g (acceleration due to gravity)
G (gravitational constant)
G star
G1.9+0.3
GABA
gabbro
Gabriel's Horn
Gacrux (Gamma Crucis)
gadolinium
Gagarin, Yuri Alexeyevich (1934-1968)
Gagarin Cosmonaut Training Center
GAIA
Gaia Hypothesis
galactic anticenter
galactic bulge
galactic center
Galactic Club
galactic coordinates
galactic disk
galactic empire
galactic equator
galactic habitable zone
galactic halo
galactic magnetic field
galactic noise
galactic nucleus
galactic plane
galactic rotation
galactic window
galactic year
galactocentric distance
galactose
Galatea
GALAXIES
galaxy
galaxy cannibalism
galaxy classification
galaxy formation
galaxy interaction
galaxy merger
Galaxy, The
Galaxy satellite series
Galen (c.AD 129-c. 216)
galena
GALEX (Galaxy Evolution Explorer)
Galilean satellites
Galilean telescope
Galileo (Galilei, Galileo) (1564-1642)
Galileo (spacecraft)
Galileo Europa Mission (GEM)
Galileo satellite navigation system
gall bladder
Galle, Johann Gottfried (1812-1910)
gallic acid
gallium
gallstone
Galois, Évariste (1811-1832)
Galois theory
Galton, Francis (1822-1911)
Galvani, Luigi (1737-1798)
game
game theory
GAMES AND PUZZLES
gamete
gametophyte
Gamma (Soviet orbiting telescope)
Gamma Cassiopeiae
Gamma Cassiopeiae star
gamma function
gamma globulin
gamma rays
Gamma Velorum
gamma-ray burst
gamma-ray satellites
Gamow, George (1904-1968)
ganglion
Ganswindt, Hermann (1856-1934)
gantry
Ganymede
"garbage theory", of the origin of life
gardening
Gardner, Martin (1914-)
Garneau, Marc (1949-)
Garnet Star (Mu Cephei)
Garnet Star Nebula (IC 1396)
GARP (Global Atmospheric Research Project)
Garriott, Owen K. (1930-)
Garuda
gas
gas chromatography
gas constant
gas generator
gas giant
gas laws
gas-bounded nebula
gaseous nebula
gaseous propellant
gaseous-propellant rocket engine
gasoline
Gaspra (minor planet 951)
gastric juice
gastrin
gastrointestinal tract
gastrulation
Gatewood, George D. (1940-)
Gauer-Henry reflex
gauge boson
gauge theory
gaugino
Gauss, Karl Friedrich (1777-1855)
Gaussian
Gay-Lussac, Joseph Louis (1778-1850)
G-class asteroid
GCOM (Global Change Observing Mission)
gegenschein
Geiger-Müller counter
Geizer
gel
gelatin
Gelfond's theorem
gelled propellant
GEM
"gemination," of Martian canals
Geminga
Gemini (constellation)
Gemini Observatory
Gemini Project
Gemini-Titan II
gene
gene amplification
gene expression
gene mapping
gene therapy
gene transfer
General Catalogue of Variable Stars (GCVS)
general precession
general theory of relativity
generation ship
generator
Genesis (inflatable orbiting module)
Genesis (sample return probe)
genetic algorithm
genetic code
genetic counseling
genetic drift
genetic engineering
genetic map
genetic marker
genetic material
genetic pool
genetic recombination
genetic screening
genetics
GENETICS AND HEREDITY
Geneva Extrasolar Planet Search Program
genome
genome, interstellar transmission of
genotype
genus
GEO
geoboard
geocentric
geocorona
geodesic
geodesy
geodesy satellites
geodetic precession
Geographos (minor planet 1620)
geoid
Geo-IK
GEOLOGY AND PLANETARY SCIENCE
geomagnetic field
geomagnetic storm
geometric mean
geometric sequence
geometry
GEOMETRY
geometry puzzles
GEOS (Geodetic Earth Orbiting Satellite)
Geosat
geospace
geostationary orbit
geosynchronous orbit
geosychronous/geostationary transfer orbit (GTO)
geosyncline
Geotail (satellite)
Gergonne point
germ cells
germ layer
germ line
Germain, Sophie (1776-1831)
German Rocket Society
germanium
germination
gestation
Get Off the Earth puzzle
Get-Away Special
Gettier problem
geyser
g-force
GFO (Geosat Follow-On)
GFZ-1 (GeoForschungsZentrum)
ghost crater
Ghost Head Nebula (NGC 2080)
ghost image
Ghost of Jupiter (NGC 3242)
Giacconi, Riccardo (1931-)
Giacobini-Zinner, Comet (Comet 21P/)
giant branch
Giant Magellan Telescope
giant molecular cloud
giant planet
giant star
Giant's Causeway
Gibbs free energy
Gibson, Edward G. (1936-)
gigahertz (GHz)
Gilbert, William (1544-1603)
Gilbreath's conjecture
gill
Gilruth, Robert R. (1913-2000)
gilsonite
gimbal
Ginga
Giotto (ESA Halley probe)
GIRD (Gruppa Isutcheniya Reaktivnovo Dvisheniya)
glacier
gland
Glaser, Donald Arthur (1926-)
Glashow, Sheldon (1932-)
glass
GLAST (Gamma-ray Large Area Space Telescope)
Glauber, Johann Rudolf (1607-1670)
glaucoma
Glavcosmos
Glenn, John Herschel, Jr. (1921-)
Glenn Research Center
Glennan, T(homas) Keith (1905-1995)
glenoid cavity
glia
glial cell
glide
glide angle
glide path
Gliese 229B
Gliese 581
Gliese 67 (HD 10307, HIP 7918)
Gliese 86
Gliese 876
Gliese Catalogue
glissette
glitch
Global Astrometric Interferometer for Astrophysics (GAIA)
Global Microlensing Alert Network (GMAN)
Global Oscillation Network Group (GONG)
Globalstar
globin
globular cluster
globular proteins
globule
globulin
globus pallidus
GLOMR (Global Low Orbiting Message Relay)
GLONASS (Global Navigation Satellite System)
glossopharyngeal nerve
Gloster E.28/39
glottis
glucagon
glucocorticoid
glucose
glueball
gluino
gluon
Glushko, Valentin Petrovitch (1908-1989)
glutamic acid
glutamine
gluteus maximus
glycerol
glycine
glycogen
glycol
glycolysis
glycoprotein
glycosidic bond
glycosuria
glyoxysome
GMAN
GMS (Geosynchronous Meteorological Satellite)
GMT (Greenwich Mean Time)
gneiss
gnomon magic square
Go
Go, No-go
God
Goddard, Robert Hutchings (1882-1945)
Goddard Institute for Space Studies
Goddard Space Flight Center
Gödel, Kurt (1906-1978)
Gödel universe
Gödel's incompleteness theorem
Godwin, Francis (1562-1633)
GOES (Geostationary Operational Environmental Satellite)
goiter
gold
Gold, Thomas (1920-2004)
Goldbach conjecture
golden ratio (phi)
"Goldilocks"
Goldin, Daniel Saul (1940-)
Goldstone Tracking Facility
Golgi apparatus
Golomb, Solomon W.
golygon
GOMS (Geostationary Operational Meteorological Satellite)
gonad
gonadotrophin-releasing hormone
Gonets
Goodricke, John (1764-1786)
googol
Gordian Knot
Gordon, Richard Francis, Jr. (1929-)
Gore, John Ellard (1845-1910)
gorilla
Gorizont
Gott loop
Goudsmit, Samuel Abraham (1902-1978)
Gould, Benjamin Apthorp (1824-1896)
Gould, Stephen Jay 1941-2002)
Gould Belt
gout
governor
GPS (Global Positioning System)
GRAB
graben
GRACE (Gravity Recovery and Climate Experiment)
graceful graph
gradient
Graham, Ronald L.
Graham, Thomas (1805-1869)
Graham's law of diffusion
Graham's number
grain
Gran Telescopio Canarias (GTC)
Granat
Grand Tour
grand unified theory (GUT)
Grandfather Paradox
granite
granulation
granule
granulocyte
granuloma
graph
graph theory
graphite
grapple
graveyard orbit
gravimetric analysis
gravipause
gravireceptor
gravisphere
Gravitational Biology Facility
gravitational collapse
gravitational constant (G)
gravitational energy
gravitational equilibrium
gravitational field
gravitational instability
gravitational loading
gravitational lens
gravitational life
gravitational lock
gravitational microlensing
GRAVITATIONAL PHYSICS
gravitational slingshot effect
gravitational waves
graviton
gravitropism
gravity
gravity gradient
gravity gradient stabilization
Gravity Probe A
Gravity Probe B
gravity-assist
gray (Gy)
gray matter
grayout
grazing-incidence telescope
Great Annihilator
Great Attractor
great circle
Great Comets
Great Hercules Cluster (M13, NGC 6205)
Great Monad
Great Observatories
Great Red Spot
Great Rift (in Milky Way)
Great Rift Valley
Great Square of Pegasus
Great Wall
greatest common divisor
greatest elongation
greatest lower bound
Green, George (1793-1841)
Green, Nathaniel E.
green algae
Green Bank
Green Bank conference (1961)
Green Bank Telescope
green flash
greenhouse effect
greenhouse gases
Green's theorem
Greg, Percy (1836-1889)
Gregorian calendar
Grelling's paradox
Griffith, George (1857-1906)
Griffith Observatory
Grignard reagent
Grimaldi, Francesco Maria (1618-1663)
Grissom, Virgil (1926-1967)
Groom Lake
Groombridge 34
Groombridge Catalogue
grooved terrain
gross
ground meristem
ground state
ground-level event (GLE)
ground-track
group
growth hormone
growth hormone-releasing hormone
Grudge, Project
Gruithuisen, Franz von Paula (1774-1852)
Grus (constellation)
Grus Quartet (NGC 7552, NGC 7582, NGC 7590, and NGC 7599)
GSLV (Geosynchronous Satellite Launch Vehicle)
g-suit
guanine
Guiana Space Centre
guidance
guidance, inertial
guidance, midcourse
guidance system
Guide Star Catalog (GSC)
guided missile
guided missiles, postwar development
Gulfstream (jet)
Gum Nebula
Gurwin
Gusev Crater
gut
guttation
Guy, Richard Kenneth (1916-)
Guzman Prize
gymnosperm
gynoecium
gypsum
gyrofrequency
gyroscope
Gyulbudagian's Nebula (HH215)