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(Click for frequent words.) 81 asteroids 74 comet 71 Apophis 67 meteoroid 67 Asteroid 66 Apophis asteroid 66 comets 66 RQ# 65 meteor 65 Earth asteroids 63 impactor 63 planetoid 63 meteoroids 63 comet nucleus 62 Kuiper Belt object 62 NEAs 62 Pluto Charon 61 gaseous planet 61 Itokawa 61 protoplanet 61 planets 61 meteorite 61 # Apophis 61 asteroid Itokawa 61 impactors 61 asteroid impacts 60 MN4 60 orbiting 60 YU# 60 spacecraft 60 celestial object 60 QQ# 60 cosmic collisions 60 asteroid Apophis 59 GJ#b 59 protoplanets 59 Nasa spacecraft 59 Gliese #c 59 WASP #b 59 meteorites 59 exoplanet 59 solar flares 59 Spaceguard Survey 59 extrasolar planet 59 Comet Tempel 1 59 asteroidal 59 Corot 7b 59 supernova explosion 58 Saturn moon 58 Toutatis 58 Churyumov Gerasimenko 58 rocky planets 58 asteroid belt 58 Kuiper belt object 58 distant galaxy 58 Epsilon Eridani 58 #P/Churyumov-Gerasimenko 58 cometary 58 lunar surface 58 Halley comet 58 NEOs 57 impactor spacecraft 57 Chicxulub 57 micrometeoroids 57 comet dust 57 WD5 57 asteroid collisions 57 extrasolar planets 57 Galileo spacecraft 57 Kepler #b 57 ejecta 57 extrasolar 57 orbits 57 icy moons 57 unmanned spacecraft 57 Martian rovers 57 planet Uranus 57 moons orbiting 57 TrES 4 57 flyby spacecraft 57 moon Charon 57 exoplanets orbiting 57 Earthlike planet 56 Oort Cloud 56 comets asteroids 56 Andromeda galaxy 56 orbital debris 56 galactic clusters 56 Cassini 56 Upsilon Andromedae b 56 Saturn rings 56 exoplanetary 56 Earthlike planets 56 GRB #B 56 Halley Comet 56 moonlets 56 gamma ray burst 56 Comet Hartley 2 56 planets orbiting 56 asteroids comets 56 Kuiper Belt Object 56 Mars 56 martian atmosphere 55 icy comets 55 cosmic ray 55 Martian surface 55 Comet Hartley 55 exoplanets 55 colliding asteroids 55 Jenniskens 55 Comet Halley 55 Gliese #g 55 astronomers 55 Gerard Kuiper 55 Martian crater 55 Oort cloud 55 robotic spacecraft 55 galaxy 55 moonlet 55 interstellar 55 infrared telescope 55 asteroid Steins 55 asteroids orbiting 55 extraterrestrial 55 Deep Impact probe 55 Tempel 1 55 planet orbiting 55 planetesimals 55 GJ #b [001] 55 coronal mass ejection 55 habitable planets 55 Kuiper Belt Objects 55 asteroid Vesta 55 Kuiper belt 55 comet particles 55 Gliese #d 55 outer planets 55 Mandushev 55 transiting planet 55 Saturnian moon 55 Comet #P/Churyumov-Gerasimenko 55 magnetar 55 Kuiper Belt objects 54 orbiter 54 cometary debris 54 HD#b 54 Deep Impact comet 54 Earth Object 54 merging galaxies 54 NASA Stardust spacecraft 54 neutron star 54 planet WASP #b 54 Red Planet 54 comet Tempel 1 54 New Horizons spacecraft 54 Upsilon Andromedae 54 gravitational keyhole 54 KBOs 54 Sojourner rover 54 interstellar dust grains 54 CoRoT 7b 54 Saturn moons 54 Shoemaker Levy 54 terrestrial planets 54 Cassini Huygens spacecraft 54 Mars Odyssey spacecraft 54 Chicxulub crater 54 Tunguska meteorite 54 P/# A2 54 Tunguska object 54 Stardust spacecraft 54 dwarf planet 54 Martian atmosphere 54 cosmic cannibal 54 Cassini Huygens 54 super Earths 53 comet Churyumov Gerasimenko 53 NASA Voyager spacecraft 53 NASA Kepler 53 planetoids 53 Opportunity rover 53 orbiting spacecraft 53 Antennae Galaxies 53 comets orbiting 53 Comet Shoemaker Levy 53 galaxy cluster 53 trans Neptunian objects 53 NASA Cassini spacecraft 53 Eta Carinae 53 X ray observatory 53 Fomalhaut b 53 Milky Way Galaxy 53 comet #P/Churyumov-Gerasimenko 53 GJ #b [002] 53 smallest exoplanet 53 Earth 53 Voyager spacecraft 53 inhabitable planets 53 APXS 53 Messenger spacecraft 53 planets orbits 53 globular clusters 53 neutrino 53 planemos 53 Earth objects NEOs 53 Nibiru 53 moons Phobos 53 Baptistina 53 Kuiper belt objects 53 retrograde orbit 53 Wolszczan 53 Quaoar 53 gravitational slingshot 53 robotic explorer 53 Beta Pictoris 53 Saturnian moons 53 planetary 53 Sensing Satellite LCROSS 53 OSIRIS REx 53 HL Tau 53 globular cluster 53 comet Shoemaker Levy 53 galaxy M# [002] 53 bolide 53 Comet Churyumov Gerasimenko 53 galaxy M# [001] 53 elliptical galaxy 53 SIM PlanetQuest 52 Swift Tuttle 52 interstellar dust 52 Comet 9P/Tempel 1 52 Sedna 52 Viking Lander 52 interplanetary 52 Comet Boethin 52 Galaxy Evolution 52 detect gravitational waves 52 transiting exoplanet 52 gravitational waves 52 Kepler 9c 52 moon 52 binary asteroid 52 planet magnetosphere 52 spacecraft Cassini 52 Asteroids 52 supernova 52 planets orbiting sun 52 LCROSS 52 millisecond pulsar 52 comet tail 52 exo planets 52 Cassini spacecraft 52 Itokawa asteroid 52 exo planet 52 dwarf galaxies 52 Kuiper Belt 52 Tunguska asteroid 52 Asteroid Itokawa 52 NASA Kepler spacecraft 52 Mars moon Phobos 52 supernovas 52 Triangulum 52 Saturn Cassini 52 lunar crater 52 dwarf galaxy 52 Deep Impact craft 52 HD #b [001] 52 comet Wild 52 Mars Reconnaissance Orbiter MRO 52 Ring Nebula 52 robotic rovers 52 COROT exo 3b 52 habitable planet 52 orbit 52 innermost planet 52 Earth radii 52 Comet Lulin 52 interstellar particles 52 gravitationally bound 52 Pluto 52 HD #b [002] 52 highly elliptical orbits 52 infalling 52 Pluto Eris 52 Milky Way galaxy 52 radial velocity 52 lander 52 satellites orbiting Earth 52 GRB # 52 transiting planets 52 BP Psc 52 COROT 52 Epsilon Aurigae 52 star Gliese 52 Goldilocks planet 52 cosmic rays 52 Late Heavy Bombardment 52 meteors 52 distant quasar 52 Hayabusa spacecraft 52 hypervelocity stars 52 CoRoT 52 moon Io 52 Andromeda Galaxy 52 planets orbiting distant 52 extrasolar planetary 52 galaxies 52 SN #gy 52 gravitational microlensing 52 Lunar Prospector 52 microlensing 51 Jovian moon 51 Fermi telescope 51 Shackleton crater 51 orbiting observatory 51 infrared observatory 51 subatomic particle 51 comet McNaught 51 Saturn outermost moon 51 Phobos 51 carbonaceous chondrite 51 inner asteroid belt 51 jovian 51 LCROSS spacecraft 51 NASA rovers 51 unmanned probes 51 rover Opportunity 51 VD# [001] 51 planet HD #b 51 elliptical orbit 51 moon Titan 51 periodic dimming 51 orbiting telescope 51 brown dwarf 51 inner moons 51 martian 51 spaceship 51 NASA MESSENGER spacecraft 51 Haumea 51 cometary dust 51 accretion disk 51 Jay Melosh 51 elongated orbits 51 Murchison meteorite 51 moons 51 WISE spacecraft 51 closest flyby 51 Beta Pictoris b 51 phyllosilicates 51 extrasolar planetary systems 51 Martian equator 51 Stardust capsule 51 airbursts 51 Cancri e 51 Ulysses spacecraft 51 galactic disk 51 planets circling 51 Supernova #A 51 Martian 51 neutralinos 51 Jupiter icy moons 51 distant galaxies 51 moon Phobos 51 stellar occultation 51 lunar orbiter 51 magnetosphere 51 nebular 51 Evolution Explorer 51 exosolar planets 51 comets meteors 51 dimming starlight 51 moon Enceladus 51 Spaceguard 51 galactic cosmic rays 51 elongated orbit 51 Jupiter moon Io 51 BLG #Lb 51 constellation Cassiopeia 51 Martian dust 51 GRBs 51 colliding galaxies 51 celestial bodies 51 EPOXI spacecraft 51 X ray binary 51 Zeta Ophiuchi 51 Solar System 51 Martian rover 51 moon Deimos 51 Saturnian 51 AU Mic 51 gravitationally 50 Lunar Reconnaissance Orbiter LRO 50 GQ Lupi 50 Enceladus 50 interstellar distances 50 galactic 50 Centaur rocket 50 polar orbit 50 galaxy clusters 50 asteroid Eros 50 Orbiter LRO 50 Lutetia 50 ejecta blanket 50 Alpha Centauri 50 Tunguska Siberia 50 planet Gliese #g 50 Cassini flyby 50 Jovian moons 50 Huygens descent 50 flyby 50 GALEX 50 WISE telescope 50 irregularly shaped asteroid 50 cosmic microwave radiation 50 spacecrafts 50 martian surface 50 meteorite impacts 50 Hubble telescope 50 orbiting Hubble Space Telescope 50 exosphere 50 habitable worlds 50 Kepler spacecraft 50 BepiColombo 50 heavily cratered 50 Chicxulub Crater 50 quasar 50 spacecraft flyby 50 Trojan asteroids 50 lunar perigee 50 distant supernovae 50 Terrestrial Planet Finder 50 Earthlike 50 gamma ray bursts 50 strangelets 50 Earth Asteroid 50 Yarkovsky effect 50 Fomalhaut 50 Deep Impact 50 perihelion 50 Earth magnetosphere 50 Martian rocks 50 Virgo Cluster 50 Saturn moon Enceladus 50 planet orbits 50 planet 50 NASA LCROSS 50 MESSENGER 50 Rosetta spacecraft 50 KT extinction 50 Wolf Rayet star 50 craters 50 NASAs 50 superstorm 50 Apollo missions 50 orbital velocity 50 Pegasi 50 magnetars 50 supernova explosions 50 Exoplanet 50 Galilean moons 50 Deep Impact spacecraft 50 comet Tempel Tuttle 50 Martian soil 50 Earth orbit 50 dinosaur extinction 50 Cabeus 50 Rosetta lander 50 outer space 50 micrometeorite 50 GA6 50 Martian lander 50 Asteroid Belt 50 asteroid Lutetia 50 Voyager probes 50 galactic alignment 49 Earth asteroid Itokawa 49 interstellar dust samples 49 exoplanet hunter 49 Orion Nebula 49 asteroid hurtling 49 microquasar 49 extrasolar planets orbiting 49 navigate autonomously 49 sunlike stars 49 Gravitational waves 49 NASA Kepler telescope 49 retrograde orbits 49 lunar crust 49 ESA Rosetta 49 orbited Jupiter 49 Titan flyby 49 galaxies collide 49 Timothy Spahr 49 crater 49 sunlike star 49 Gamma ray burst 49 Cabeus crater 49 planetary astronomy 49 orbital resonance 49 extraterrestrial civilization 49 brown dwarfs 49 quasars 49 extragalactic 49 Higgs boson particle 49 eclipsing binary 49 NASA rovers Spirit 49 neighboring Andromeda galaxy 49 red supergiant 49 Higgs bosons 49 planet TrES 49 Comet Hale Bopp 49 earthlike planets 49 geomagnetic storms 49 Higgs particle 49 astrobiological 49 Epimetheus 49 olivine mineral 49 elliptical orbits 49 spherules 49 pulsar 49 MESSENGER spacecraft 49 interstellar dust particles 49 Mimas 49 AGNs 49 twin Voyager spacecraft 49 Hubble Space Telescope 49 X ray telescopes 49 gamma rays 49 rover 49 antihelium 49 ultraluminous galaxy 49 Orionid 49 mu Arae 49 copper impactor 49 Phobos Grunt 49 manned lunar mission 49 KT boundary 49 tiny meteoroids 49 Hot Jupiters 49 moon Mab 49 meteoritic material 49 Omega Centauri 49 gravitational interactions 49 brightest supernova 49 Comet Machholz 49 OGLE TR 49 moon Europa 49 Sasselov 49 hypervelocity 49 unmanned rover 49 moonquakes 49 SIRTF 49 planetary nebulae 49 G#.# +#.# 49 Gliese #e 49 hypervelocity star 49 plutoid 49 stony meteorite 49 HIP #b 49 comet Hartley 2 49 quark gluon plasma 49 ringed planet 49 Explorer WISE 49 IBEX spacecraft 49 extraterrestrial civilizations 49 meteor impacts 49 cosmic radiation 49 asteroid Ceres 49 subsurface ocean 49 NASA Cassini 49 spacecraft orbiting 49 Astronomers 49 CoRoT #b 49 Orbiter MRO 49 Earths 49 galaxy NGC 49 supermassive black hole 49 volcanic eruptions 49 MUSES C 49 Bullet Cluster 49 gravitational wave 49 Saturnian moon Titan 49 Pan STARRS 49 spacecraft Hayabusa 49 interplanetary dust 49 circumstellar disk 49 Astrophysicists 49 onrushing comet 49 rover Sojourner 49 orbiting Cassini spacecraft 49 antiproton 49 planetary nebula 49 constellation Carina 49 Boethin 49 planetary embryos 48 substorm 48 Large Magellanic Cloud 48 Gusev crater 48 observable universe 48 solar corona 48 Avishay Gal Yam 48 NASA twin rovers 48 NASA EPOXI mission 48 Giovanni Cassini 48 Cometary 48 cosmic 48 Hayabusa capsule 48 strangelet 48 astrophysical objects 48 Neukum 48 protoplanetary disk 48 meteor shower 48 microlensing events 48 EPOXI mission 48 Ranging spacecraft 48 proto planetary disk 48 orbiting planets 48 HiRISE image 48 Bonneville Crater 48 Mars Reconnaissance Orbiter 48 planetary astronomer 48 constellation Virgo 48 dust devils 48 ExoMars rover 48 Comet Elenin 48 gamma ray observatory 48 Hubble 48 NASA Lunar Prospector 48 Earth magnetotail 48 TU# [002] 48 asteroid orbit 48 Jupiter moons 48 albedo reflectivity 48 Hubble Telescope 48 coronal mass ejections 48 planet gravitational tug 48 ESA Mars 48 meteoroid impacts 48 COROT 7b 48 comet chaser 48 orbiting Hubble telescope 48 spiral galaxy NGC 48 NASA Opportunity rover 48 Huygens spacecraft 48 Reconnaissance Orbiter 48 Iapetus 48 lunar equator 48 NASA Lunar Reconnaissance 48 PSR J# 48 Planck satellite 48 alien spaceship 48 supernovae 48 Venus Climate Orbiter 48 SN #C 48 radial velocity method 48 Mars rover 48 Mini Thermal Emission 48 Huygens 48 protostar 48 energetic cosmic rays 48 millisecond pulsars 48 Yinghuo 1 48 Venusian atmosphere 48 Andromeda 48 spacecraft thrusters 48 Samuel Oschin Telescope 48 eclipsing binaries 48 Orionids 48 Tunguska 48 boson 48 olivine 48 telescope 48 atomic nucleus 48 XMM Newton 48 interstellar space 48 NASA rover Opportunity 48 substorms 48 Isidis Planitia 48 antimatter particles 48 cometary material 48 MIT planetary scientist 48 orbiting Mars 48 cosmological distances 48 magma ocean 48 TW Hydrae 48 comet Lulin 48 interstellar grains 48 shepherding spacecraft 48 Jupiter magnetosphere 48 neutron stars 48 sized planets orbiting 48 pyroclastic flow 48 astronomer 48 constellation Sagittarius 48 Galilean satellites 48 HIRES spectrometer 48 lunar meteorites 48 Keck Interferometer 48 Maria Zuber 48 X ray telescope 48 permanently shadowed crater 48 Cosmic rays 48 comet flyby 48 CoRoT 9b 48 LORRI 48 Meteorites 48 noctilucent clouds 48 regolith 48 stellar occultations 48 Milky Way 48 heliopause 48 telescopes astronomers 48 astrophysicists 48 Mojzsis 48 circular orbits 48 micrometeoroid 48 planets orbiting stars 48 planetary Transits 48 magnetic reconnection 48 carbonate minerals 48 radial velocity technique 48 Mars Pathfinder 48 circumstellar 48 Korotev 48 telescopic observations 48 plutoids 48 Einstein relativity theory 48 interplanetary spacecraft 48 asteroid collides 48 crewed spacecraft 48 micrometeorites 48 Saturn moon Mimas 48 highly elliptical orbit 48 orbiting observatories 48 polar vortex 48 sulfur isotope 48 constellation Hercules 48 Ranging MESSENGER spacecraft 48 Deep Impact flyby spacecraft 48 chondrites 47 prebiotic molecules 47 NASA rover Spirit 47 globulars 47 galaxy formation 47 moon Ganymede 47 occultations 47 probe Huygens 47 Martian meteorites 47 AB Aurigae 47 neutrinos 47 giant elliptical galaxy 47 WIMPs 47 Victoria Crater 47 intrinsic brightness 47 Tempel Tuttle 47 thermal emission spectrometer 47 sun corona 47 Earth Asteroid Rendezvous 47 astrophysical 47 Flyby spacecraft 47 SN #A 47 asteroid flyby 47 Betelgeuse 47 Bottke 47 inner Oort Cloud 47 infrared telescopes 47 orbiting Kepler telescope 47 type Ia supernova 47 gravitational lenses 47 super perigee moon 47 planet transits 47 NASA Spirit rover 47 UB# [003] 47 Hubble observations 47 Jupiter Ganymede 47 rover Spirit 47 Nili Fossae 47 Viking landers 47 Gliese 47 astronomer Clyde Tombaugh 47 hydrostatic equilibrium 47 nucleosynthesis 47 Schwarzschild radius 47 Von Frese 47 Opportunity Mars rover 47 Mars CRISM 47 planet Gliese #c 47 Sagittarius dwarf galaxy 47 transiting exoplanets 47 distant quasars 47 reionization 47 solar nebula 47 volcanic plumes 47 NASA Deep Impact 47 Meteor Crater 47 Mercury flyby 47 CoRoT satellite 47 nanosatellite 47 fainter objects 47 J# +# [002] 47 Martian terrain 47 exoplanet orbiting 47 Type Ia supernova 47 Makemake 47 Martian plains 47 Hesperian Epoch 47 smallest extrasolar planet 47 Titan Saturn 47 Bruce Jakosky 47 DIXI 47 atomic particles 47 starburst galaxies 47 ALH# 47 Mars northern latitudes 47 YORP effect 47 Solar TErrestrial RElations Observatory 47 accretion disks 47 Geminids 47 Methone 47 supervolcanoes 47 CMEs 47 Caloris Basin 47 lunar soil 47 cometary impacts 47 planetesimal 47 cosmic ray collisions 47 HiRISE camera 47 Hayabusa 47 Impact Probe MIP 47 potentially habitable planets 47 type Ia supernovae 47 robot rovers 47 EPOXI 47 Olympus Mons 47 Tunguska Event 47 Deep Impact mission 47 hot Jupiters 47 Comet Holmes 47 antiparticle 47 planets moons 47 Lulin Observatory 47 S/# P2 47 manned lunar 47 Ordovician extinction 47 Earth ionosphere 47 rock outcrop 47 Spitzer Space Telescope 47 neutrino particles 47 Stardust NExT 47 RX J# 47 moon Mimas 47 distant galaxy clusters 47 Chicxulub impact 47 Mars rovers Spirit 47 lunar regolith 47 Eridani 47 SOHO spacecraft 47 Drygalski ice tongue 47 comet Hale Bopp 47 BP Piscium 47 Sensing Satellite 47 particle 47 Grammier 47 LCROSS mission 47 Jupiter flyby 47 Earth orbiting satellites 47 Hubble Space Telescope HST 47 Hanny Voorwerp 47 proplyds 47 Voorwerp 47 TrES 47 Type Ia supernovas 47 aperture telescope 47 Henize #-# 47 red supergiants 47 eccentric orbits 47 Epoxi 47 micro meteorites 47 OGLE 47 robotic lander 47 Kepler Mission 47 spacetime 47 whiz harmlessly 47 Venusian surface 47 Kepler Space Telescope 47 baryon 47 outermost planets 47 Neutron stars 47 Sumatran earthquake 47 X ray emission 47 lunar 47 Manned missions 47 comet 9P/Tempel 47 planetary surfaces 47 TNOs 47 meson 47 RHESSI 47 supersymmetric particles 47 Mars rover Opportunity 47 Carina constellation 46 Saturnian system 46 OGLE TR #b 46 simulated lunar 46 ESA XMM Newton 46 Astrophysical 46 RS Ophiuchi 46 reentry capsule 46 Herschel Space 46 Valles Marineris 46 muon 46 Borealis basin 46 Scheila 46 sterile neutrino 46 Aqua satellite 46 Phoebe orbits 46 Super Earths 46 largest moon Charon 46 nicknamed Xena 46 Jupiter gravitational pull 46 tiny meteoroid 46 active volcanism 46 Nasa Deep Impact 46 heliosphere 46 Arches Cluster 46 moon permanently shadowed 46 Mars Lander 46 HD# [002] 46 permanently shadowed craters 46 LADEE 46 Proxima Centauri 46 Bug Nebula 46 Erik Asphaug 46 ray Space Telescope 46 coronal loops 46 icy moon Enceladus 46 ESA Huygens probe 46 lunar dust 46 Hipparcos 46 supernova remnant 46 Permian Triassic extinction 46 perigee 46 metallicity 46 comet Boethin 46 orbital rendezvous 46 isostatic rebound 46 Laser Interferometer Gravitational Wave 46 Orbiting Carbon Observatory 46 Japan Hayabusa spacecraft 46 supermassive 46 Keck telescope 46 circumstellar disks 46 aurorae 46 planetary orbits 46 Hayabusa probe 46 undersea volcanoes 46 alien civilizations 46 Cumbre Vieja 46 lander rover 46 Lake Cheko 46 spiral galaxy 46 Lunar CRater Observation 46 STEREO spacecraft 46 Impactor 46 proto galaxies 46 orbits Saturn 46 Microlensing 46 HiRISE camera aboard 46 magnetic monopoles 46 telescope atop Mauna 46 geoneutrinos 46 Lunar Crater Observation 46 Venusian 46 GeV 46 swingby 46 exoplanets planets 46 Earths orbiting 46 star Proxima Centauri 46 Chodas 46 gravitational interaction 46 Encke gap 46 comet orbit 46 infall 46 geomagnetic storm 46 interstellar cloud 46 Convection Rotation 46 pulsars 46 carbonaceous chondrites 46 geostationary orbits 46 Permian extinction 46 Boslough 46 astrometry 46 lander Beagle 2 46 Meridiani plains 46 protoplanetary 46 alien spacecraft 46 Meridiani Planum 46 cosmic dust 46 Syrtis Major 46 orbiting Saturn