Related by context. Frequent words. (Click for all words.) 75 rocky planets 74 planets 71 planets orbiting 70 extrasolar planets 69 exoplanets 67 brown dwarfs 66 exoplanet 63 habitable zone 63 quasars 62 Milky Way galaxy 61 supernovae 61 galaxies 60 nebulae 60 planetary 60 distant galaxies 59 dwarf galaxies 59 distant galaxy 59 asteroids 59 galaxy 59 brown dwarf 59 supernovas 59 planet orbiting 59 Alpha Centauri 58 comets 57 Enceladus 57 pulsars 57 Solar System 57 celestial bodies 56 astrophysical 56 gamma ray burst 56 supermassive black holes 56 gravitational waves 56 Kuiper Belt 56 galaxy clusters 56 Earths 55 Gliese 55 gamma ray bursts 55 supernova 55 Astronomers 55 astronomers 55 celestial objects 55 Milky Way 55 asteroid 54 neutron stars 54 supermassive black hole 54 organic molecules 54 quasar 54 Sedna 54 Saturn moon 54 interstellar dust 53 planet 53 XMM Newton 53 nebula 53 neutron star 53 redshift 53 Betelgeuse 53 meteorites 53 comet 52 astrobiology 52 neutrino 52 hydrothermal vents 52 Saturn rings 52 astrophysicists 52 extraterrestrial 51 orbits 51 moons 51 abundances 51 pulsar 51 sunspots 51 infrared wavelengths 51 magnetosphere 50 Higgs boson 50 solar flares 50 Spitzer Space Telescope 50 cosmologists 50 universe 50 constellations 50 asteroid belt 50 NEOs 50 planetary scientist 50 cosmic rays 50 spiral galaxy 50 galactic 49 interstellar space 49 astronomer 49 Meridiani Planum 49 aurora 49 cosmos 49 auroras 49 fainter 49 meteor showers 49 meteors 49 orbiting 49 Mars 49 habitability 48 interstellar medium 48 antimatter 48 GLAST 48 X ray Observatory 48 habitable 48 Uranus