Sentences with phrase «off bursts of gamma rays»

The balls are neutron stars and Piran suggests that one - off bursts of gamma rays, which have mystified astronomers for more than two decades, are released when the two neutron stars of a binary system crash into one another.

The merging black holes that led to the discovery of gravitational waves may have been enveloped inside a gigantic star, which gave off a burst of gamma rays

Not exact matches

Like the flashbulbs of paparazzi, gamma - ray bursts pop off all the time in the universe, about one a day.

For this theory to work, the beams released by black holes would have to have strong, self - generated magnetic fields and the rotation of particles around the fields would then give off powerful bursts of gamma ray radiation.

For decades scientists have struggled to explain the origins of gamma - ray bursts, huge blasts of energy that occur daily in far - off galaxies.

Like the flashbulbs of paparazzi, gamma ray bursts pop off all the time in the universe; about one a day but their origin remains elusive.

Since the early 1970s, scientists had debated the nature of gamma - ray bursts, enigmatic flashes of energetic radiation that pop off hundreds of times a year.

The event's unusual characteristics have led researchers to dust off one of the earliest theories for the origin of gamma - ray bursts: that they come from comets that stray too close to neutron stars.

But astronomers may have pulled off an equally challenging feat: detecting the glimmer of a supernova explosion in the fading afterglow of a titanic gamma ray burst (GRB)-- one of the biggest type of explosions in all the cosmos.

Pinpointing the origins of gamma - ray bursts, determining the workings of innate immunity, and extending the use of differential equations to applications in relativity are achievements paying off in Shaw Prizes for the scientists involved.

And gamma - ray bursts — thought to result from especially powerful supernovas or stellar collisions — are so rare that the researchers calculated that, over a billion years, there's only about a 1 in 3 billion chance of one killing off tardigrades.

Off the coast of west Africa, perched on the highest point of the Canary Islands, a gamma - ray telescope called MAGIC — the name stands for the Major Atmospheric Gamma - ray Imaging Cherenkov telescope — scans the heavens for bursts of high - energy photons from far corners of the univgamma - ray telescope called MAGIC — the name stands for the Major Atmospheric Gamma - ray Imaging Cherenkov telescope — scans the heavens for bursts of high - energy photons from far corners of the univGamma - ray Imaging Cherenkov telescope — scans the heavens for bursts of high - energy photons from far corners of the universe.

g (acceleration due to gravity) G (gravitational constant) G star G1.9 +0.3 gabbro Gabor, Dennis (1900 — 1979) 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 plane galactic rotation galactose Galatea GALAXIES galaxy galaxy cannibalism galaxy classification galaxy formation galaxy interaction galaxy merger Galaxy, The Galaxy satellite series Gale Crater 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 gall bladder Galle, Johann Gottfried (1812 — 1910) gallic acid gallium gallon gallstone Galois, Évariste (1811 — 1832) Galois theory Galton, Francis (1822 — 1911) Galvani, Luigi (1737 — 1798) galvanizing galvanometer 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 gangrene Ganswindt, Hermann (1856 — 1934) Ganymede «garbage theory», of the origin of life Gardner, Martin (1914 — 2010) Garneau, Marc (1949 ---RRB- garnet Garnet Star (Mu Cephei) Garnet Star Nebula (IC 1396) garnierite Garriott, Owen K. (1930 ---RRB- Garuda gas gas chromatography gas constant gas giant gas laws gas - bounded nebula gaseous nebula gaseous propellant gaseous - propellant rocket engine gasoline Gaspra (minor planet 951) Gassendi, Pierre (1592 — 1655) gastric juice gastrin gastrocnemius gastroenteritis gastrointestinal tract gastropod gastrulation Gatewood, George D. (1940 ---RRB- Gauer - Henry reflex gauge boson gauge theory gauss (unit) Gauss, Carl Friedrich (1777 — 1855) Gaussian distribution Gay - Lussac, Joseph Louis (1778 — 1850) GCOM (Global Change Observing Mission) Geber (c. 720 — 815) gegenschein Geiger, Hans Wilhelm (1882 — 1945) Geiger - Müller counter Giessler tube gel gelatin Gelfond's theorem Gell - Mann, Murray (1929 ---RRB- GEM «gemination,» of martian canals Geminga Gemini (constellation) Gemini Observatory Gemini Project Gemini - Titan II gemstone gene gene expression gene mapping gene pool 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 code genetic counseling genetic disorder genetic drift genetic engineering genetic marker genetic material genetic pool genetic recombination genetics GENETICS AND HEREDITY Geneva Extrasolar Planet Search Program genome genome, interstellar transmission of genotype gentian violet genus geoboard geode geodesic geodesy geodesy satellites geodetic precession Geographos (minor planet 1620) geography GEOGRAPHY Geo - IK geologic time geology GEOLOGY AND PLANETARY SCIENCE geomagnetic field geomagnetic storm geometric mean geometric sequence geometry GEOMETRY geometry puzzles geophysics GEOS (Geodetic Earth Orbiting Satellite) Geosat geostationary orbit geosynchronous orbit geosynchronous / geostationary transfer orbit (GTO) geosyncline Geotail (satellite) geotropism germ germ cells Germain, Sophie (1776 — 1831) German Rocket Society germanium germination Gesner, Konrad von (1516 — 1565) gestation Get Off the Earth puzzle 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 ---RRB- Giacobini - Zinner, Comet (Comet 21P /) Giaever, Ivar (1929 ---RRB- giant branch Giant Magellan Telescope giant molecular cloud giant planet giant star Giant's Causeway Giauque, William Francis (1895 — 1982) gibberellins Gibbs, Josiah Willard (1839 — 1903) Gibbs free energy Gibson, Edward G. (1936 ---RRB- Gilbert, William (1544 — 1603) gilbert (unit) Gilbreath's conjecture gilding gill gill (unit) Gilruth, Robert R. (1913 — 2000) gilsonite gimbal Ginga ginkgo Giotto (ESA Halley probe) GIRD (Gruppa Isutcheniya Reaktivnovo Dvisheniya) girder glacial drift glacial groove glacier gland Glaser, Donald Arthur (1926 — 2013) Glashow, Sheldon (1932 ---RRB- glass GLAST (Gamma - ray Large Area Space Telescope) Glauber, Johann Rudolf (1607 — 1670) glaucoma glauconite Glenn, John Herschel, Jr. (1921 ---RRB- Glenn Research Center Glennan, T (homas) Keith (1905 — 1995) glenoid cavity glia glial cell glider Gliese 229B Gliese 581 Gliese 67 (HD 10307, HIP 7918) Gliese 710 (HD 168442, HIP 89825) Gliese 86 Gliese 876 Gliese Catalogue glioma glissette glitch Global Astrometric Interferometer for Astrophysics (GAIA) Global Oscillation Network Group (GONG) Globalstar globe Globigerina 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 glow - worm glucagon glucocorticoid glucose glucoside gluon Glushko, Valentin Petrovitch (1908 — 1989) glutamic acid glutamine gluten gluteus maximus glycerol glycine glycogen glycol glycolysis glycoprotein glycosidic bond glycosuria glyoxysome GMS (Geosynchronous Meteorological Satellite) GMT (Greenwich Mean Time) Gnathostomata gneiss Go Go, No - go goblet cell GOCE (Gravity field and steady - state Ocean Circulation Explorer) God Goddard, Robert Hutchings (1882 — 1945) Goddard Institute for Space Studies Goddard Space Flight Center Gödel, Kurt (1906 — 1978) Gödel universe Godwin, Francis (1562 — 1633) GOES (Geostationary Operational Environmental Satellite) goethite goiter gold Gold, Thomas (1920 — 2004) Goldbach conjecture golden ratio (phi) Goldin, Daniel Saul (1940 ---RRB- gold - leaf electroscope Goldstone Tracking Facility Golgi, Camillo (1844 — 1926) Golgi apparatus Golomb, Solomon W. (1932 — 2016) golygon GOMS (Geostationary Operational Meteorological Satellite) gonad gonadotrophin - releasing hormone gonadotrophins Gondwanaland Gonets goniatite goniometer gonorrhea Goodricke, John (1764 — 1786) googol Gordian Knot Gordon, Richard Francis, Jr. (1929 — 2017) Gore, John Ellard (1845 — 1910) gorge 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) Graaf, Regnier de (1641 — 1673) Graafian follicle GRAB graben GRACE (Gravity Recovery and Climate Experiment) graceful graph gradient Graham, Ronald (1935 ---RRB- Graham, Thomas (1805 — 1869) Graham's law of diffusion Graham's number GRAIL (Gravity Recovery and Interior Laboratory) grain (cereal) grain (unit) gram gram - atom Gramme, Zénobe Théophile (1826 — 1901) gramophone Gram's stain Gran Telescopio Canarias (GTC) Granat Grand Tour grand unified theory (GUT) Grandfather Paradox Granit, Ragnar Arthur (1900 — 1991) granite granulation granule granulocyte graph graph theory graphene graphite GRAPHS AND GRAPH THEORY graptolite grass grassland gravel graveyard orbit gravimeter gravimetric analysis Gravitational Biology Facility gravitational collapse gravitational constant (G) gravitational instability gravitational lens gravitational life gravitational lock gravitational microlensing GRAVITATIONAL PHYSICS gravitational slingshot effect gravitational waves graviton gravity gravity gradient gravity gradient stabilization Gravity Probe A Gravity Probe B gravity - assist gray (Gy) gray goo gray matter 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 greater omentum greatest elongation Green, George (1793 — 1841) Green, Nathaniel E. Green, Thomas Hill (1836 — 1882) 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, François Auguste Victor (1871 — 1935) Grignard reagent grike Grimaldi, Francesco Maria (1618 — 1663) Grissom, Virgil (1926 — 1967) grit gritstone Groom Lake Groombridge 34 Groombridge Catalogue gross ground, electrical ground state ground - track group group theory GROUPS AND GROUP THEORY growing season growth growth hormone growth hormone - releasing hormone growth plate 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 G - type asteroid Guericke, Otto von (1602 — 1686) guanine Guiana Space Centre guidance, inertial Guide Star Catalog (GSC) guided missile guided missiles, postwar development Guillaume, Charles Édouard (1861 — 1938) Gulf Stream (ocean current) Gulfstream (jet plane) Gullstrand, Allvar (1862 — 1930) gum Gum Nebula gun metal gunpowder Gurwin Gusev Crater gut Gutenberg, Johann (c. 1400 — 1468) Guy, Richard Kenneth (1916 ---RRB- guyot Guzman Prize gymnosperm gynecology gynoecium gypsum gyrocompass gyrofrequency gyropilot gyroscope gyrostabilizer Gyulbudagian's Nebula (HGamma 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 plane galactic rotation galactose Galatea GALAXIES galaxy galaxy cannibalism galaxy classification galaxy formation galaxy interaction galaxy merger Galaxy, The Galaxy satellite series Gale Crater 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 gall bladder Galle, Johann Gottfried (1812 — 1910) gallic acid gallium gallon gallstone Galois, Évariste (1811 — 1832) Galois theory Galton, Francis (1822 — 1911) Galvani, Luigi (1737 — 1798) galvanizing galvanometer 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 gangrene Ganswindt, Hermann (1856 — 1934) Ganymede «garbage theory», of the origin of life Gardner, Martin (1914 — 2010) Garneau, Marc (1949 ---RRB- garnet Garnet Star (Mu Cephei) Garnet Star Nebula (IC 1396) garnierite Garriott, Owen K. (1930 ---RRB- Garuda gas gas chromatography gas constant gas giant gas laws gas - bounded nebula gaseous nebula gaseous propellant gaseous - propellant rocket engine gasoline Gaspra (minor planet 951) Gassendi, Pierre (1592 — 1655) gastric juice gastrin gastrocnemius gastroenteritis gastrointestinal tract gastropod gastrulation Gatewood, George D. (1940 ---RRB- Gauer - Henry reflex gauge boson gauge theory gauss (unit) Gauss, Carl Friedrich (1777 — 1855) Gaussian distribution Gay - Lussac, Joseph Louis (1778 — 1850) GCOM (Global Change Observing Mission) Geber (c. 720 — 815) gegenschein Geiger, Hans Wilhelm (1882 — 1945) Geiger - Müller counter Giessler tube gel gelatin Gelfond's theorem Gell - Mann, Murray (1929 ---RRB- GEM «gemination,» of martian canals Geminga Gemini (constellation) Gemini Observatory Gemini Project Gemini - Titan II gemstone gene gene expression gene mapping gene pool 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 code genetic counseling genetic disorder genetic drift genetic engineering genetic marker genetic material genetic pool genetic recombination genetics GENETICS AND HEREDITY Geneva Extrasolar Planet Search Program genome genome, interstellar transmission of genotype gentian violet genus geoboard geode geodesic geodesy geodesy satellites geodetic precession Geographos (minor planet 1620) geography GEOGRAPHY Geo - IK geologic time geology GEOLOGY AND PLANETARY SCIENCE geomagnetic field geomagnetic storm geometric mean geometric sequence geometry GEOMETRY geometry puzzles geophysics GEOS (Geodetic Earth Orbiting Satellite) Geosat geostationary orbit geosynchronous orbit geosynchronous / geostationary transfer orbit (GTO) geosyncline Geotail (satellite) geotropism germ germ cells Germain, Sophie (1776 — 1831) German Rocket Society germanium germination Gesner, Konrad von (1516 — 1565) gestation Get Off the Earth puzzle 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 ---RRB- Giacobini - Zinner, Comet (Comet 21P /) Giaever, Ivar (1929 ---RRB- giant branch Giant Magellan Telescope giant molecular cloud giant planet giant star Giant's Causeway Giauque, William Francis (1895 — 1982) gibberellins Gibbs, Josiah Willard (1839 — 1903) Gibbs free energy Gibson, Edward G. (1936 ---RRB- Gilbert, William (1544 — 1603) gilbert (unit) Gilbreath's conjecture gilding gill gill (unit) Gilruth, Robert R. (1913 — 2000) gilsonite gimbal Ginga ginkgo Giotto (ESA Halley probe) GIRD (Gruppa Isutcheniya Reaktivnovo Dvisheniya) girder glacial drift glacial groove glacier gland Glaser, Donald Arthur (1926 — 2013) Glashow, Sheldon (1932 ---RRB- glass GLAST (Gamma - ray Large Area Space Telescope) Glauber, Johann Rudolf (1607 — 1670) glaucoma glauconite Glenn, John Herschel, Jr. (1921 ---RRB- Glenn Research Center Glennan, T (homas) Keith (1905 — 1995) glenoid cavity glia glial cell glider Gliese 229B Gliese 581 Gliese 67 (HD 10307, HIP 7918) Gliese 710 (HD 168442, HIP 89825) Gliese 86 Gliese 876 Gliese Catalogue glioma glissette glitch Global Astrometric Interferometer for Astrophysics (GAIA) Global Oscillation Network Group (GONG) Globalstar globe Globigerina 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 glow - worm glucagon glucocorticoid glucose glucoside gluon Glushko, Valentin Petrovitch (1908 — 1989) glutamic acid glutamine gluten gluteus maximus glycerol glycine glycogen glycol glycolysis glycoprotein glycosidic bond glycosuria glyoxysome GMS (Geosynchronous Meteorological Satellite) GMT (Greenwich Mean Time) Gnathostomata gneiss Go Go, No - go goblet cell GOCE (Gravity field and steady - state Ocean Circulation Explorer) God Goddard, Robert Hutchings (1882 — 1945) Goddard Institute for Space Studies Goddard Space Flight Center Gödel, Kurt (1906 — 1978) Gödel universe Godwin, Francis (1562 — 1633) GOES (Geostationary Operational Environmental Satellite) goethite goiter gold Gold, Thomas (1920 — 2004) Goldbach conjecture golden ratio (phi) Goldin, Daniel Saul (1940 ---RRB- gold - leaf electroscope Goldstone Tracking Facility Golgi, Camillo (1844 — 1926) Golgi apparatus Golomb, Solomon W. (1932 — 2016) golygon GOMS (Geostationary Operational Meteorological Satellite) gonad gonadotrophin - releasing hormone gonadotrophins Gondwanaland Gonets goniatite goniometer gonorrhea Goodricke, John (1764 — 1786) googol Gordian Knot Gordon, Richard Francis, Jr. (1929 — 2017) Gore, John Ellard (1845 — 1910) gorge 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) Graaf, Regnier de (1641 — 1673) Graafian follicle GRAB graben GRACE (Gravity Recovery and Climate Experiment) graceful graph gradient Graham, Ronald (1935 ---RRB- Graham, Thomas (1805 — 1869) Graham's law of diffusion Graham's number GRAIL (Gravity Recovery and Interior Laboratory) grain (cereal) grain (unit) gram gram - atom Gramme, Zénobe Théophile (1826 — 1901) gramophone Gram's stain Gran Telescopio Canarias (GTC) Granat Grand Tour grand unified theory (GUT) Grandfather Paradox Granit, Ragnar Arthur (1900 — 1991) granite granulation granule granulocyte graph graph theory graphene graphite GRAPHS AND GRAPH THEORY graptolite grass grassland gravel graveyard orbit gravimeter gravimetric analysis Gravitational Biology Facility gravitational collapse gravitational constant (G) gravitational instability gravitational lens gravitational life gravitational lock gravitational microlensing GRAVITATIONAL PHYSICS gravitational slingshot effect gravitational waves graviton gravity gravity gradient gravity gradient stabilization Gravity Probe A Gravity Probe B gravity - assist gray (Gy) gray goo gray matter 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 greater omentum greatest elongation Green, George (1793 — 1841) Green, Nathaniel E. Green, Thomas Hill (1836 — 1882) 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, François Auguste Victor (1871 — 1935) Grignard reagent grike Grimaldi, Francesco Maria (1618 — 1663) Grissom, Virgil (1926 — 1967) grit gritstone Groom Lake Groombridge 34 Groombridge Catalogue gross ground, electrical ground state ground - track group group theory GROUPS AND GROUP THEORY growing season growth growth hormone growth hormone - releasing hormone growth plate 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 G - type asteroid Guericke, Otto von (1602 — 1686) guanine Guiana Space Centre guidance, inertial Guide Star Catalog (GSC) guided missile guided missiles, postwar development Guillaume, Charles Édouard (1861 — 1938) Gulf Stream (ocean current) Gulfstream (jet plane) Gullstrand, Allvar (1862 — 1930) gum Gum Nebula gun metal gunpowder Gurwin Gusev Crater gut Gutenberg, Johann (c. 1400 — 1468) Guy, Richard Kenneth (1916 ---RRB- guyot Guzman Prize gymnosperm gynecology gynoecium gypsum gyrocompass gyrofrequency gyropilot gyroscope gyrostabilizer Gyulbudagian's Nebula (HGamma (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 gangrene Ganswindt, Hermann (1856 — 1934) Ganymede «garbage theory», of the origin of life Gardner, Martin (1914 — 2010) Garneau, Marc (1949 ---RRB- garnet Garnet Star (Mu Cephei) Garnet Star Nebula (IC 1396) garnierite Garriott, Owen K. (1930 ---RRB- Garuda gas gas chromatography gas constant gas giant gas laws gas - bounded nebula gaseous nebula gaseous propellant gaseous - propellant rocket engine gasoline Gaspra (minor planet 951) Gassendi, Pierre (1592 — 1655) gastric juice gastrin gastrocnemius gastroenteritis gastrointestinal tract gastropod gastrulation Gatewood, George D. (1940 ---RRB- Gauer - Henry reflex gauge boson gauge theory gauss (unit) Gauss, Carl Friedrich (1777 — 1855) Gaussian distribution Gay - Lussac, Joseph Louis (1778 — 1850) GCOM (Global Change Observing Mission) Geber (c. 720 — 815) gegenschein Geiger, Hans Wilhelm (1882 — 1945) Geiger - Müller counter Giessler tube gel gelatin Gelfond's theorem Gell - Mann, Murray (1929 ---RRB- GEM «gemination,» of martian canals Geminga Gemini (constellation) Gemini Observatory Gemini Project Gemini - Titan II gemstone gene gene expression gene mapping gene pool 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 code genetic counseling genetic disorder genetic drift genetic engineering genetic marker genetic material genetic pool genetic recombination genetics GENETICS AND HEREDITY Geneva Extrasolar Planet Search Program genome genome, interstellar transmission of genotype gentian violet genus geoboard geode geodesic geodesy geodesy satellites geodetic precession Geographos (minor planet 1620) geography GEOGRAPHY Geo - IK geologic time geology GEOLOGY AND PLANETARY SCIENCE geomagnetic field geomagnetic storm geometric mean geometric sequence geometry GEOMETRY geometry puzzles geophysics GEOS (Geodetic Earth Orbiting Satellite) Geosat geostationary orbit geosynchronous orbit geosynchronous / geostationary transfer orbit (GTO) geosyncline Geotail (satellite) geotropism germ germ cells Germain, Sophie (1776 — 1831) German Rocket Society germanium germination Gesner, Konrad von (1516 — 1565) gestation Get Off the Earth puzzle 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 ---RRB- Giacobini - Zinner, Comet (Comet 21P /) Giaever, Ivar (1929 ---RRB- giant branch Giant Magellan Telescope giant molecular cloud giant planet giant star Giant's Causeway Giauque, William Francis (1895 — 1982) gibberellins Gibbs, Josiah Willard (1839 — 1903) Gibbs free energy Gibson, Edward G. (1936 ---RRB- Gilbert, William (1544 — 1603) gilbert (unit) Gilbreath's conjecture gilding gill gill (unit) Gilruth, Robert R. (1913 — 2000) gilsonite gimbal Ginga ginkgo Giotto (ESA Halley probe) GIRD (Gruppa Isutcheniya Reaktivnovo Dvisheniya) girder glacial drift glacial groove glacier gland Glaser, Donald Arthur (1926 — 2013) Glashow, Sheldon (1932 ---RRB- glass GLAST (Gamma - ray Large Area Space Telescope) Glauber, Johann Rudolf (1607 — 1670) glaucoma glauconite Glenn, John Herschel, Jr. (1921 ---RRB- Glenn Research Center Glennan, T (homas) Keith (1905 — 1995) glenoid cavity glia glial cell glider Gliese 229B Gliese 581 Gliese 67 (HD 10307, HIP 7918) Gliese 710 (HD 168442, HIP 89825) Gliese 86 Gliese 876 Gliese Catalogue glioma glissette glitch Global Astrometric Interferometer for Astrophysics (GAIA) Global Oscillation Network Group (GONG) Globalstar globe Globigerina 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 glow - worm glucagon glucocorticoid glucose glucoside gluon Glushko, Valentin Petrovitch (1908 — 1989) glutamic acid glutamine gluten gluteus maximus glycerol glycine glycogen glycol glycolysis glycoprotein glycosidic bond glycosuria glyoxysome GMS (Geosynchronous Meteorological Satellite) GMT (Greenwich Mean Time) Gnathostomata gneiss Go Go, No - go goblet cell GOCE (Gravity field and steady - state Ocean Circulation Explorer) God Goddard, Robert Hutchings (1882 — 1945) Goddard Institute for Space Studies Goddard Space Flight Center Gödel, Kurt (1906 — 1978) Gödel universe Godwin, Francis (1562 — 1633) GOES (Geostationary Operational Environmental Satellite) goethite goiter gold Gold, Thomas (1920 — 2004) Goldbach conjecture golden ratio (phi) Goldin, Daniel Saul (1940 ---RRB- gold - leaf electroscope Goldstone Tracking Facility Golgi, Camillo (1844 — 1926) Golgi apparatus Golomb, Solomon W. (1932 — 2016) golygon GOMS (Geostationary Operational Meteorological Satellite) gonad gonadotrophin - releasing hormone gonadotrophins Gondwanaland Gonets goniatite goniometer gonorrhea Goodricke, John (1764 — 1786) googol Gordian Knot Gordon, Richard Francis, Jr. (1929 — 2017) Gore, John Ellard (1845 — 1910) gorge 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) Graaf, Regnier de (1641 — 1673) Graafian follicle GRAB graben GRACE (Gravity Recovery and Climate Experiment) graceful graph gradient Graham, Ronald (1935 ---RRB- Graham, Thomas (1805 — 1869) Graham's law of diffusion Graham's number GRAIL (Gravity Recovery and Interior Laboratory) grain (cereal) grain (unit) gram gram - atom Gramme, Zénobe Théophile (1826 — 1901) gramophone Gram's stain Gran Telescopio Canarias (GTC) Granat Grand Tour grand unified theory (GUT) Grandfather Paradox Granit, Ragnar Arthur (1900 — 1991) granite granulation granule granulocyte graph graph theory graphene graphite GRAPHS AND GRAPH THEORY graptolite grass grassland gravel graveyard orbit gravimeter gravimetric analysis Gravitational Biology Facility gravitational collapse gravitational constant (G) gravitational instability gravitational lens gravitational life gravitational lock gravitational microlensing GRAVITATIONAL PHYSICS gravitational slingshot effect gravitational waves graviton gravity gravity gradient gravity gradient stabilization Gravity Probe A Gravity Probe B gravity - assist gray (Gy) gray goo gray matter 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 greater omentum greatest elongation Green, George (1793 — 1841) Green, Nathaniel E. Green, Thomas Hill (1836 — 1882) 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, François Auguste Victor (1871 — 1935) Grignard reagent grike Grimaldi, Francesco Maria (1618 — 1663) Grissom, Virgil (1926 — 1967) grit gritstone Groom Lake Groombridge 34 Groombridge Catalogue gross ground, electrical ground state ground - track group group theory GROUPS AND GROUP THEORY growing season growth growth hormone growth hormone - releasing hormone growth plate 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 G - type asteroid Guericke, Otto von (1602 — 1686) guanine Guiana Space Centre guidance, inertial Guide Star Catalog (GSC) guided missile guided missiles, postwar development Guillaume, Charles Édouard (1861 — 1938) Gulf Stream (ocean current) Gulfstream (jet plane) Gullstrand, Allvar (1862 — 1930) gum Gum Nebula gun metal gunpowder Gurwin Gusev Crater gut Gutenberg, Johann (c. 1400 — 1468) Guy, Richard Kenneth (1916 ---RRB- guyot Guzman Prize gymnosperm gynecology gynoecium gypsum gyrocompass gyrofrequency gyropilot gyroscope gyrostabilizer Gyulbudagian's Nebula (HGamma Cassiopeiae Gamma Cassiopeiae star gamma function gamma globulin gamma rays Gamma Velorum gamma - ray burst gamma - ray satellites Gamow, George (1904 — 1968) ganglion gangrene Ganswindt, Hermann (1856 — 1934) Ganymede «garbage theory», of the origin of life Gardner, Martin (1914 — 2010) Garneau, Marc (1949 ---RRB- garnet Garnet Star (Mu Cephei) Garnet Star Nebula (IC 1396) garnierite Garriott, Owen K. (1930 ---RRB- Garuda gas gas chromatography gas constant gas giant gas laws gas - bounded nebula gaseous nebula gaseous propellant gaseous - propellant rocket engine gasoline Gaspra (minor planet 951) Gassendi, Pierre (1592 — 1655) gastric juice gastrin gastrocnemius gastroenteritis gastrointestinal tract gastropod gastrulation Gatewood, George D. (1940 ---RRB- Gauer - Henry reflex gauge boson gauge theory gauss (unit) Gauss, Carl Friedrich (1777 — 1855) Gaussian distribution Gay - Lussac, Joseph Louis (1778 — 1850) GCOM (Global Change Observing Mission) Geber (c. 720 — 815) gegenschein Geiger, Hans Wilhelm (1882 — 1945) Geiger - Müller counter Giessler tube gel gelatin Gelfond's theorem Gell - Mann, Murray (1929 ---RRB- GEM «gemination,» of martian canals Geminga Gemini (constellation) Gemini Observatory Gemini Project Gemini - Titan II gemstone gene gene expression gene mapping gene pool 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 code genetic counseling genetic disorder genetic drift genetic engineering genetic marker genetic material genetic pool genetic recombination genetics GENETICS AND HEREDITY Geneva Extrasolar Planet Search Program genome genome, interstellar transmission of genotype gentian violet genus geoboard geode geodesic geodesy geodesy satellites geodetic precession Geographos (minor planet 1620) geography GEOGRAPHY Geo - IK geologic time geology GEOLOGY AND PLANETARY SCIENCE geomagnetic field geomagnetic storm geometric mean geometric sequence geometry GEOMETRY geometry puzzles geophysics GEOS (Geodetic Earth Orbiting Satellite) Geosat geostationary orbit geosynchronous orbit geosynchronous / geostationary transfer orbit (GTO) geosyncline Geotail (satellite) geotropism germ germ cells Germain, Sophie (1776 — 1831) German Rocket Society germanium germination Gesner, Konrad von (1516 — 1565) gestation Get Off the Earth puzzle 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 ---RRB- Giacobini - Zinner, Comet (Comet 21P /) Giaever, Ivar (1929 ---RRB- giant branch Giant Magellan Telescope giant molecular cloud giant planet giant star Giant's Causeway Giauque, William Francis (1895 — 1982) gibberellins Gibbs, Josiah Willard (1839 — 1903) Gibbs free energy Gibson, Edward G. (1936 ---RRB- Gilbert, William (1544 — 1603) gilbert (unit) Gilbreath's conjecture gilding gill gill (unit) Gilruth, Robert R. (1913 — 2000) gilsonite gimbal Ginga ginkgo Giotto (ESA Halley probe) GIRD (Gruppa Isutcheniya Reaktivnovo Dvisheniya) girder glacial drift glacial groove glacier gland Glaser, Donald Arthur (1926 — 2013) Glashow, Sheldon (1932 ---RRB- glass GLAST (Gamma - ray Large Area Space Telescope) Glauber, Johann Rudolf (1607 — 1670) glaucoma glauconite Glenn, John Herschel, Jr. (1921 ---RRB- Glenn Research Center Glennan, T (homas) Keith (1905 — 1995) glenoid cavity glia glial cell glider Gliese 229B Gliese 581 Gliese 67 (HD 10307, HIP 7918) Gliese 710 (HD 168442, HIP 89825) Gliese 86 Gliese 876 Gliese Catalogue glioma glissette glitch Global Astrometric Interferometer for Astrophysics (GAIA) Global Oscillation Network Group (GONG) Globalstar globe Globigerina 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 glow - worm glucagon glucocorticoid glucose glucoside gluon Glushko, Valentin Petrovitch (1908 — 1989) glutamic acid glutamine gluten gluteus maximus glycerol glycine glycogen glycol glycolysis glycoprotein glycosidic bond glycosuria glyoxysome GMS (Geosynchronous Meteorological Satellite) GMT (Greenwich Mean Time) Gnathostomata gneiss Go Go, No - go goblet cell GOCE (Gravity field and steady - state Ocean Circulation Explorer) God Goddard, Robert Hutchings (1882 — 1945) Goddard Institute for Space Studies Goddard Space Flight Center Gödel, Kurt (1906 — 1978) Gödel universe Godwin, Francis (1562 — 1633) GOES (Geostationary Operational Environmental Satellite) goethite goiter gold Gold, Thomas (1920 — 2004) Goldbach conjecture golden ratio (phi) Goldin, Daniel Saul (1940 ---RRB- gold - leaf electroscope Goldstone Tracking Facility Golgi, Camillo (1844 — 1926) Golgi apparatus Golomb, Solomon W. (1932 — 2016) golygon GOMS (Geostationary Operational Meteorological Satellite) gonad gonadotrophin - releasing hormone gonadotrophins Gondwanaland Gonets goniatite goniometer gonorrhea Goodricke, John (1764 — 1786) googol Gordian Knot Gordon, Richard Francis, Jr. (1929 — 2017) Gore, John Ellard (1845 — 1910) gorge 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) Graaf, Regnier de (1641 — 1673) Graafian follicle GRAB graben GRACE (Gravity Recovery and Climate Experiment) graceful graph gradient Graham, Ronald (1935 ---RRB- Graham, Thomas (1805 — 1869) Graham's law of diffusion Graham's number GRAIL (Gravity Recovery and Interior Laboratory) grain (cereal) grain (unit) gram gram - atom Gramme, Zénobe Théophile (1826 — 1901) gramophone Gram's stain Gran Telescopio Canarias (GTC) Granat Grand Tour grand unified theory (GUT) Grandfather Paradox Granit, Ragnar Arthur (1900 — 1991) granite granulation granule granulocyte graph graph theory graphene graphite GRAPHS AND GRAPH THEORY graptolite grass grassland gravel graveyard orbit gravimeter gravimetric analysis Gravitational Biology Facility gravitational collapse gravitational constant (G) gravitational instability gravitational lens gravitational life gravitational lock gravitational microlensing GRAVITATIONAL PHYSICS gravitational slingshot effect gravitational waves graviton gravity gravity gradient gravity gradient stabilization Gravity Probe A Gravity Probe B gravity - assist gray (Gy) gray goo gray matter 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 greater omentum greatest elongation Green, George (1793 — 1841) Green, Nathaniel E. Green, Thomas Hill (1836 — 1882) 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, François Auguste Victor (1871 — 1935) Grignard reagent grike Grimaldi, Francesco Maria (1618 — 1663) Grissom, Virgil (1926 — 1967) grit gritstone Groom Lake Groombridge 34 Groombridge Catalogue gross ground, electrical ground state ground - track group group theory GROUPS AND GROUP THEORY growing season growth growth hormone growth hormone - releasing hormone growth plate 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 G - type asteroid Guericke, Otto von (1602 — 1686) guanine Guiana Space Centre guidance, inertial Guide Star Catalog (GSC) guided missile guided missiles, postwar development Guillaume, Charles Édouard (1861 — 1938) Gulf Stream (ocean current) Gulfstream (jet plane) Gullstrand, Allvar (1862 — 1930) gum Gum Nebula gun metal gunpowder Gurwin Gusev Crater gut Gutenberg, Johann (c. 1400 — 1468) Guy, Richard Kenneth (1916 ---RRB- guyot Guzman Prize gymnosperm gynecology gynoecium gypsum gyrocompass gyrofrequency gyropilot gyroscope gyrostabilizer Gyulbudagian's Nebula (HGamma Cassiopeiae star gamma function gamma globulin gamma rays Gamma Velorum gamma - ray burst gamma - ray satellites Gamow, George (1904 — 1968) ganglion gangrene Ganswindt, Hermann (1856 — 1934) Ganymede «garbage theory», of the origin of life Gardner, Martin (1914 — 2010) Garneau, Marc (1949 ---RRB- garnet Garnet Star (Mu Cephei) Garnet Star Nebula (IC 1396) garnierite Garriott, Owen K. (1930 ---RRB- Garuda gas gas chromatography gas constant gas giant gas laws gas - bounded nebula gaseous nebula gaseous propellant gaseous - propellant rocket engine gasoline Gaspra (minor planet 951) Gassendi, Pierre (1592 — 1655) gastric juice gastrin gastrocnemius gastroenteritis gastrointestinal tract gastropod gastrulation Gatewood, George D. (1940 ---RRB- Gauer - Henry reflex gauge boson gauge theory gauss (unit) Gauss, Carl Friedrich (1777 — 1855) Gaussian distribution Gay - Lussac, Joseph Louis (1778 — 1850) GCOM (Global Change Observing Mission) Geber (c. 720 — 815) gegenschein Geiger, Hans Wilhelm (1882 — 1945) Geiger - Müller counter Giessler tube gel gelatin Gelfond's theorem Gell - Mann, Murray (1929 ---RRB- GEM «gemination,» of martian canals Geminga Gemini (constellation) Gemini Observatory Gemini Project Gemini - Titan II gemstone gene gene expression gene mapping gene pool 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 code genetic counseling genetic disorder genetic drift genetic engineering genetic marker genetic material genetic pool genetic recombination genetics GENETICS AND HEREDITY Geneva Extrasolar Planet Search Program genome genome, interstellar transmission of genotype gentian violet genus geoboard geode geodesic geodesy geodesy satellites geodetic precession Geographos (minor planet 1620) geography GEOGRAPHY Geo - IK geologic time geology GEOLOGY AND PLANETARY SCIENCE geomagnetic field geomagnetic storm geometric mean geometric sequence geometry GEOMETRY geometry puzzles geophysics GEOS (Geodetic Earth Orbiting Satellite) Geosat geostationary orbit geosynchronous orbit geosynchronous / geostationary transfer orbit (GTO) geosyncline Geotail (satellite) geotropism germ germ cells Germain, Sophie (1776 — 1831) German Rocket Society germanium germination Gesner, Konrad von (1516 — 1565) gestation Get Off the Earth puzzle 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 ---RRB- Giacobini - Zinner, Comet (Comet 21P /) Giaever, Ivar (1929 ---RRB- giant branch Giant Magellan Telescope giant molecular cloud giant planet giant star Giant's Causeway Giauque, William Francis (1895 — 1982) gibberellins Gibbs, Josiah Willard (1839 — 1903) Gibbs free energy Gibson, Edward G. (1936 ---RRB- Gilbert, William (1544 — 1603) gilbert (unit) Gilbreath's conjecture gilding gill gill (unit) Gilruth, Robert R. (1913 — 2000) gilsonite gimbal Ginga ginkgo Giotto (ESA Halley probe) GIRD (Gruppa Isutcheniya Reaktivnovo Dvisheniya) girder glacial drift glacial groove glacier gland Glaser, Donald Arthur (1926 — 2013) Glashow, Sheldon (1932 ---RRB- glass GLAST (Gamma - ray Large Area Space Telescope) Glauber, Johann Rudolf (1607 — 1670) glaucoma glauconite Glenn, John Herschel, Jr. (1921 ---RRB- Glenn Research Center Glennan, T (homas) Keith (1905 — 1995) glenoid cavity glia glial cell glider Gliese 229B Gliese 581 Gliese 67 (HD 10307, HIP 7918) Gliese 710 (HD 168442, HIP 89825) Gliese 86 Gliese 876 Gliese Catalogue glioma glissette glitch Global Astrometric Interferometer for Astrophysics (GAIA) Global Oscillation Network Group (GONG) Globalstar globe Globigerina 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 glow - worm glucagon glucocorticoid glucose glucoside gluon Glushko, Valentin Petrovitch (1908 — 1989) glutamic acid glutamine gluten gluteus maximus glycerol glycine glycogen glycol glycolysis glycoprotein glycosidic bond glycosuria glyoxysome GMS (Geosynchronous Meteorological Satellite) GMT (Greenwich Mean Time) Gnathostomata gneiss Go Go, No - go goblet cell GOCE (Gravity field and steady - state Ocean Circulation Explorer) God Goddard, Robert Hutchings (1882 — 1945) Goddard Institute for Space Studies Goddard Space Flight Center Gödel, Kurt (1906 — 1978) Gödel universe Godwin, Francis (1562 — 1633) GOES (Geostationary Operational Environmental Satellite) goethite goiter gold Gold, Thomas (1920 — 2004) Goldbach conjecture golden ratio (phi) Goldin, Daniel Saul (1940 ---RRB- gold - leaf electroscope Goldstone Tracking Facility Golgi, Camillo (1844 — 1926) Golgi apparatus Golomb, Solomon W. (1932 — 2016) golygon GOMS (Geostationary Operational Meteorological Satellite) gonad gonadotrophin - releasing hormone gonadotrophins Gondwanaland Gonets goniatite goniometer gonorrhea Goodricke, John (1764 — 1786) googol Gordian Knot Gordon, Richard Francis, Jr. (1929 — 2017) Gore, John Ellard (1845 — 1910) gorge 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) Graaf, Regnier de (1641 — 1673) Graafian follicle GRAB graben GRACE (Gravity Recovery and Climate Experiment) graceful graph gradient Graham, Ronald (1935 ---RRB- Graham, Thomas (1805 — 1869) Graham's law of diffusion Graham's number GRAIL (Gravity Recovery and Interior Laboratory) grain (cereal) grain (unit) gram gram - atom Gramme, Zénobe Théophile (1826 — 1901) gramophone Gram's stain Gran Telescopio Canarias (GTC) Granat Grand Tour grand unified theory (GUT) Grandfather Paradox Granit, Ragnar Arthur (1900 — 1991) granite granulation granule granulocyte graph graph theory graphene graphite GRAPHS AND GRAPH THEORY graptolite grass grassland gravel graveyard orbit gravimeter gravimetric analysis Gravitational Biology Facility gravitational collapse gravitational constant (G) gravitational instability gravitational lens gravitational life gravitational lock gravitational microlensing GRAVITATIONAL PHYSICS gravitational slingshot effect gravitational waves graviton gravity gravity gradient gravity gradient stabilization Gravity Probe A Gravity Probe B gravity - assist gray (Gy) gray goo gray matter 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 greater omentum greatest elongation Green, George (1793 — 1841) Green, Nathaniel E. Green, Thomas Hill (1836 — 1882) 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, François Auguste Victor (1871 — 1935) Grignard reagent grike Grimaldi, Francesco Maria (1618 — 1663) Grissom, Virgil (1926 — 1967) grit gritstone Groom Lake Groombridge 34 Groombridge Catalogue gross ground, electrical ground state ground - track group group theory GROUPS AND GROUP THEORY growing season growth growth hormone growth hormone - releasing hormone growth plate 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 G - type asteroid Guericke, Otto von (1602 — 1686) guanine Guiana Space Centre guidance, inertial Guide Star Catalog (GSC) guided missile guided missiles, postwar development Guillaume, Charles Édouard (1861 — 1938) Gulf Stream (ocean current) Gulfstream (jet plane) Gullstrand, Allvar (1862 — 1930) gum Gum Nebula gun metal gunpowder Gurwin Gusev Crater gut Gutenberg, Johann (c. 1400 — 1468) Guy, Richard Kenneth (1916 ---RRB- guyot Guzman Prize gymnosperm gynecology gynoecium gypsum gyrocompass gyrofrequency gyropilot gyroscope gyrostabilizer Gyulbudagian's Nebula (Hgamma function gamma globulin gamma rays Gamma Velorum gamma - ray burst gamma - ray satellites Gamow, George (1904 — 1968) ganglion gangrene Ganswindt, Hermann (1856 — 1934) Ganymede «garbage theory», of the origin of life Gardner, Martin (1914 — 2010) Garneau, Marc (1949 ---RRB- garnet Garnet Star (Mu Cephei) Garnet Star Nebula (IC 1396) garnierite Garriott, Owen K. (1930 ---RRB- Garuda gas gas chromatography gas constant gas giant gas laws gas - bounded nebula gaseous nebula gaseous propellant gaseous - propellant rocket engine gasoline Gaspra (minor planet 951) Gassendi, Pierre (1592 — 1655) gastric juice gastrin gastrocnemius gastroenteritis gastrointestinal tract gastropod gastrulation Gatewood, George D. (1940 ---RRB- Gauer - Henry reflex gauge boson gauge theory gauss (unit) Gauss, Carl Friedrich (1777 — 1855) Gaussian distribution Gay - Lussac, Joseph Louis (1778 — 1850) GCOM (Global Change Observing Mission) Geber (c. 720 — 815) gegenschein Geiger, Hans Wilhelm (1882 — 1945) Geiger - Müller counter Giessler tube gel gelatin Gelfond's theorem Gell - Mann, Murray (1929 ---RRB- GEM «gemination,» of martian canals Geminga Gemini (constellation) Gemini Observatory Gemini Project Gemini - Titan II gemstone gene gene expression gene mapping gene pool 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 code genetic counseling genetic disorder genetic drift genetic engineering genetic marker genetic material genetic pool genetic recombination genetics GENETICS AND HEREDITY Geneva Extrasolar Planet Search Program genome genome, interstellar transmission of genotype gentian violet genus geoboard geode geodesic geodesy geodesy satellites geodetic precession Geographos (minor planet 1620) geography GEOGRAPHY Geo - IK geologic time geology GEOLOGY AND PLANETARY SCIENCE geomagnetic field geomagnetic storm geometric mean geometric sequence geometry GEOMETRY geometry puzzles geophysics GEOS (Geodetic Earth Orbiting Satellite) Geosat geostationary orbit geosynchronous orbit geosynchronous / geostationary transfer orbit (GTO) geosyncline Geotail (satellite) geotropism germ germ cells Germain, Sophie (1776 — 1831) German Rocket Society germanium germination Gesner, Konrad von (1516 — 1565) gestation Get Off the Earth puzzle 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 ---RRB- Giacobini - Zinner, Comet (Comet 21P /) Giaever, Ivar (1929 ---RRB- giant branch Giant Magellan Telescope giant molecular cloud giant planet giant star Giant's Causeway Giauque, William Francis (1895 — 1982) gibberellins Gibbs, Josiah Willard (1839 — 1903) Gibbs free energy Gibson, Edward G. (1936 ---RRB- Gilbert, William (1544 — 1603) gilbert (unit) Gilbreath's conjecture gilding gill gill (unit) Gilruth, Robert R. (1913 — 2000) gilsonite gimbal Ginga ginkgo Giotto (ESA Halley probe) GIRD (Gruppa Isutcheniya Reaktivnovo Dvisheniya) girder glacial drift glacial groove glacier gland Glaser, Donald Arthur (1926 — 2013) Glashow, Sheldon (1932 ---RRB- glass GLAST (Gamma - ray Large Area Space Telescope) Glauber, Johann Rudolf (1607 — 1670) glaucoma glauconite Glenn, John Herschel, Jr. (1921 ---RRB- Glenn Research Center Glennan, T (homas) Keith (1905 — 1995) glenoid cavity glia glial cell glider Gliese 229B Gliese 581 Gliese 67 (HD 10307, HIP 7918) Gliese 710 (HD 168442, HIP 89825) Gliese 86 Gliese 876 Gliese Catalogue glioma glissette glitch Global Astrometric Interferometer for Astrophysics (GAIA) Global Oscillation Network Group (GONG) Globalstar globe Globigerina 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 glow - worm glucagon glucocorticoid glucose glucoside gluon Glushko, Valentin Petrovitch (1908 — 1989) glutamic acid glutamine gluten gluteus maximus glycerol glycine glycogen glycol glycolysis glycoprotein glycosidic bond glycosuria glyoxysome GMS (Geosynchronous Meteorological Satellite) GMT (Greenwich Mean Time) Gnathostomata gneiss Go Go, No - go goblet cell GOCE (Gravity field and steady - state Ocean Circulation Explorer) God Goddard, Robert Hutchings (1882 — 1945) Goddard Institute for Space Studies Goddard Space Flight Center Gödel, Kurt (1906 — 1978) Gödel universe Godwin, Francis (1562 — 1633) GOES (Geostationary Operational Environmental Satellite) goethite goiter gold Gold, Thomas (1920 — 2004) Goldbach conjecture golden ratio (phi) Goldin, Daniel Saul (1940 ---RRB- gold - leaf electroscope Goldstone Tracking Facility Golgi, Camillo (1844 — 1926) Golgi apparatus Golomb, Solomon W. (1932 — 2016) golygon GOMS (Geostationary Operational Meteorological Satellite) gonad gonadotrophin - releasing hormone gonadotrophins Gondwanaland Gonets goniatite goniometer gonorrhea Goodricke, John (1764 — 1786) googol Gordian Knot Gordon, Richard Francis, Jr. (1929 — 2017) Gore, John Ellard (1845 — 1910) gorge 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) Graaf, Regnier de (1641 — 1673) Graafian follicle GRAB graben GRACE (Gravity Recovery and Climate Experiment) graceful graph gradient Graham, Ronald (1935 ---RRB- Graham, Thomas (1805 — 1869) Graham's law of diffusion Graham's number GRAIL (Gravity Recovery and Interior Laboratory) grain (cereal) grain (unit) gram gram - atom Gramme, Zénobe Théophile (1826 — 1901) gramophone Gram's stain Gran Telescopio Canarias (GTC) Granat Grand Tour grand unified theory (GUT) Grandfather Paradox Granit, Ragnar Arthur (1900 — 1991) granite granulation granule granulocyte graph graph theory graphene graphite GRAPHS AND GRAPH THEORY graptolite grass grassland gravel graveyard orbit gravimeter gravimetric analysis Gravitational Biology Facility gravitational collapse gravitational constant (G) gravitational instability gravitational lens gravitational life gravitational lock gravitational microlensing GRAVITATIONAL PHYSICS gravitational slingshot effect gravitational waves graviton gravity gravity gradient gravity gradient stabilization Gravity Probe A Gravity Probe B gravity - assist gray (Gy) gray goo gray matter 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 greater omentum greatest elongation Green, George (1793 — 1841) Green, Nathaniel E. Green, Thomas Hill (1836 — 1882) 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, François Auguste Victor (1871 — 1935) Grignard reagent grike Grimaldi, Francesco Maria (1618 — 1663) Grissom, Virgil (1926 — 1967) grit gritstone Groom Lake Groombridge 34 Groombridge Catalogue gross ground, electrical ground state ground - track group group theory GROUPS AND GROUP THEORY growing season growth growth hormone growth hormone - releasing hormone growth plate 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 G - type asteroid Guericke, Otto von (1602 — 1686) guanine Guiana Space Centre guidance, inertial Guide Star Catalog (GSC) guided missile guided missiles, postwar development Guillaume, Charles Édouard (1861 — 1938) Gulf Stream (ocean current) Gulfstream (jet plane) Gullstrand, Allvar (1862 — 1930) gum Gum Nebula gun metal gunpowder Gurwin Gusev Crater gut Gutenberg, Johann (c. 1400 — 1468) Guy, Richard Kenneth (1916 ---RRB- guyot Guzman Prize gymnosperm gynecology gynoecium gypsum gyrocompass gyrofrequency gyropilot gyroscope gyrostabilizer Gyulbudagian's Nebula (Hgamma globulin gamma rays Gamma Velorum gamma - ray burst gamma - ray satellites Gamow, George (1904 — 1968) ganglion gangrene Ganswindt, Hermann (1856 — 1934) Ganymede «garbage theory», of the origin of life Gardner, Martin (1914 — 2010) Garneau, Marc (1949 ---RRB- garnet Garnet Star (Mu Cephei) Garnet Star Nebula (IC 1396) garnierite Garriott, Owen K. (1930 ---RRB- Garuda gas gas chromatography gas constant gas giant gas laws gas - bounded nebula gaseous nebula gaseous propellant gaseous - propellant rocket engine gasoline Gaspra (minor planet 951) Gassendi, Pierre (1592 — 1655) gastric juice gastrin gastrocnemius gastroenteritis gastrointestinal tract gastropod gastrulation Gatewood, George D. (1940 ---RRB- Gauer - Henry reflex gauge boson gauge theory gauss (unit) Gauss, Carl Friedrich (1777 — 1855) Gaussian distribution Gay - Lussac, Joseph Louis (1778 — 1850) GCOM (Global Change Observing Mission) Geber (c. 720 — 815) gegenschein Geiger, Hans Wilhelm (1882 — 1945) Geiger - Müller counter Giessler tube gel gelatin Gelfond's theorem Gell - Mann, Murray (1929 ---RRB- GEM «gemination,» of martian canals Geminga Gemini (constellation) Gemini Observatory Gemini Project Gemini - Titan II gemstone gene gene expression gene mapping gene pool 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 code genetic counseling genetic disorder genetic drift genetic engineering genetic marker genetic material genetic pool genetic recombination genetics GENETICS AND HEREDITY Geneva Extrasolar Planet Search Program genome genome, interstellar transmission of genotype gentian violet genus geoboard geode geodesic geodesy geodesy satellites geodetic precession Geographos (minor planet 1620) geography GEOGRAPHY Geo - IK geologic time geology GEOLOGY AND PLANETARY SCIENCE geomagnetic field geomagnetic storm geometric mean geometric sequence geometry GEOMETRY geometry puzzles geophysics GEOS (Geodetic Earth Orbiting Satellite) Geosat geostationary orbit geosynchronous orbit geosynchronous / geostationary transfer orbit (GTO) geosyncline Geotail (satellite) geotropism germ germ cells Germain, Sophie (1776 — 1831) German Rocket Society germanium germination Gesner, Konrad von (1516 — 1565) gestation Get Off the Earth puzzle 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 ---RRB- Giacobini - Zinner, Comet (Comet 21P /) Giaever, Ivar (1929 ---RRB- giant branch Giant Magellan Telescope giant molecular cloud giant planet giant star Giant's Causeway Giauque, William Francis (1895 — 1982) gibberellins Gibbs, Josiah Willard (1839 — 1903) Gibbs free energy Gibson, Edward G. (1936 ---RRB- Gilbert, William (1544 — 1603) gilbert (unit) Gilbreath's conjecture gilding gill gill (unit) Gilruth, Robert R. (1913 — 2000) gilsonite gimbal Ginga ginkgo Giotto (ESA Halley probe) GIRD (Gruppa Isutcheniya Reaktivnovo Dvisheniya) girder glacial drift glacial groove glacier gland Glaser, Donald Arthur (1926 — 2013) Glashow, Sheldon (1932 ---RRB- glass GLAST (Gamma - ray Large Area Space Telescope) Glauber, Johann Rudolf (1607 — 1670) glaucoma glauconite Glenn, John Herschel, Jr. (1921 ---RRB- Glenn Research Center Glennan, T (homas) Keith (1905 — 1995) glenoid cavity glia glial cell glider Gliese 229B Gliese 581 Gliese 67 (HD 10307, HIP 7918) Gliese 710 (HD 168442, HIP 89825) Gliese 86 Gliese 876 Gliese Catalogue glioma glissette glitch Global Astrometric Interferometer for Astrophysics (GAIA) Global Oscillation Network Group (GONG) Globalstar globe Globigerina 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 glow - worm glucagon glucocorticoid glucose glucoside gluon Glushko, Valentin Petrovitch (1908 — 1989) glutamic acid glutamine gluten gluteus maximus glycerol glycine glycogen glycol glycolysis glycoprotein glycosidic bond glycosuria glyoxysome GMS (Geosynchronous Meteorological Satellite) GMT (Greenwich Mean Time) Gnathostomata gneiss Go Go, No - go goblet cell GOCE (Gravity field and steady - state Ocean Circulation Explorer) God Goddard, Robert Hutchings (1882 — 1945) Goddard Institute for Space Studies Goddard Space Flight Center Gödel, Kurt (1906 — 1978) Gödel universe Godwin, Francis (1562 — 1633) GOES (Geostationary Operational Environmental Satellite) goethite goiter gold Gold, Thomas (1920 — 2004) Goldbach conjecture golden ratio (phi) Goldin, Daniel Saul (1940 ---RRB- gold - leaf electroscope Goldstone Tracking Facility Golgi, Camillo (1844 — 1926) Golgi apparatus Golomb, Solomon W. (1932 — 2016) golygon GOMS (Geostationary Operational Meteorological Satellite) gonad gonadotrophin - releasing hormone gonadotrophins Gondwanaland Gonets goniatite goniometer gonorrhea Goodricke, John (1764 — 1786) googol Gordian Knot Gordon, Richard Francis, Jr. (1929 — 2017) Gore, John Ellard (1845 — 1910) gorge 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) Graaf, Regnier de (1641 — 1673) Graafian follicle GRAB graben GRACE (Gravity Recovery and Climate Experiment) graceful graph gradient Graham, Ronald (1935 ---RRB- Graham, Thomas (1805 — 1869) Graham's law of diffusion Graham's number GRAIL (Gravity Recovery and Interior Laboratory) grain (cereal) grain (unit) gram gram - atom Gramme, Zénobe Théophile (1826 — 1901) gramophone Gram's stain Gran Telescopio Canarias (GTC) Granat Grand Tour grand unified theory (GUT) Grandfather Paradox Granit, Ragnar Arthur (1900 — 1991) granite granulation granule granulocyte graph graph theory graphene graphite GRAPHS AND GRAPH THEORY graptolite grass grassland gravel graveyard orbit gravimeter gravimetric analysis Gravitational Biology Facility gravitational collapse gravitational constant (G) gravitational instability gravitational lens gravitational life gravitational lock gravitational microlensing GRAVITATIONAL PHYSICS gravitational slingshot effect gravitational waves graviton gravity gravity gradient gravity gradient stabilization Gravity Probe A Gravity Probe B gravity - assist gray (Gy) gray goo gray matter 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 greater omentum greatest elongation Green, George (1793 — 1841) Green, Nathaniel E. Green, Thomas Hill (1836 — 1882) 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, François Auguste Victor (1871 — 1935) Grignard reagent grike Grimaldi, Francesco Maria (1618 — 1663) Grissom, Virgil (1926 — 1967) grit gritstone Groom Lake Groombridge 34 Groombridge Catalogue gross ground, electrical ground state ground - track group group theory GROUPS AND GROUP THEORY growing season growth growth hormone growth hormone - releasing hormone growth plate 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 G - type asteroid Guericke, Otto von (1602 — 1686) guanine Guiana Space Centre guidance, inertial Guide Star Catalog (GSC) guided missile guided missiles, postwar development Guillaume, Charles Édouard (1861 — 1938) Gulf Stream (ocean current) Gulfstream (jet plane) Gullstrand, Allvar (1862 — 1930) gum Gum Nebula gun metal gunpowder Gurwin Gusev Crater gut Gutenberg, Johann (c. 1400 — 1468) Guy, Richard Kenneth (1916 ---RRB- guyot Guzman Prize gymnosperm gynecology gynoecium gypsum gyrocompass gyrofrequency gyropilot gyroscope gyrostabilizer Gyulbudagian's Nebula (Hgamma rays Gamma Velorum gamma - ray burst gamma - ray satellites Gamow, George (1904 — 1968) ganglion gangrene Ganswindt, Hermann (1856 — 1934) Ganymede «garbage theory», of the origin of life Gardner, Martin (1914 — 2010) Garneau, Marc (1949 ---RRB- garnet Garnet Star (Mu Cephei) Garnet Star Nebula (IC 1396) garnierite Garriott, Owen K. (1930 ---RRB- Garuda gas gas chromatography gas constant gas giant gas laws gas - bounded nebula gaseous nebula gaseous propellant gaseous - propellant rocket engine gasoline Gaspra (minor planet 951) Gassendi, Pierre (1592 — 1655) gastric juice gastrin gastrocnemius gastroenteritis gastrointestinal tract gastropod gastrulation Gatewood, George D. (1940 ---RRB- Gauer - Henry reflex gauge boson gauge theory gauss (unit) Gauss, Carl Friedrich (1777 — 1855) Gaussian distribution Gay - Lussac, Joseph Louis (1778 — 1850) GCOM (Global Change Observing Mission) Geber (c. 720 — 815) gegenschein Geiger, Hans Wilhelm (1882 — 1945) Geiger - Müller counter Giessler tube gel gelatin Gelfond's theorem Gell - Mann, Murray (1929 ---RRB- GEM «gemination,» of martian canals Geminga Gemini (constellation) Gemini Observatory Gemini Project Gemini - Titan II gemstone gene gene expression gene mapping gene pool 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 code genetic counseling genetic disorder genetic drift genetic engineering genetic marker genetic material genetic pool genetic recombination genetics GENETICS AND HEREDITY Geneva Extrasolar Planet Search Program genome genome, interstellar transmission of genotype gentian violet genus geoboard geode geodesic geodesy geodesy satellites geodetic precession Geographos (minor planet 1620) geography GEOGRAPHY Geo - IK geologic time geology GEOLOGY AND PLANETARY SCIENCE geomagnetic field geomagnetic storm geometric mean geometric sequence geometry GEOMETRY geometry puzzles geophysics GEOS (Geodetic Earth Orbiting Satellite) Geosat geostationary orbit geosynchronous orbit geosynchronous / geostationary transfer orbit (GTO) geosyncline Geotail (satellite) geotropism germ germ cells Germain, Sophie (1776 — 1831) German Rocket Society germanium germination Gesner, Konrad von (1516 — 1565) gestation Get Off the Earth puzzle 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 ---RRB- Giacobini - Zinner, Comet (Comet 21P /) Giaever, Ivar (1929 ---RRB- giant branch Giant Magellan Telescope giant molecular cloud giant planet giant star Giant's Causeway Giauque, William Francis (1895 — 1982) gibberellins Gibbs, Josiah Willard (1839 — 1903) Gibbs free energy Gibson, Edward G. (1936 ---RRB- Gilbert, William (1544 — 1603) gilbert (unit) Gilbreath's conjecture gilding gill gill (unit) Gilruth, Robert R. (1913 — 2000) gilsonite gimbal Ginga ginkgo Giotto (ESA Halley probe) GIRD (Gruppa Isutcheniya Reaktivnovo Dvisheniya) girder glacial drift glacial groove glacier gland Glaser, Donald Arthur (1926 — 2013) Glashow, Sheldon (1932 ---RRB- glass GLAST (Gamma - ray Large Area Space Telescope) Glauber, Johann Rudolf (1607 — 1670) glaucoma glauconite Glenn, John Herschel, Jr. (1921 ---RRB- Glenn Research Center Glennan, T (homas) Keith (1905 — 1995) glenoid cavity glia glial cell glider Gliese 229B Gliese 581 Gliese 67 (HD 10307, HIP 7918) Gliese 710 (HD 168442, HIP 89825) Gliese 86 Gliese 876 Gliese Catalogue glioma glissette glitch Global Astrometric Interferometer for Astrophysics (GAIA) Global Oscillation Network Group (GONG) Globalstar globe Globigerina 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 glow - worm glucagon glucocorticoid glucose glucoside gluon Glushko, Valentin Petrovitch (1908 — 1989) glutamic acid glutamine gluten gluteus maximus glycerol glycine glycogen glycol glycolysis glycoprotein glycosidic bond glycosuria glyoxysome GMS (Geosynchronous Meteorological Satellite) GMT (Greenwich Mean Time) Gnathostomata gneiss Go Go, No - go goblet cell GOCE (Gravity field and steady - state Ocean Circulation Explorer) God Goddard, Robert Hutchings (1882 — 1945) Goddard Institute for Space Studies Goddard Space Flight Center Gödel, Kurt (1906 — 1978) Gödel universe Godwin, Francis (1562 — 1633) GOES (Geostationary Operational Environmental Satellite) goethite goiter gold Gold, Thomas (1920 — 2004) Goldbach conjecture golden ratio (phi) Goldin, Daniel Saul (1940 ---RRB- gold - leaf electroscope Goldstone Tracking Facility Golgi, Camillo (1844 — 1926) Golgi apparatus Golomb, Solomon W. (1932 — 2016) golygon GOMS (Geostationary Operational Meteorological Satellite) gonad gonadotrophin - releasing hormone gonadotrophins Gondwanaland Gonets goniatite goniometer gonorrhea Goodricke, John (1764 — 1786) googol Gordian Knot Gordon, Richard Francis, Jr. (1929 — 2017) Gore, John Ellard (1845 — 1910) gorge 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) Graaf, Regnier de (1641 — 1673) Graafian follicle GRAB graben GRACE (Gravity Recovery and Climate Experiment) graceful graph gradient Graham, Ronald (1935 ---RRB- Graham, Thomas (1805 — 1869) Graham's law of diffusion Graham's number GRAIL (Gravity Recovery and Interior Laboratory) grain (cereal) grain (unit) gram gram - atom Gramme, Zénobe Théophile (1826 — 1901) gramophone Gram's stain Gran Telescopio Canarias (GTC) Granat Grand Tour grand unified theory (GUT) Grandfather Paradox Granit, Ragnar Arthur (1900 — 1991) granite granulation granule granulocyte graph graph theory graphene graphite GRAPHS AND GRAPH THEORY graptolite grass grassland gravel graveyard orbit gravimeter gravimetric analysis Gravitational Biology Facility gravitational collapse gravitational constant (G) gravitational instability gravitational lens gravitational life gravitational lock gravitational microlensing GRAVITATIONAL PHYSICS gravitational slingshot effect gravitational waves graviton gravity gravity gradient gravity gradient stabilization Gravity Probe A Gravity Probe B gravity - assist gray (Gy) gray goo gray matter 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 greater omentum greatest elongation Green, George (1793 — 1841) Green, Nathaniel E. Green, Thomas Hill (1836 — 1882) 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, François Auguste Victor (1871 — 1935) Grignard reagent grike Grimaldi, Francesco Maria (1618 — 1663) Grissom, Virgil (1926 — 1967) grit gritstone Groom Lake Groombridge 34 Groombridge Catalogue gross ground, electrical ground state ground - track group group theory GROUPS AND GROUP THEORY growing season growth growth hormone growth hormone - releasing hormone growth plate 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 G - type asteroid Guericke, Otto von (1602 — 1686) guanine Guiana Space Centre guidance, inertial Guide Star Catalog (GSC) guided missile guided missiles, postwar development Guillaume, Charles Édouard (1861 — 1938) Gulf Stream (ocean current) Gulfstream (jet plane) Gullstrand, Allvar (1862 — 1930) gum Gum Nebula gun metal gunpowder Gurwin Gusev Crater gut Gutenberg, Johann (c. 1400 — 1468) Guy, Richard Kenneth (1916 ---RRB- guyot Guzman Prize gymnosperm gynecology gynoecium gypsum gyrocompass gyrofrequency gyropilot gyroscope gyrostabilizer Gyulbudagian's Nebula (HGamma Velorum gamma - ray burst gamma - ray satellites Gamow, George (1904 — 1968) ganglion gangrene Ganswindt, Hermann (1856 — 1934) Ganymede «garbage theory», of the origin of life Gardner, Martin (1914 — 2010) Garneau, Marc (1949 ---RRB- garnet Garnet Star (Mu Cephei) Garnet Star Nebula (IC 1396) garnierite Garriott, Owen K. (1930 ---RRB- Garuda gas gas chromatography gas constant gas giant gas laws gas - bounded nebula gaseous nebula gaseous propellant gaseous - propellant rocket engine gasoline Gaspra (minor planet 951) Gassendi, Pierre (1592 — 1655) gastric juice gastrin gastrocnemius gastroenteritis gastrointestinal tract gastropod gastrulation Gatewood, George D. (1940 ---RRB- Gauer - Henry reflex gauge boson gauge theory gauss (unit) Gauss, Carl Friedrich (1777 — 1855) Gaussian distribution Gay - Lussac, Joseph Louis (1778 — 1850) GCOM (Global Change Observing Mission) Geber (c. 720 — 815) gegenschein Geiger, Hans Wilhelm (1882 — 1945) Geiger - Müller counter Giessler tube gel gelatin Gelfond's theorem Gell - Mann, Murray (1929 ---RRB- GEM «gemination,» of martian canals Geminga Gemini (constellation) Gemini Observatory Gemini Project Gemini - Titan II gemstone gene gene expression gene mapping gene pool 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 code genetic counseling genetic disorder genetic drift genetic engineering genetic marker genetic material genetic pool genetic recombination genetics GENETICS AND HEREDITY Geneva Extrasolar Planet Search Program genome genome, interstellar transmission of genotype gentian violet genus geoboard geode geodesic geodesy geodesy satellites geodetic precession Geographos (minor planet 1620) geography GEOGRAPHY Geo - IK geologic time geology GEOLOGY AND PLANETARY SCIENCE geomagnetic field geomagnetic storm geometric mean geometric sequence geometry GEOMETRY geometry puzzles geophysics GEOS (Geodetic Earth Orbiting Satellite) Geosat geostationary orbit geosynchronous orbit geosynchronous / geostationary transfer orbit (GTO) geosyncline Geotail (satellite) geotropism germ germ cells Germain, Sophie (1776 — 1831) German Rocket Society germanium germination Gesner, Konrad von (1516 — 1565) gestation Get Off the Earth puzzle 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 ---RRB- Giacobini - Zinner, Comet (Comet 21P /) Giaever, Ivar (1929 ---RRB- giant branch Giant Magellan Telescope giant molecular cloud giant planet giant star Giant's Causeway Giauque, William Francis (1895 — 1982) gibberellins Gibbs, Josiah Willard (1839 — 1903) Gibbs free energy Gibson, Edward G. (1936 ---RRB- Gilbert, William (1544 — 1603) gilbert (unit) Gilbreath's conjecture gilding gill gill (unit) Gilruth, Robert R. (1913 — 2000) gilsonite gimbal Ginga ginkgo Giotto (ESA Halley probe) GIRD (Gruppa Isutcheniya Reaktivnovo Dvisheniya) girder glacial drift glacial groove glacier gland Glaser, Donald Arthur (1926 — 2013) Glashow, Sheldon (1932 ---RRB- glass GLAST (Gamma - ray Large Area Space Telescope) Glauber, Johann Rudolf (1607 — 1670) glaucoma glauconite Glenn, John Herschel, Jr. (1921 ---RRB- Glenn Research Center Glennan, T (homas) Keith (1905 — 1995) glenoid cavity glia glial cell glider Gliese 229B Gliese 581 Gliese 67 (HD 10307, HIP 7918) Gliese 710 (HD 168442, HIP 89825) Gliese 86 Gliese 876 Gliese Catalogue glioma glissette glitch Global Astrometric Interferometer for Astrophysics (GAIA) Global Oscillation Network Group (GONG) Globalstar globe Globigerina 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 glow - worm glucagon glucocorticoid glucose glucoside gluon Glushko, Valentin Petrovitch (1908 — 1989) glutamic acid glutamine gluten gluteus maximus glycerol glycine glycogen glycol glycolysis glycoprotein glycosidic bond glycosuria glyoxysome GMS (Geosynchronous Meteorological Satellite) GMT (Greenwich Mean Time) Gnathostomata gneiss Go Go, No - go goblet cell GOCE (Gravity field and steady - state Ocean Circulation Explorer) God Goddard, Robert Hutchings (1882 — 1945) Goddard Institute for Space Studies Goddard Space Flight Center Gödel, Kurt (1906 — 1978) Gödel universe Godwin, Francis (1562 — 1633) GOES (Geostationary Operational Environmental Satellite) goethite goiter gold Gold, Thomas (1920 — 2004) Goldbach conjecture golden ratio (phi) Goldin, Daniel Saul (1940 ---RRB- gold - leaf electroscope Goldstone Tracking Facility Golgi, Camillo (1844 — 1926) Golgi apparatus Golomb, Solomon W. (1932 — 2016) golygon GOMS (Geostationary Operational Meteorological Satellite) gonad gonadotrophin - releasing hormone gonadotrophins Gondwanaland Gonets goniatite goniometer gonorrhea Goodricke, John (1764 — 1786) googol Gordian Knot Gordon, Richard Francis, Jr. (1929 — 2017) Gore, John Ellard (1845 — 1910) gorge 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) Graaf, Regnier de (1641 — 1673) Graafian follicle GRAB graben GRACE (Gravity Recovery and Climate Experiment) graceful graph gradient Graham, Ronald (1935 ---RRB- Graham, Thomas (1805 — 1869) Graham's law of diffusion Graham's number GRAIL (Gravity Recovery and Interior Laboratory) grain (cereal) grain (unit) gram gram - atom Gramme, Zénobe Théophile (1826 — 1901) gramophone Gram's stain Gran Telescopio Canarias (GTC) Granat Grand Tour grand unified theory (GUT) Grandfather Paradox Granit, Ragnar Arthur (1900 — 1991) granite granulation granule granulocyte graph graph theory graphene graphite GRAPHS AND GRAPH THEORY graptolite grass grassland gravel graveyard orbit gravimeter gravimetric analysis Gravitational Biology Facility gravitational collapse gravitational constant (G) gravitational instability gravitational lens gravitational life gravitational lock gravitational microlensing GRAVITATIONAL PHYSICS gravitational slingshot effect gravitational waves graviton gravity gravity gradient gravity gradient stabilization Gravity Probe A Gravity Probe B gravity - assist gray (Gy) gray goo gray matter 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 greater omentum greatest elongation Green, George (1793 — 1841) Green, Nathaniel E. Green, Thomas Hill (1836 — 1882) 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, François Auguste Victor (1871 — 1935) Grignard reagent grike Grimaldi, Francesco Maria (1618 — 1663) Grissom, Virgil (1926 — 1967) grit gritstone Groom Lake Groombridge 34 Groombridge Catalogue gross ground, electrical ground state ground - track group group theory GROUPS AND GROUP THEORY growing season growth growth hormone growth hormone - releasing hormone growth plate 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 G - type asteroid Guericke, Otto von (1602 — 1686) guanine Guiana Space Centre guidance, inertial Guide Star Catalog (GSC) guided missile guided missiles, postwar development Guillaume, Charles Édouard (1861 — 1938) Gulf Stream (ocean current) Gulfstream (jet plane) Gullstrand, Allvar (1862 — 1930) gum Gum Nebula gun metal gunpowder Gurwin Gusev Crater gut Gutenberg, Johann (c. 1400 — 1468) Guy, Richard Kenneth (1916 ---RRB- guyot Guzman Prize gymnosperm gynecology gynoecium gypsum gyrocompass gyrofrequency gyropilot gyroscope gyrostabilizer Gyulbudagian's Nebula (Hgamma - ray burst gamma - ray satellites Gamow, George (1904 — 1968) ganglion gangrene Ganswindt, Hermann (1856 — 1934) Ganymede «garbage theory», of the origin of life Gardner, Martin (1914 — 2010) Garneau, Marc (1949 ---RRB- garnet Garnet Star (Mu Cephei) Garnet Star Nebula (IC 1396) garnierite Garriott, Owen K. (1930 ---RRB- Garuda gas gas chromatography gas constant gas giant gas laws gas - bounded nebula gaseous nebula gaseous propellant gaseous - propellant rocket engine gasoline Gaspra (minor planet 951) Gassendi, Pierre (1592 — 1655) gastric juice gastrin gastrocnemius gastroenteritis gastrointestinal tract gastropod gastrulation Gatewood, George D. (1940 ---RRB- Gauer - Henry reflex gauge boson gauge theory gauss (unit) Gauss, Carl Friedrich (1777 — 1855) Gaussian distribution Gay - Lussac, Joseph Louis (1778 — 1850) GCOM (Global Change Observing Mission) Geber (c. 720 — 815) gegenschein Geiger, Hans Wilhelm (1882 — 1945) Geiger - Müller counter Giessler tube gel gelatin Gelfond's theorem Gell - Mann, Murray (1929 ---RRB- GEM «gemination,» of martian canals Geminga Gemini (constellation) Gemini Observatory Gemini Project Gemini - Titan II gemstone gene gene expression gene mapping gene pool 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 code genetic counseling genetic disorder genetic drift genetic engineering genetic marker genetic material genetic pool genetic recombination genetics GENETICS AND HEREDITY Geneva Extrasolar Planet Search Program genome genome, interstellar transmission of genotype gentian violet genus geoboard geode geodesic geodesy geodesy satellites geodetic precession Geographos (minor planet 1620) geography GEOGRAPHY Geo - IK geologic time geology GEOLOGY AND PLANETARY SCIENCE geomagnetic field geomagnetic storm geometric mean geometric sequence geometry GEOMETRY geometry puzzles geophysics GEOS (Geodetic Earth Orbiting Satellite) Geosat geostationary orbit geosynchronous orbit geosynchronous / geostationary transfer orbit (GTO) geosyncline Geotail (satellite) geotropism germ germ cells Germain, Sophie (1776 — 1831) German Rocket Society germanium germination Gesner, Konrad von (1516 — 1565) gestation Get Off the Earth puzzle 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 ---RRB- Giacobini - Zinner, Comet (Comet 21P /) Giaever, Ivar (1929 ---RRB- giant branch Giant Magellan Telescope giant molecular cloud giant planet giant star Giant's Causeway Giauque, William Francis (1895 — 1982) gibberellins Gibbs, Josiah Willard (1839 — 1903) Gibbs free energy Gibson, Edward G. (1936 ---RRB- Gilbert, William (1544 — 1603) gilbert (unit) Gilbreath's conjecture gilding gill gill (unit) Gilruth, Robert R. (1913 — 2000) gilsonite gimbal Ginga ginkgo Giotto (ESA Halley probe) GIRD (Gruppa Isutcheniya Reaktivnovo Dvisheniya) girder glacial drift glacial groove glacier gland Glaser, Donald Arthur (1926 — 2013) Glashow, Sheldon (1932 ---RRB- glass GLAST (Gamma - ray Large Area Space Telescope) Glauber, Johann Rudolf (1607 — 1670) glaucoma glauconite Glenn, John Herschel, Jr. (1921 ---RRB- Glenn Research Center Glennan, T (homas) Keith (1905 — 1995) glenoid cavity glia glial cell glider Gliese 229B Gliese 581 Gliese 67 (HD 10307, HIP 7918) Gliese 710 (HD 168442, HIP 89825) Gliese 86 Gliese 876 Gliese Catalogue glioma glissette glitch Global Astrometric Interferometer for Astrophysics (GAIA) Global Oscillation Network Group (GONG) Globalstar globe Globigerina 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 glow - worm glucagon glucocorticoid glucose glucoside gluon Glushko, Valentin Petrovitch (1908 — 1989) glutamic acid glutamine gluten gluteus maximus glycerol glycine glycogen glycol glycolysis glycoprotein glycosidic bond glycosuria glyoxysome GMS (Geosynchronous Meteorological Satellite) GMT (Greenwich Mean Time) Gnathostomata gneiss Go Go, No - go goblet cell GOCE (Gravity field and steady - state Ocean Circulation Explorer) God Goddard, Robert Hutchings (1882 — 1945) Goddard Institute for Space Studies Goddard Space Flight Center Gödel, Kurt (1906 — 1978) Gödel universe Godwin, Francis (1562 — 1633) GOES (Geostationary Operational Environmental Satellite) goethite goiter gold Gold, Thomas (1920 — 2004) Goldbach conjecture golden ratio (phi) Goldin, Daniel Saul (1940 ---RRB- gold - leaf electroscope Goldstone Tracking Facility Golgi, Camillo (1844 — 1926) Golgi apparatus Golomb, Solomon W. (1932 — 2016) golygon GOMS (Geostationary Operational Meteorological Satellite) gonad gonadotrophin - releasing hormone gonadotrophins Gondwanaland Gonets goniatite goniometer gonorrhea Goodricke, John (1764 — 1786) googol Gordian Knot Gordon, Richard Francis, Jr. (1929 — 2017) Gore, John Ellard (1845 — 1910) gorge 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) Graaf, Regnier de (1641 — 1673) Graafian follicle GRAB graben GRACE (Gravity Recovery and Climate Experiment) graceful graph gradient Graham, Ronald (1935 ---RRB- Graham, Thomas (1805 — 1869) Graham's law of diffusion Graham's number GRAIL (Gravity Recovery and Interior Laboratory) grain (cereal) grain (unit) gram gram - atom Gramme, Zénobe Théophile (1826 — 1901) gramophone Gram's stain Gran Telescopio Canarias (GTC) Granat Grand Tour grand unified theory (GUT) Grandfather Paradox Granit, Ragnar Arthur (1900 — 1991) granite granulation granule granulocyte graph graph theory graphene graphite GRAPHS AND GRAPH THEORY graptolite grass grassland gravel graveyard orbit gravimeter gravimetric analysis Gravitational Biology Facility gravitational collapse gravitational constant (G) gravitational instability gravitational lens gravitational life gravitational lock gravitational microlensing GRAVITATIONAL PHYSICS gravitational slingshot effect gravitational waves graviton gravity gravity gradient gravity gradient stabilization Gravity Probe A Gravity Probe B gravity - assist gray (Gy) gray goo gray matter 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 greater omentum greatest elongation Green, George (1793 — 1841) Green, Nathaniel E. Green, Thomas Hill (1836 — 1882) 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, François Auguste Victor (1871 — 1935) Grignard reagent grike Grimaldi, Francesco Maria (1618 — 1663) Grissom, Virgil (1926 — 1967) grit gritstone Groom Lake Groombridge 34 Groombridge Catalogue gross ground, electrical ground state ground - track group group theory GROUPS AND GROUP THEORY growing season growth growth hormone growth hormone - releasing hormone growth plate 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 G - type asteroid Guericke, Otto von (1602 — 1686) guanine Guiana Space Centre guidance, inertial Guide Star Catalog (GSC) guided missile guided missiles, postwar development Guillaume, Charles Édouard (1861 — 1938) Gulf Stream (ocean current) Gulfstream (jet plane) Gullstrand, Allvar (1862 — 1930) gum Gum Nebula gun metal gunpowder Gurwin Gusev Crater gut Gutenberg, Johann (c. 1400 — 1468) Guy, Richard Kenneth (1916 ---RRB- guyot Guzman Prize gymnosperm gynecology gynoecium gypsum gyrocompass gyrofrequency gyropilot gyroscope gyrostabilizer Gyulbudagian's Nebula (Hgamma - ray satellites Gamow, George (1904 — 1968) ganglion gangrene Ganswindt, Hermann (1856 — 1934) Ganymede «garbage theory», of the origin of life Gardner, Martin (1914 — 2010) Garneau, Marc (1949 ---RRB- garnet Garnet Star (Mu Cephei) Garnet Star Nebula (IC 1396) garnierite Garriott, Owen K. (1930 ---RRB- Garuda gas gas chromatography gas constant gas giant gas laws gas - bounded nebula gaseous nebula gaseous propellant gaseous - propellant rocket engine gasoline Gaspra (minor planet 951) Gassendi, Pierre (1592 — 1655) gastric juice gastrin gastrocnemius gastroenteritis gastrointestinal tract gastropod gastrulation Gatewood, George D. (1940 ---RRB- Gauer - Henry reflex gauge boson gauge theory gauss (unit) Gauss, Carl Friedrich (1777 — 1855) Gaussian distribution Gay - Lussac, Joseph Louis (1778 — 1850) GCOM (Global Change Observing Mission) Geber (c. 720 — 815) gegenschein Geiger, Hans Wilhelm (1882 — 1945) Geiger - Müller counter Giessler tube gel gelatin Gelfond's theorem Gell - Mann, Murray (1929 ---RRB- GEM «gemination,» of martian canals Geminga Gemini (constellation) Gemini Observatory Gemini Project Gemini - Titan II gemstone gene gene expression gene mapping gene pool 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 code genetic counseling genetic disorder genetic drift genetic engineering genetic marker genetic material genetic pool genetic recombination genetics GENETICS AND HEREDITY Geneva Extrasolar Planet Search Program genome genome, interstellar transmission of genotype gentian violet genus geoboard geode geodesic geodesy geodesy satellites geodetic precession Geographos (minor planet 1620) geography GEOGRAPHY Geo - IK geologic time geology GEOLOGY AND PLANETARY SCIENCE geomagnetic field geomagnetic storm geometric mean geometric sequence geometry GEOMETRY geometry puzzles geophysics GEOS (Geodetic Earth Orbiting Satellite) Geosat geostationary orbit geosynchronous orbit geosynchronous / geostationary transfer orbit (GTO) geosyncline Geotail (satellite) geotropism germ germ cells Germain, Sophie (1776 — 1831) German Rocket Society germanium germination Gesner, Konrad von (1516 — 1565) gestation Get Off the Earth puzzle 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 ---RRB- Giacobini - Zinner, Comet (Comet 21P /) Giaever, Ivar (1929 ---RRB- giant branch Giant Magellan Telescope giant molecular cloud giant planet giant star Giant's Causeway Giauque, William Francis (1895 — 1982) gibberellins Gibbs, Josiah Willard (1839 — 1903) Gibbs free energy Gibson, Edward G. (1936 ---RRB- Gilbert, William (1544 — 1603) gilbert (unit) Gilbreath's conjecture gilding gill gill (unit) Gilruth, Robert R. (1913 — 2000) gilsonite gimbal Ginga ginkgo Giotto (ESA Halley probe) GIRD (Gruppa Isutcheniya Reaktivnovo Dvisheniya) girder glacial drift glacial groove glacier gland Glaser, Donald Arthur (1926 — 2013) Glashow, Sheldon (1932 ---RRB- glass GLAST (Gamma - ray Large Area Space Telescope) Glauber, Johann Rudolf (1607 — 1670) glaucoma glauconite Glenn, John Herschel, Jr. (1921 ---RRB- Glenn Research Center Glennan, T (homas) Keith (1905 — 1995) glenoid cavity glia glial cell glider Gliese 229B Gliese 581 Gliese 67 (HD 10307, HIP 7918) Gliese 710 (HD 168442, HIP 89825) Gliese 86 Gliese 876 Gliese Catalogue glioma glissette glitch Global Astrometric Interferometer for Astrophysics (GAIA) Global Oscillation Network Group (GONG) Globalstar globe Globigerina 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 glow - worm glucagon glucocorticoid glucose glucoside gluon Glushko, Valentin Petrovitch (1908 — 1989) glutamic acid glutamine gluten gluteus maximus glycerol glycine glycogen glycol glycolysis glycoprotein glycosidic bond glycosuria glyoxysome GMS (Geosynchronous Meteorological Satellite) GMT (Greenwich Mean Time) Gnathostomata gneiss Go Go, No - go goblet cell GOCE (Gravity field and steady - state Ocean Circulation Explorer) God Goddard, Robert Hutchings (1882 — 1945) Goddard Institute for Space Studies Goddard Space Flight Center Gödel, Kurt (1906 — 1978) Gödel universe Godwin, Francis (1562 — 1633) GOES (Geostationary Operational Environmental Satellite) goethite goiter gold Gold, Thomas (1920 — 2004) Goldbach conjecture golden ratio (phi) Goldin, Daniel Saul (1940 ---RRB- gold - leaf electroscope Goldstone Tracking Facility Golgi, Camillo (1844 — 1926) Golgi apparatus Golomb, Solomon W. (1932 — 2016) golygon GOMS (Geostationary Operational Meteorological Satellite) gonad gonadotrophin - releasing hormone gonadotrophins Gondwanaland Gonets goniatite goniometer gonorrhea Goodricke, John (1764 — 1786) googol Gordian Knot Gordon, Richard Francis, Jr. (1929 — 2017) Gore, John Ellard (1845 — 1910) gorge 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) Graaf, Regnier de (1641 — 1673) Graafian follicle GRAB graben GRACE (Gravity Recovery and Climate Experiment) graceful graph gradient Graham, Ronald (1935 ---RRB- Graham, Thomas (1805 — 1869) Graham's law of diffusion Graham's number GRAIL (Gravity Recovery and Interior Laboratory) grain (cereal) grain (unit) gram gram - atom Gramme, Zénobe Théophile (1826 — 1901) gramophone Gram's stain Gran Telescopio Canarias (GTC) Granat Grand Tour grand unified theory (GUT) Grandfather Paradox Granit, Ragnar Arthur (1900 — 1991) granite granulation granule granulocyte graph graph theory graphene graphite GRAPHS AND GRAPH THEORY graptolite grass grassland gravel graveyard orbit gravimeter gravimetric analysis Gravitational Biology Facility gravitational collapse gravitational constant (G) gravitational instability gravitational lens gravitational life gravitational lock gravitational microlensing GRAVITATIONAL PHYSICS gravitational slingshot effect gravitational waves graviton gravity gravity gradient gravity gradient stabilization Gravity Probe A Gravity Probe B gravity - assist gray (Gy) gray goo gray matter 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 greater omentum greatest elongation Green, George (1793 — 1841) Green, Nathaniel E. Green, Thomas Hill (1836 — 1882) 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, François Auguste Victor (1871 — 1935) Grignard reagent grike Grimaldi, Francesco Maria (1618 — 1663) Grissom, Virgil (1926 — 1967) grit gritstone Groom Lake Groombridge 34 Groombridge Catalogue gross ground, electrical ground state ground - track group group theory GROUPS AND GROUP THEORY growing season growth growth hormone growth hormone - releasing hormone growth plate 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 G - type asteroid Guericke, Otto von (1602 — 1686) guanine Guiana Space Centre guidance, inertial Guide Star Catalog (GSC) guided missile guided missiles, postwar development Guillaume, Charles Édouard (1861 — 1938) Gulf Stream (ocean current) Gulfstream (jet plane) Gullstrand, Allvar (1862 — 1930) gum Gum Nebula gun metal gunpowder Gurwin Gusev Crater gut Gutenberg, Johann (c. 1400 — 1468) Guy, Richard Kenneth (1916 ---RRB- guyot Guzman Prize gymnosperm gynecology gynoecium gypsum gyrocompass gyrofrequency gyropilot gyroscope gyrostabilizer Gyulbudagian's Nebula (HGamma - ray Large Area Space Telescope) Glauber, Johann Rudolf (1607 — 1670) glaucoma glauconite Glenn, John Herschel, Jr. (1921 ---RRB- Glenn Research Center Glennan, T (homas) Keith (1905 — 1995) glenoid cavity glia glial cell glider Gliese 229B Gliese 581 Gliese 67 (HD 10307, HIP 7918) Gliese 710 (HD 168442, HIP 89825) Gliese 86 Gliese 876 Gliese Catalogue glioma glissette glitch Global Astrometric Interferometer for Astrophysics (GAIA) Global Oscillation Network Group (GONG) Globalstar globe Globigerina 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 glow - worm glucagon glucocorticoid glucose glucoside gluon Glushko, Valentin Petrovitch (1908 — 1989) glutamic acid glutamine gluten gluteus maximus glycerol glycine glycogen glycol glycolysis glycoprotein glycosidic bond glycosuria glyoxysome GMS (Geosynchronous Meteorological Satellite) GMT (Greenwich Mean Time) Gnathostomata gneiss Go Go, No - go goblet cell GOCE (Gravity field and steady - state Ocean Circulation Explorer) God Goddard, Robert Hutchings (1882 — 1945) Goddard Institute for Space Studies Goddard Space Flight Center Gödel, Kurt (1906 — 1978) Gödel universe Godwin, Francis (1562 — 1633) GOES (Geostationary Operational Environmental Satellite) goethite goiter gold Gold, Thomas (1920 — 2004) Goldbach conjecture golden ratio (phi) Goldin, Daniel Saul (1940 ---RRB- gold - leaf electroscope Goldstone Tracking Facility Golgi, Camillo (1844 — 1926) Golgi apparatus Golomb, Solomon W. (1932 — 2016) golygon GOMS (Geostationary Operational Meteorological Satellite) gonad gonadotrophin - releasing hormone gonadotrophins Gondwanaland Gonets goniatite goniometer gonorrhea Goodricke, John (1764 — 1786) googol Gordian Knot Gordon, Richard Francis, Jr. (1929 — 2017) Gore, John Ellard (1845 — 1910) gorge 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) Graaf, Regnier de (1641 — 1673) Graafian follicle GRAB graben GRACE (Gravity Recovery and Climate Experiment) graceful graph gradient Graham, Ronald (1935 ---RRB- Graham, Thomas (1805 — 1869) Graham's law of diffusion Graham's number GRAIL (Gravity Recovery and Interior Laboratory) grain (cereal) grain (unit) gram gram - atom Gramme, Zénobe Théophile (1826 — 1901) gramophone Gram's stain Gran Telescopio Canarias (GTC) Granat Grand Tour grand unified theory (GUT) Grandfather Paradox Granit, Ragnar Arthur (1900 — 1991) granite granulation granule granulocyte graph graph theory graphene graphite GRAPHS AND GRAPH THEORY graptolite grass grassland gravel graveyard orbit gravimeter gravimetric analysis Gravitational Biology Facility gravitational collapse gravitational constant (G) gravitational instability gravitational lens gravitational life gravitational lock gravitational microlensing GRAVITATIONAL PHYSICS gravitational slingshot effect gravitational waves graviton gravity gravity gradient gravity gradient stabilization Gravity Probe A Gravity Probe B gravity - assist gray (Gy) gray goo gray matter 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 greater omentum greatest elongation Green, George (1793 — 1841) Green, Nathaniel E. Green, Thomas Hill (1836 — 1882) 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, François Auguste Victor (1871 — 1935) Grignard reagent grike Grimaldi, Francesco Maria (1618 — 1663) Grissom, Virgil (1926 — 1967) grit gritstone Groom Lake Groombridge 34 Groombridge Catalogue gross ground, electrical ground state ground - track group group theory GROUPS AND GROUP THEORY growing season growth growth hormone growth hormone - releasing hormone growth plate 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 G - type asteroid Guericke, Otto von (1602 — 1686) guanine Guiana Space Centre guidance, inertial Guide Star Catalog (GSC) guided missile guided missiles, postwar development Guillaume, Charles Édouard (1861 — 1938) Gulf Stream (ocean current) Gulfstream (jet plane) Gullstrand, Allvar (1862 — 1930) gum Gum Nebula gun metal gunpowder Gurwin Gusev Crater gut Gutenberg, Johann (c. 1400 — 1468) Guy, Richard Kenneth (1916 ---RRB- guyot Guzman Prize gymnosperm gynecology gynoecium gypsum gyrocompass gyrofrequency gyropilot gyroscope gyrostabilizer Gyulbudagian's Nebula (HH215)