Related by context. Frequent words. (Click for all words.) 76 rocky planets 71 planets 71 extrasolar planets 70 terrestrial planets 70 planets orbiting 68 extrasolar planet 67 exoplanets 66 brown dwarfs 66 exoplanet 65 Saturn moons 64 dwarf galaxies 64 globular clusters 64 distant galaxies 64 Milky Way galaxy 64 supernovae 63 planet orbiting 63 galaxies 63 HD #b [002] 63 Earth asteroids 63 Milky Way Galaxy 61 distant galaxy 61 astronomers 61 elliptical galaxies 61 Saturn moon 61 Saturn rings 60 asteroids 60 nebulae 60 brown dwarf 60 gravitational waves 60 Spitzer Space Telescope 60 outer planets 60 galaxy clusters 60 comets 59 quasars 59 XMM Newton 59 Solar System 59 supermassive black holes 59 Astronomers 59 supernovas 58 celestial objects 58 galaxy 58 supernova explosion 58 astrophysicists 57 pulsars 57 celestial bodies 57 gamma ray bursts 57 neutron stars 57 moons 57 gamma ray burst 57 organic molecules 57 Milky Way 57 astrophysical 57 comet 57 galaxy cluster 56 infrared wavelengths 56 quasar 56 optical telescopes 56 asteroid 56 unaided eye 56 habitable zone 56 cosmic microwave background 55 Betelgeuse 55 Gliese 55 Enceladus 55 orbits 55 planetary 55 telescopes 55 moon Titan 55 Sedna 55 NASA Cassini spacecraft 55 Martian surface 55 neutrino 55 Earths 54 pulsar 54 supernova 54 neutron star 54 interstellar dust 54 cometary 54 cosmologists 54 WM Keck Observatory 54 Alpha Centauri 54 spiral galaxies 54 Planck 54 sunspots 53 Red Planet 53 fainter 53 spectroscopic 53 Martian soil 53 abundances 53 Kuiper Belt 52 nebula 52 Mars 52 constellations 52 WMAP 52 asteroid belt 52 ringed planet 52 Hubble Telescope 52 planet 52 supermassive black hole 52 NASA Chandra 52 telescope