Related by context. Frequent words. (Click for all words.) 84 exoplanets 75 planets 75 planets orbiting 75 exoplanet 71 rocky planets 70 brown dwarfs 67 astronomers 66 quasars 66 supernovae 66 pulsars 66 brown dwarf 65 Milky Way galaxy 65 distant galaxies 65 galaxies 64 Sedna 64 gamma ray bursts 64 comets 63 quasar 62 galaxy clusters 62 Milky Way 61 Saturn rings 61 Spitzer Space Telescope 61 infrared wavelengths 61 Astronomers 61 asteroids 60 gamma ray burst 60 supernovas 60 pulsar 60 supernova 60 gravitational waves 60 astrophysicists 60 galaxy 59 Solar System 59 redshift 59 neutron star 59 Kuiper Belt 59 celestial bodies 59 Gliese 58 celestial objects 58 neutrino 58 moons 58 Enceladus 58 comet 58 planetary 57 neutron stars 57 asteroid 57 nebula 57 habitable zone 56 neutrinos 56 supermassive black hole 56 spectroscopic 56 Kepler 56 telescopes 56 supermassive black holes 55 Saturn moon 55 orbits 55 Martian surface 54 sunspots 54 cosmic rays 54 astronomer 54 fainter 54 meteorites 54 magnetosphere 54 orbiting 53 infrared radiation 53 cosmic microwave background 53 organic molecules 53 astrobiology 53 Cassini 53 Red Planet 52 adaptive optics 52 telescope 52 Earths 52 Pluto 51 Astrophysical Journal 51 auroras 51 Higgs boson 51 planet 51 aurora 51 Cassini spacecraft 51 solar flares 51 spectrometers 51 polar regions 51 infrared 51 martian 51 spectroscopy 50 MESSENGER 50 subatomic particles 50 Pleiades 50 general relativity 50 sunspot 50 Mars Reconnaissance Orbiter 50 gamma rays 50 amateur astronomers 50 asteroid belt 50 Uranus 50 gamma ray 50 planetary scientist 50 Mars 49 moon Titan 49 spectra