star formation feedback: mechanisms whereby star formation regulates its own rate
galaxy filament: thread-like formations of galaxies, 50 to 80 megaparsecs
galaxy formation: modeled as collapsing clouds
- epoch of galaxy formation: before z=1, when many galaxies formed
galaxy group: group of fifty or fewer gravitationally bound Milky-Way-sized galaxies
galaxy interaction:
- galactic tide: effect of one galaxy's gravity, such as on another 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 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
galaxy merger mass ratio:
- galaxy merger: combination of galaxies upon collision
galaxy merger timescale:
- galaxy merger: combination of galaxies upon collision
galaxy nucleus:
- active galactic nucleus (AGN): central region of a galaxy with extremely high luminosity
- 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 rotation curve:
- rotation curve: function of orbital speed to orbital radius for a galaxy
galaxy SED: SED of a galaxy, sometimes synthesized from photometric surveys
galaxy sheet:
- galaxy filament: thread-like formations of galaxies, 50 to 80 megaparsecs
galaxy spectral energy distribution:
- galaxy SED: SED of a galaxy, sometimes synthesized from photometric surveys
galaxy supercluster:
- Coma Supercluster: nearby supercluster
- Great Attractor: gravity anomaly at the center of our supercluster
- Hydra-Centaurus Supercluster: near neighbor of Local Supercluster
- Laniakea Supercluster: group of clusters including the Local Group
- Perseus-Pisces Supercluster: nearby supercluster
- Virgo Supercluster: supercluster including the Local Group
galaxy type:
- active galaxy: galaxy with an active, i.e., extremely luminous central region
- Balmer-break galaxy (BBG): a galaxy emitting very little shorter than 3646 angstroms
- brightest cluster galaxy (BCG): a cluster's most luminous galaxy
- disk galaxy: galaxy shaped like a flat circle
- dwarf galaxy: small galaxy with a few billion stars
- dwarf spheroidal galaxy (dSph): spheroidally-shaped dwarf galaxy lacking star formation
- elliptical galaxy: ellipsoidal-shaped galaxy
- emission line galaxy (ELG): a galaxy type characterized by emission lines
- field galaxy: galaxy not in a cluster or group
- first galaxies: targeted highest red-shift galaxies showing little or no metal
- grand design spiral galaxy: spiral galaxy with two just two arms that are well-defined
- hot DOG: high-energy galaxy with a lot of dust
- hypergalaxy: sizeable spiral galaxy with satellites
- hyperluminous infrared galaxy (HLIRG, HyLIRG): a galaxy emitting a more far infrared than an ULIRG
- irregular galaxy: galaxy that's not a disk or ellipsoid
- low-surface-brightness galaxy (LSB galaxy): galaxies less bright than those historically identified
- luminous infrared galaxy (LIRG): a galaxy emitting a lot of far-infrared light
- luminous red galaxy (LRG): distant bright red galaxies in the Sloan Digital Sky Survey
- Lyman-alpha emitter (LAE): redshifted galaxy emitting the Lyman alpha line
- Lyman-break galaxy (LBG): a galaxy emitting very little shorter than 912 angstroms
- Markarian galaxy (Mkn): list of galaxies with excess ultraviolet light
- N galaxy: galaxy with bright nucleus and faint surroundings
- polar-ring galaxy: galaxy encircled by a ring of stars
- quenched galaxy: galaxy currently producing minimal stars
- radio galaxy (RG): a galaxy emitting a lot of radio
- ring galaxy: ring-like galaxy, darker in the middle
- satellite galaxy: galaxy that orbits a larger galaxy
- Seyfert galaxy: visible active galaxy
- spiral galaxy: flat galaxy with spiraling arms
- starburst galaxy: galaxy forming stars at a very high rate
- submillimeter galaxy (SMG): galaxy that produces significant submillimeter radiation
- ultra-faint dwarf galaxy (UFD): recently discovered faint dwarf galaxies in the Local Group
- ultraluminous infrared galaxy (ULIRG): a galaxy emitting a more far infrared than an LIRG
- Wolf-Rayet galaxy: galaxy with a lot of Wolf-Rayet stars
- XBONG: galaxy bright with X-rays but with no evident AGN
galaxy wall:
- galaxy filament: thread-like formations of galaxies, 50 to 80 megaparsecs
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:
- Mars Science Laboratory (MSL): mission to Mars with rover
Galerkin method:
- discontinuous Galerkin method: computational method for PDEs handling discontinuities
GALEX:
- Galaxy Evolution Explorer (GALEX): observatory-satellite with 50cm ultraviolet telescope
GALEX Arecibo SDSS Survey (GASS): HI survey of many galaxies
GALFA-HI:
- Galactic All-sky Survey (GASS): HI survey of the Milky Way
Galilean frame of reference:
- inertial reference frame: frame of reference where no force means no acceleration
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:
- Lorentz transformation: equations describing the effect of relative motion on length and velocity
GALILEO:
- Gal: gravimetry unit of the effect of a planet's gravity
- Galileo: circa 1990s space mission to Jupiter
- Parkes Observatory: Australian large single-dish radio telescope
Galileo Observatory: infrared observatory-plane in the early 1970s
GalMC:
- spectral energy distribution (SED): function or plot of brightness at each wavelength in the spectrum
GAMA: galaxy spectroscopy survey to roughly 1 Mpc
Gamma Leporis A:
- F-type star (F): type of star with about 1.5 times the mass of the Sun
gamma rays: electromagnetic radiation, wavelength 10 picometers and less
- AGILE: Italian space gamma-ray observatory
- Cherenkov Telescope Array (CTA): ground gamma-ray telescope array in development
- Compton Gamma Ray Observatory (CGRO): 1990s space observatory for gamma ray observation
- cosmic gamma ray background (CGB): gamma-ray radiation seen everywhere
- Fermi (FGST,GLAST): satellite for studying gamma rays
- gamma-ray burst (GRB): short flashes of gamma rays apparently from outside our galaxy
- GRANAT: observatory-satellite for detecting gamma rays and X-rays
- GW170817: gravitational wave detection from a neutron star merger
- HEASARC: archive of NASA data on high energy astronomy
- High Energy Stereoscopic System (HESS): ground gamma-ray telescope array
- High-altitude Water Cherenkov Observatory (HAWC): gamma ray telescope using Cherenkov radiation
- INTEGRAL: European gamma ray observatory-satellite
- LOPES: cosmic ray detector that detected resulting radio
- Milagro: gamma ray telescope using Cherenkov radiation
- Solar Maximum Mission (SMM): 1980s satellite to study the Sun during solar maximum
- Swift: satellite for studying gamma-ray bursts
- ultra-high-energy gamma rays (UHEGR): energetic gamma rays with more than 100 TeV photon energy
- very-high-energy gamma rays (VHEGR): energetic gamma rays with 100 GeV to 100 TeV photon energy
gamma-ray burst (GRB): short flashes of gamma rays apparently from outside our galaxy
Gamma-ray Large Area Space Telescope:
- Fermi (FGST,GLAST): satellite for studying gamma rays
Gamow factor:
- Gamow peak: relative speed most likely to cause atoms to fuse
Gamow peak: relative speed most likely to cause atoms to fuse
Ganymede: well-known Jupiter moon
gas:
- atmosphere: gas surrounding astronomical object
- atmospheric escape: escape of gas particles from a planet's atmosphere
- Bok globule: dense molecular cloud
- circumgalactic medium (CGM): gas surrounding a galaxy
- cooling function: function relating a gas's cooling rate to its temperature
- dense core: dense molecular cloud
- 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 planet: planet made largely of gas
- gas streamer: stream of gas
- HI region (HI): cloud of neutral atomic hydrogen
- HI supershell: bubbles of HI hundreds of light-years across
- HII region (HII): cloud of partially-ionized atomic hydrogen
- hydrodynamic escape: ongoing escape of gas particles from atmosphere
- infrared dark cloud (IRDC): molecular cloud not emitting nor transmitting infrared
- intergalactic medium (IGM): matter between galaxies
- interplanetary medium (IPM): matter in the solar system around and between planets
- interstellar medium (ISM): matter within a galaxy between star systems
- Jeans escape: ongoing escape of gas particles from atmosphere
- Jeans parameter (λ): ratio measuring a tendency of an atmosphere to escape
- mass loading: moving gas gaining mass from clouds or stars
- molecular cloud: interstellar gas cloud including molecules
- molecular cloud turbulence: observed turbulence in molecular clouds
- photodissociation region (PDR): cloud of partially-ionized atomic hydrogen
- planetary nebula (PN, PNe): gas shell ejected by a red giant
- protogalaxy: gas cloud forming a galaxy
- protoplanetary nebula (PPN): AGB phase before planetary nebula
- sound speed: speed at which compression waves traverse a gas
- star-forming region (SFR): areas forming stars or ripe for star formation
- surface reaction: such as reactions between gas and adjacent liquid
- thermodynamics: physics of heat and energy
gas blowout:
- quenched galaxy: galaxy currently producing minimal stars
- starburst galaxy: galaxy forming stars at a very high rate
gas constant:
- Boltzmann constant (k,k_B): relates particle energy and temperature
gas disk migration:
- planetary migration: change in planet's orbit
gas dwarf:
- gas planet: planet made largely of gas
- super-Earth: exoplanet more massive than Earth but substantially less than Neptune
gas excitation:
- atomic excitation: atoms with electrons above the ground state
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
- acetylene (C₂H₂): compound of two carbon and two hydrogen atoms
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 torus:
- Io: well-known Jupiter moon
gaseous envelope:
- atmosphere: gas surrounding astronomical object
Gasoline:
- N-body simulation: simulation of many objects gravitationally-bound to each other
GASS:
- Galactic All-sky Survey (GASS): HI survey of the Milky Way
- GALEX Arecibo SDSS Survey (GASS): HI survey of many galaxies
gauge boson:
- standard model: model of elementary particles including quarks
Gaunt factor:
- Kramers opacity law: opacity's relation to density and temperature
gauss (G,Gs): measurement of magnetic field β
Gauss's law:
- Coulomb's law: static electrical force relation
- Maxwell's equations: four equations describing electricity and magnetism
Gaussian distribution:
- Gaussian function: function producing the bell curve
- photon noise: variation in light measurement due to its quantum nature
Gaussian function: function producing the bell curve
GB300:
- 87GB Catalog of Radio Sources (87GB): 1980s Green Bank radio survey
- Becker, White, and Edwards Catalog (BWE): 1990s radio catalog from a 91m Green Bank Telescope survey
- 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
- NRAO Catalog (NRAO): 1960s followup to Cambridge radio surveys
- RASS/Green Bank Catalog (RGB,RASSGB): combined list of radio galaxies from Rosat and Green Bank surveys
GB6:
- Green Bank 6-cm Radio Source Catalog (GB6): catalog of from 1980s northern-hemisphere radio survey
GBM:
- Fermi (FGST,GLAST): satellite for studying gamma rays
GBT:
- DeGaS-MC: GBT survey of potential star formation regions in the Magellanic Clouds
- Green Bank Telescope (GBT): West Virginia large radio telescope
- GUPPI: radio-telescope back-end aimed at processing pulsar data
GC:
- globular cluster (GC): spherical group of stars orbiting a galaxy
- New General Catalogue (NGC): 1888 catalog of galaxies, star clusters, and other nebulae
GC/MS:
- Cassini: explorer spaceship sent to Saturn
GCLF:
- globular cluster luminosity function (GCLF): distribution of brightness of globular clusters
GCM:
- general circulation model (GCM): climate model of a planet's atmosphere or ocean
GCS:
- galactic coordinate system (GCS): celestial coordinate system system based upon the galactic plane
- UKIDSS: five-part infrared survey using UKIRT
GCVS:
- General Catalogue of Variable Stars (GCVS): 20th/21st century catalog of 58000 variable stars
GDSCC:
- NASA Deep Space Network (NASA DSN,DSN): NASA's world-wide radio communication setup
Gemini North:
- Gemini Observatory: pair of telescopes in Hawaii and Chile
- Mauna Kea: Hawaiian mountain, the site of observatories
- Mauna Kea Observatories (MKO): observatories on Mauna Kea in Hawaii
Gemini Observatory: pair of telescopes in Hawaii and Chile
Gemini Planet Imager (GPI): infrared instrument to overcome signal noise imaging exoplanets
- 51 Eridani b: Jupiter-like planet discovered in 2015
Gemini South:
- Gemini Observatory: pair of telescopes in Hawaii and Chile
- Gemini Planet Imager (GPI): infrared instrument to overcome signal noise imaging exoplanets
General Automatic Luminosity And X-Y:
- SuperCOSMOS Sky Survey (SSS): survey of stars and galaxies from legacy plates
General Catalogue of Double Stars Within 121° of the North Pole:
- Burnham Double Star Catalogue (BDS,BU): 1906 catalog with multiple star systems and non-orbiting double stars
General Catalogue of Nebulae and Clusters of Stars:
- New General Catalogue (NGC): 1888 catalog of galaxies, star clusters, and other nebulae
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 relativity (GR): formula relating gravity, space, time, and mass
geocentric gravitational constant:
- standard gravitational parameter (μ): a body's mass times the gravitational constant
geocentric system:
- heliocentric system: model of the universe with the planets orbiting the Sun
geochemistry: the chemistry of the Earth, planets, and moons
geodesic: equivalent to a straight line in curved space
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
- 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 from earthquakes
- silicate: type of compound including silicon and oxygen
- stratigraphy: study of rock layering
- tide: affect 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:
- diffraction: effect of an obstacle on a wave
geometry:
- axisymmetric: identical in any direction from an axis
- conic section: orbit shapes, like the intersection of a plane and cone
- curvature: unflatness of space
- general relativity (GR): formula relating gravity, space, time, and mass
- geodesic: equivalent to a straight line in curved space
- torus coordinates: coordinates for toruses
geopotential model:
- Goddard gravity model (GGM): gravity model produced by Goddard Space Flight Center
- J₂: geopotential coefficient regarding a planet's oblateness
geosignature: geological sign of consequences of life
geostationary:
- orbital speed: speed of an orbiting body around the barycenter of a system
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
German:
- eROSITA: future space X-ray telescope
- ROSAT: 1990s German space X-ray telescope
German Aerospace Center:
- SOFIA: aircraft-based infrared observatory
germanium:
- r-process: synthesization of elements through neutron capture faster than beta decay
Germany:
- Effelsberg 100-m Radio Telescope: German large single-dish radio telescope
- Institute of Theoretical Astrophysics (ITA): Heidelberg research institute
- LOPES: cosmic ray detector that detected resulting radio
- Max Planck Institute for Astronomy (MPIA): Heidelberg research institute
- Max Planck Institute for Radio Astronomy (MPIR): Bonn research institute
GES:
- Gaia: survey satellite at 400-1000 nanometers
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
GHRS:
- HRS: high resolution spectrography
- Hubble Space Telescope (HST): observatory-satellite with 2.4 meter reflective telescope
GI:
- gravitational instability (GI): instability due to gravity
GI dynamo:
- dynamo: mechanism for generating magnetic fields around astronomical bodies
GI2T: optical interferometer in France
- optical interferometer: interferometer of visible light
GIADA:
- Rosetta: space probe that visited a comet
GIANO:
- Telescopio Nazionale Galileo (TNG): 3.58m telescope in Canary Islands
giant impact:
- impact: collision of one solid body with another
giant impact theory:
- impact: collision of one solid body with another
giant impacts:
- planet formation: process by which planets form
Giant Magellan Telescope (GMT): 24.5 meter telescope under construction
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 planets:
- helium rain: possible source of heat in giant planet atmospheres
giant radio galaxy:
- radio galaxy (RG): a galaxy emitting a lot of radio
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
giant-impact hypothesis:
- moon: a planet's natural satellite, such as Earth's
- Moon formation: process by which the Moon and other moons formed
Giclas:
- Lowell Proper Motion Survey (G): 1950s-1970s catalogs of stars with proper motion
gigayear (Gy,Gyr): a billion years
GIMIC:
- EAGLE: simulation of galaxy formation and evolution
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
GISMO: 2 mm bolometer camera on IRAM 30m telescope
GISS GCM ModelE:
- ROCKE-3D: Rocky-planet-oriented general circulation model
GIZMO:
- N-body simulation: simulation of many objects gravitationally-bound to each other
GJ:
- Gliese-Jahreiss Catalog (GJ): 1991 catalog of stars within 25 parsecs
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
GK dwarf:
- Kepler Telescope: space telescope that watched stars for exoplanets
Gl:
- Gliese Catalogue of Nearby Stars (Gl,Gliese): 1950s catalog of stars within 20 parsecs
GLAS:
- William Herschel Telescope (WHT): 4.2 meter telescope in the Canary Islands
GLAST:
- Fermi (FGST,GLAST): satellite for studying gamma rays
Gliese:
- Gliese Catalogue of Nearby Stars (Gl,Gliese): 1950s catalog of stars within 20 parsecs
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:
- Kapteyn's Star: nearby M dwarf
Gliese 388:
- AD Leonis (AD Leo): active red dwarf
Gliese 411:
- Lalande 21185: nearby red dwarf
Gliese 436 b:
- comet planet: planet with some characteristics of a comet
Gliese 581:
- M-type star (M): type of star with a temperature in the vicinity of 2500K
Gliese 65:
- Luyten 726-8: nearby binary star system
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
- Gliese Catalogue of Nearby Stars (Gl,Gliese): 1950s catalog of stars within 20 parsecs
GLIMPSE:
- Spitzer Space Telescope (SST): a satellite with infrared telescope
global astrometry:
- astrometry: precise measurement of the position and movement of stars
global climate model:
- general circulation model (GCM): climate model of a planet's atmosphere or ocean
Global Microlensing Alert Network:
- GMAN: collaboration to alert on microlensing transients
globular cluster (GC): spherical group of stars orbiting a galaxy
- 47 Tucanae (47 Tuc): bright globular cluster
- Messier 15 (M15): globular cluster with collapsed core
- NGC 1866: globular cluster of interest in the LMC
- NGC 3201: globular cluster in which a black hole has been identified
- Omega Centauri: large globular cluster
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 clusters:
- globular cluster luminosity function (GCLF): distribution of brightness of globular clusters
- HBK: study of M31 globular clusters
- M87: supergiant elliptical galaxy
- SKHB: survey of globular clusters in M31
GLT:
- Greenland Telescope (GLT): 12m radio telescope in Greenland
Glue: visualization software good for astrophysical data
gluino:
- supersymmetry: extension to standard model of particle physics
gluon:
- particle: very small thing
- standard model: model of elementary particles including quarks
- supersymmetry: 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
GMACS:
- Giant Magellan Telescope (GMT): 24.5 meter telescope under construction
GMAN: collaboration to alert on microlensing transients
GMC:
- giant molecular cloud (GMC): interstellar gas cloud with molecules, thousands of solar masses
GMM:
- Goddard gravity model (GGM): gravity model produced by Goddard Space Flight Center
GMOS:
- Gemini Observatory: pair of telescopes in Hawaii and Chile
GMRT:
- Giant Metrewave Radio Telescope (GMRT): large radio interferometer in India
GMT:
- Atacama Desert: high altitude, dry plateau in Chile, the site of observatories
- extremely large telescope (ELT): optical telescope with a 20+ meter aperture
- Giant Magellan Telescope (GMT): 24.5 meter telescope under construction
- time standard: method of designating points in time and quantifying time periods
GMT - CfA Large Earth Finder:
- G-CLEF: spectrograph on the GMT
GMT-consortium Large Earth Finder:
- G-CLEF: spectrograph on the GMT
GMTIFS:
- Giant Magellan Telescope (GMT): 24.5 meter telescope under construction
GMTNIRS:
- Giant Magellan Telescope (GMT): 24.5 meter telescope under construction
GN:
- Atlas of Galactic Nebulae (GN): 1980s catalog of Milky-Way nebulae
- GOODS: survey combining data from different sources on very distant objects
GNS:
- GOODS NICMOS Survey (GNS): survey with HST NICMOS instrument of galaxies in GOODS fields
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:
- Gould's Belt Distances Survey (GOBELINS): survey of parallax distances to Gould's Belt YSOs
Goddard Earth Gravity Model:
- Goddard gravity model (GGM): gravity model produced by Goddard Space Flight Center
Goddard gravitational model:
- Goddard gravity model (GGM): gravity model produced by Goddard Space Flight Center
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 30m telescope
Goddard Lunar Gravity Model:
- Goddard gravity model (GGM): gravity model produced by Goddard Space Flight Center
Goddard Mars Gravity Model:
- Goddard gravity model (GGM): gravity model produced by Goddard Space Flight Center
Goddard Mars Model:
- Goddard gravity model (GGM): gravity model produced by Goddard Space Flight Center
Goddard Space Flight Center (GSFC): NASA space research laboratory near Washington D.C.
Godunov scheme: computational fluid dynamics method
Godunov's scheme:
- Godunov scheme: computational fluid dynamics method
Goldilocks zone:
- habitable zone (HZ): zone where conditions are favorable for life
Goldstone Deep Space Communications Complex:
- NASA Deep Space Network (NASA DSN,DSN): NASA's world-wide radio communication setup
GOLF:
- Solar and Heliospheric Observatory (SOHO): satellite observing the Sun
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
Gould Belt:
- Gould's Belt: ring of stars around the sky
Gould designation:
- Flamsteed designation: star designation system dating from 1700s
Gould's Belt: ring of stars around the sky
Gould's Belt Distances Survey (GOBELINS): survey of parallax distances to Gould's Belt YSOs
Gpc:
- Pan-STARRS: set of survey telescopes
- parsec (pc): about 3.26 light-years
GPI:
- 51 Eridani b: Jupiter-like planet discovered in 2015
- Gemini Observatory: pair of telescopes in Hawaii and Chile
- Gemini Planet Imager (GPI): infrared instrument to overcome signal noise imaging exoplanets
GPIPS:
- Mimir: multi-function near-infrared instrument on Perkins Telescope
GPR:
- radar: probe based on reflecting radio waves
GPS:
- time dilation: relativity's ability to make time longer
- UKIDSS: five-part infrared survey using UKIRT
GR:
- general relativity (GR): formula relating gravity, space, time, and mass
GR1D: core collapse supernova simulation in 1D with GR
gradient:
- mathematical field: function of three variables, potentially representing space
grain:
- cosmic dust: cosmic dust is dust in space such as interstellar dust
grams per mole:
- mean molecular weight (μ): measurement of a gas usual for approximating in gas models
Gran Telescopio Canarias (GTC): 10.4 meter telescope in the Canary Islands
Gran Telescopio Milimétrico:
- Large Millimeter Telescope (LMT): large microwave telescope in Mexico
GRANAT: observatory-satellite for detecting gamma rays and X-rays
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:
- subsatellite: object orbiting a moon
granulation:
- Sun: star at center of solar system
granule:
- facula: bright spot on a planet or the Sun
- Sun: star at center of solar system
graph:
- error bar: feature of a graph to indicate accuracy
graph theory:
- dendrogram: diagram of a "tree", i.e., of a graph without cycles
grating: spectrometer component
grating prism:
- grism: combination of a grating and a prism
grating spectrometer:
- grating: spectrometer component
gravimeter:
- gravimetry: measurement of gravity's strength
gravimetry: measurement of gravity's strength
gravitation:
- gravity: theory that mass attracts
gravitational collapse: shrinking of an object from gravitational force
gravitational collapse energy:
- gravitational collapse: shrinking of an object from gravitational force
gravitational constant: indicates how much pull between two masses
gravitational field: gravitational force as distributed over a space
gravitational 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 lensing: focusing electromagnetic radiation by gravitational force
- Bullet Cluster: example of two galaxy clusters in collision
- Deep Lens Survey (DLS): investigating mass distribution of the universe
- gravitational microlensing: gravitational lensing by "small" objects such as individual stars and planets
- NOAO Deep Wide-field Survey (NDWFS): survey investigating large scale structure of the universe
- weak lensing: slight lensing detected in random patterns of distant objects
gravitational locking:
- tidal locking: locked rotation of an orbiting body
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:
- Goddard gravity model (GGM): gravity model produced by Goddard Space Flight Center
gravitational moment:
- J₂: geopotential coefficient regarding a planet's oblateness
gravitational potential (Φ): conceptual field indicating the strength of gravity at each point
gravitational potential energy:
- gravitational potential (Φ): conceptual field indicating the strength of gravity at each point
gravitational primary:
- primary: central body of a system such as the Sun in the solar system
gravitational pumping:
- planet formation: process by which planets form
gravitational quadrupole radiation:
- gravitational wave (GW): ripples in the curvature of spacetime propagating as a wave
gravitational radius:
- Schwarzschild radius: radius of a black hole's event horizon
gravitational redshift: redshift due to GR effects of gravity
gravitational scattering:
- planetary migration: change in planet's orbit
gravitational separation:
- atmosphere: gas surrounding astronomical object
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 dilation:
- time dilation: relativity's ability to make time longer
gravitational wave (GW): ripples in the curvature of spacetime propagating as a wave
gravitational wave astronomy:
- gravitational wave (GW): ripples in the curvature of spacetime propagating as a wave
gravitational wave background (GWB): combination of weak gravitational waves such as from distant sources
- cosmic background radiation (CBR): electromagnetic radiation coming from every direction
- gravitational wave (GW): ripples in the curvature of spacetime propagating as a wave
- Hellings and Downs curve: expected correlation in pulsar timing residuals from random waves
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:
- optical interferometer: interferometer of visible light
gravitational wave event:
- black hole merger: two black holes meeting and forming one
- 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
- neutron star merger: two neutron stars meeting and forming one
gravitational wave spectrum: various frequencies of gravitational waves
gravitational wave strain (h): a measure of the magnitude of a gravitational wave
gravitational waves:
- black hole merger: two black holes meeting and forming one
- Cosmic Explorer: concept for a very large LIGO-like GW detector
- Einstein Telescope: concept for a larger LIGO-like GW detector
- European Gravitational Observatory (EGO): gravitational wave observatory in Italy
- European Pulsar Timing Array (EPTA): European collaboration of radio telescopes
- gravitational wave strain (h): a measure of the magnitude of a gravitational wave
- gravitational-wave memory: a gravitational wave that does not return
- GW170817: gravitational wave detection from a neutron star merger
- Hellings and Downs curve: expected correlation in pulsar timing residuals from random waves
- International Pulsar Timing Array (IPTA): organization of pulsar timing arrays
- KAGRA: pair of interferometers to detect gravitational waves
- LIGO: pair of observatories to detect gravitational waves
- LIGO-India: planned gravitational wave detector in India
- LISA: proposed space mission to detect gravitational waves
- NANOGrav: effort to detect gravitational waves through pulsar timing
- nanohertz gravitational waves: size of GWs that pulsar-timing observations might catch
- neutron star merger: two neutron stars meeting and forming one
- New Gravitational Wave Observatory (NGO): proposed space mission to detect gravitational waves
- Parkes Pulsar Timing Array (PPTA): group of pulsars timed by Parkes Observatory
- pulsar timing array (PTA): cooperating set of pulsar timing observatories
- Sombrero Galaxy (M104): striking spiral galaxy with very large bulge
- Virgo: ground-based gravitational-wave detector in Italy
gravitational-wave memory: a gravitational wave that does not return
gravithermal catastrophe:
- globular cluster (GC): spherical group of stars orbiting a galaxy
gravitometer:
- gravimetry: measurement of gravity's strength
gravitoturbulence:
- gravitational instability model: model for the formation of giant planets
GRAVITY:
- accretion: enlargement of an astronomical body by gravitationally attracting additional mass
- accretion disk: disk around an astronomical body of material that is accreting
- advection dominated accretion flow (ADAF): accretion without radiating much energy
- black hole (BH): region of such high mass that light cannot escape
- black hole binary (BHB,BBH): two black holes co-orbiting
- CMB lensing: gravitational lensing of the CMB
- cosmic string: rent in spacetime
- dark energy: energy theorized to accelerate the expansion of the universe
- dark flow: non-random patterns in peculiar velocity of galaxy clusters
- dark matter: matter hypothesized to provide galaxies with mass that can't be viewed
- dark matter halo: hypothetical dark matter throughout and surrounding a galaxy
- DGP gravity: alternative theory of gravity addressing "dark energy"
- ejection: forcing or throwing something out
- escape velocity (V_e): minimal velocity that allows something to overcome a body's gravity
- European Southern Observatory Very Large Telescope (ESO VLT,VLT): four 8.2-meter optical telescopes in Chile that can act together
- field lines: lines showing the pattern of a mathematical field
- free-fall time: time it would take a body to collapse if unopposed
- Gal: gravimetry unit of the effect of a planet's gravity
- galactic tide: effect of one galaxy's gravity, such as on another galaxy
- Goddard gravity model (GGM): gravity model produced by Goddard Space Flight Center
- gravimetry: measurement of gravity's strength
- gravitational collapse: shrinking of an object from gravitational force
- gravitational constant: indicates how much pull between two masses
- gravitational field: gravitational force as distributed over a space
- gravitational instability (GI): instability due to gravity
- gravitational lensing: focusing electromagnetic radiation by gravitational force
- gravitational microlensing: gravitational lensing by "small" objects such as individual stars and planets
- gravitational potential (Φ): conceptual field indicating the strength of gravity at each point
- gravitational wave (GW): ripples in the curvature of spacetime propagating as a wave
- gravitational wave background (GWB): combination of weak gravitational waves such as from distant sources
- gravitational wave spectrum: various frequencies of gravitational waves
- gravity: theory that mass attracts
- gravity sounding: measuring a planet's gravitation field by study of nearby probe flights
- gravity wave: wave in fluid where restoring force is gravity
- GW detection (GW): observed gravitational wave signal recognizable as an astronomical event
- halo abundance matching (HAM): method of comparing observed galaxies with cosmology models
- internal gravity wave: ripples in a change in density in a fluid
- J₂: geopotential coefficient regarding a planet's oblateness
- Legendre polynomials: useful sequence of polynomials
- modified Newtonian dynamics (MOND): alternative theory of gravity addressing "dark matter"
- multipole expansion: series expansion of a function over the surface of a sphere
- pebble accretion: accretion of pebble-sized solids to a planetary embryo
- Roche limit: nearest a body can orbit another and survive
- standard gravitational parameter (μ): a body's mass times the gravitational constant
- strong force: force that holds quarks and nuclei together
- strong-field gravity: gravity much stronger than in the solar system such as near a black hole
- surface gravity: force felt at the surface of a body
- tidal arm: arm of gas and potentially stars leading from a galaxy
- tidal force: affect of a third body on the gravitational force between two bodies
- tidal heating: heating due to friction from motions caused by tidal force
- tide: affect of Moon's gravity on Earth's seas, etc.
- weak lensing: slight lensing detected in random patterns of distant objects
- wormhole: connection between two regions in a curved space
gravity anomaly:
- gravimetry: measurement of gravity's strength
gravity harmonics:
- J₂: geopotential coefficient regarding a planet's oblateness
gravity model:
- Goddard gravity model (GGM): gravity model produced by Goddard Space Flight Center
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:
- gravimetry: measurement of gravity's strength
gravity wave: wave in fluid where restoring force is gravity
gravity-sensitive spectral lines:
- surface gravity: force felt at the surface of a body
gray atmosphere: a model atmosphere whose opacity does not depend upon wavelength
- equation of radiative transfer (RTE): equation describing energy transfer by EMR
- Rosseland mean opacity: a useful weighted average of opacities at all the wavelengths
- stellar structure: the presumed internal structure of stars
grazing incident optics:
- NuSTAR: space telescope for high-energy X-rays
GRB:
- gamma-ray burst (GRB): short flashes of gamma rays apparently from outside our galaxy
GRB 170817A:
- GW170817: gravitational wave detection from a neutron star merger
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 circle:
- meridian: circle around the Earth passing through both poles
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 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 300ft Telescope (GB300): former large radio telescope at Green Bank
Green Bank 91m Telescope:
- Green Bank 300ft Telescope (GB300): former large radio telescope at Green Bank
Green Bank Observatory:
- 87GB Catalog of Radio Sources (87GB): 1980s Green Bank radio survey
- 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 Telescope (GBT): West Virginia large radio telescope
Green Bank Telescope (GBT): West Virginia large radio telescope
- 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 valley:
- galaxy main sequence: relation between galaxies' star formation and stellar mass
green valley galaxy:
- galaxy main sequence: relation between galaxies' star formation and stellar mass
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): 12m radio telescope in Greenland
Greenland Telescope (GLT): 12m 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
Greenwood time constant:
- seeing: apparent blurring and twinkling of objects seen through atmosphere
Gregorian telescope: type of reflecting telescope
Greisen-Zatsepin-Kuzmin limit:
- GZK limit: limit on energy of cosmic rays
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
grism: combination of a grating and a prism
GRO:
- Compton Gamma Ray Observatory (CGRO): 1990s space observatory for gamma ray observation
GRO J1655-40: microquasar
Groombridge:
- Catalog of Circumpolar Stars (Groombridge): list of over 4000 stars in northern part of the sky
gross structure:
- fine structure: spectral lines due to electron spin and relativistic effects
- hyperfine structure: spectral lines from magnetic and spin interactions between electrons and nucleus
Groth Strip:
- DEEP2: redshift survey of 60,000 galaxies
- Extended Groth Strip (EGS): region of sky searched for distant galaxies
Groth Survey Strip:
- Extended Groth Strip (EGS): region of sky searched for distant galaxies
ground:
- Allen Telescope Array (ATA): array of radio telescopes in northern California for SETI
- Anglo-Australian Telescope (AAT): 3.9m reflector telescope in Australia
- Arecibo Observatory (NAIC): large 305m radio telescope in Puerto Rico
- 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
- Australia Telescope Compact Array (ATCA): radio telescope in eastern Australia
- Australian Square Kilometre Array Pathfinder (ASKAP): radio telescope array of 36 12m dishes
- BlackGEM: telescope array in development to follow up gravitational wave signals
- Canada-France-Hawaii Telescope (CFHT): 3.6 meter optical/infrared telescope in Hawaii
- Canadian Hydrogen Intensity Mapping Experiment (CHIME): 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
- CCAT-prime (CCAT-p): planned 6 meter submillimeter telescope in Chile
- Cerro Tololo Inter-American Observatory (CTIO): observatory near Amado, Arizona
- Cherenkov Telescope Array (CTA): ground gamma-ray telescope array in development
- CMB Stage-4 (CMB-S4): planned 2020s-generation of ground CMB observations
- 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 Explorer: concept for a very large LIGO-like GW detector
- Discovery Channel Telescope (DCT): 4.3m telescope at Lowell Observatory, Arizona
- Effelsberg 100-m Radio Telescope: German large single-dish radio telescope
- Einstein Telescope: concept for a larger LIGO-like GW detector
- 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 500m telescope in deployment in China
- Fast Fourier Transform Telescope: proposed all-digital telescope with synthetic aperture
- Fred Lawrence Whipple Observatory (FLWO): observatory near Amado, Arizona
- Gemini Observatory: pair of telescopes in Hawaii and Chile
- Giant Magellan Telescope (GMT): 24.5 meter telescope under construction
- Giant Metrewave Radio Telescope (GMRT): large radio interferometer in India
- 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): West Virginia large radio telescope
- Greenland Telescope (GLT): 12m radio telescope in Greenland
- Hale Telescope: 5.1m reflector telescope in California
- HERA: low frequency radio telescope
- High-altitude Water Cherenkov Observatory (HAWC): gamma ray telescope using Cherenkov radiation
- HIRAX: radio telescope array 21 cm surveying
- Hobby-Eberly Telescope (HET): 9.2 meter telescope in Texas
- Infrared Survey Facility (IRSF): 140 cm reflector telescope that images in infrared
- IRAM 30m Telescope: millimeter-range radio telescope in Sierra Nevada, Spain
- IRTF: Mauna Kea 3-meter infrared telescope
- James Clerk Maxwell Telescope (JCMT): far-infrared telescope in Hawaii
- KAGRA: pair of interferometers to detect gravitational waves
- Keck Observatory: observatory in Hawaii with two 10-meter reflectors
- 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 Synoptic Survey Telescope (LSST): 8-meter survey reflecting telescope under construction in Chile
- Large Zenith Telescope (LZT): 6 meter liquid mirror telescope in British Columbia
- LIGO: pair of observatories to detect gravitational waves
- LIGO-India: planned gravitational wave detector in India
- LOPES: cosmic ray detector that detected resulting radio
- Low-frequency Array (LOFAR): low frequency radio telescope
- Magellan Telescopes: pair of 6.5m optical telescopes in Chile
- Mark II (MKII): 38m radio telescope in England
- Mayall 4m Telescope: 4m reflector telescope at Kitt Peak
- MeerKAT: new radio telescope in South Africa
- MeerLICHT: South African telescope to coordinate with MeerKAT
- Mercator Telescope: 1.2m telescope in the Canary Islands
- Milagro: gamma ray telescope using Cherenkov radiation
- MMT: 6.5 meter telescope at Mt. Hopkins, Arizona
- Murchison Widefield Array (MWA): low frequency radio telescope
- Nançay Radio Telescope (NRT): France large single-dish radio telescope
- NANTEN2: millimeter telescope in Chile
- New Technology Telescope (NTT): 3.58 meter reflecting 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): 100m 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
- 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
- Sardinia Radio Telescope (SRT): Italian large single-dish radio telescope
- SkyMapper: automated 1.35m optical telescope in Australia
- Sloan 2.5m Telescope: telescope for SDSS in New Mexico
- 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
- Telescopio Nazionale Galileo (TNG): 3.58m telescope in Canary Islands
- Thirty Meter Telescope (TMT): extremely large telescope planned for Hawaii
- TRAPPIST: ground-based automatic transiting planet finding telescope
- 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 6.5m infrared telescope under construction
- Víctor M. Blanco Telescope: 4m reflector telescope in Chile
- VERA: VLBI project to map the Milky Way
- 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
ground state:
- atomic excitation: atoms with electrons above the ground state
- false vacuum: apparent QM vacuum
- state of excitation: energy level of something above the minimum
ground-penetrating radar:
- radar: probe based on reflecting radio waves
group:
- Lie transform: type of infinitesimal transform
group of galaxies:
- galaxy group: group of fifty or fewer gravitationally bound Milky-Way-sized galaxies
GRS:
- GRANAT: observatory-satellite for detecting gamma rays and X-rays
- radio source (RS): something in the sky generating radio signal
Grus Wall:
- galaxy filament: thread-like formations of galaxies, 50 to 80 megaparsecs
GS:
- gauss (G,Gs): measurement of magnetic field β
- GOODS: survey combining data from different sources on very distant objects
- Juno: mission to Jupiter
GSAOI:
- Gemini Observatory: pair of telescopes in Hawaii and Chile
GSC:
- Guide Star Catalog (GSC,HSTGC): catalog of stars to help aim HST
GSC-I:
- Guide Star Catalog (GSC,HSTGC): catalog of stars to help aim HST
GSC-II:
- Guide Star Catalog (GSC,HSTGC): catalog of stars to help aim HST
GSFC:
- Goddard Space Flight Center (GSFC): NASA space research laboratory near Washington D.C.
GSFC xray.page and EUV Spectroheliograph:
- OSO 7: 1970s observatory-satellite for viewing the Sun
GSMT:
- Giant Segmented Mirror Telescope (GSMT): concept for an extremely large telescope
GSS:
- Extended Groth Strip (EGS): region of sky searched for distant galaxies
GTC:
- EMPIRE Survey: survey of gas in M51a to follow up PAWS
- Gran Telescopio Canarias (GTC): 10.4 meter telescope in the Canary Islands
GTCAO-FRIDA:
- Gran Telescopio Canarias (GTC): 10.4 meter telescope in the Canary Islands
GTM:
- Large Millimeter Telescope (LMT): large microwave telescope in Mexico
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
guide star:
- position angle: indication of a direction across the celestial sphere
Guide Star Catalog (GSC,HSTGC): catalog of stars to help aim HST
guide stars:
- position angle: indication of a direction across the celestial sphere
guillotine factor:
- Kramers opacity law: opacity's relation to density and temperature
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
GW:
- 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:
- gravitational wave background (GWB): combination of weak gravitational waves such as from distant sources
GW detection (GW): observed gravitational wave signal recognizable as an astronomical event
GW event:
- GW detection (GW): observed gravitational wave signal recognizable as an astronomical event
GW memory:
- gravitational-wave memory: a gravitational wave that does not return
GW spectrum:
- gravitational wave spectrum: various frequencies of gravitational waves
GW strain:
- gravitational wave strain (h): a measure of the magnitude of a gravitational wave
GW150914:
- chirp: burst of signal rising or falling in frequency
- 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: gravitational wave detection from a neutron star merger
- GW detection (GW): observed gravitational wave signal recognizable as an astronomical event
GWB:
- cosmic background radiation (CBR): electromagnetic radiation coming from every direction
- gravitational wave (GW): ripples in the curvature of spacetime propagating as a wave
- gravitational wave background (GWB): combination of weak gravitational waves such as from distant sources
- Hellings and Downs curve: expected correlation in pulsar timing residuals from random waves
Gy:
- gigayear (Gy,Gyr): a billion years
Gyr:
- gigayear (Gy,Gyr): a billion years
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