Related by context. Frequent words. (Click for all words.) 79 rocky planets 72 planets 70 brown dwarfs 69 planets orbiting 68 dwarf galaxies 65 organic molecules 65 galaxies 64 exoplanets 64 supernovae 64 quasars 64 brown dwarf 64 Solar System 64 extrasolar planets 64 planet orbiting 63 exoplanet 62 Milky Way galaxy 62 comets 62 galaxy clusters 62 supermassive black holes 61 asteroid belt 61 neutron stars 61 Kuiper Belt 61 habitable zone 61 nebulae 60 neutron star 59 asteroids 59 distant galaxies 59 supernovas 58 galaxy 58 pulsars 58 magnetosphere 58 Enceladus 58 quasar 57 neutrino 56 orbits 56 nuclei 56 planetary 56 supermassive black hole 56 astrophysical 56 Milky Way 56 gravitational waves 55 Spitzer Space Telescope 55 heliosphere 55 pulsar 55 Saturn rings 55 distant galaxy 55 redshift 55 volcanism 54 Alpha Centauri 54 infrared wavelengths 54 supernova 54 gamma ray bursts 54 nebula 54 asteroid 54 astronomers 54 Sedna 53 meteorites 53 hydrogen atoms 53 spiral galaxy 53 magnetic fields 53 Earths 53 interstellar space 53 abundances 53 atoms 53 comet 52 Betelgeuse 52 Iapetus 52 gamma ray burst 52 celestial bodies 52 spectroscopic 52 neutrinos 52 Astronomers 52 Galaxies 51 cosmic microwave background 51 Gliese 51 organic compounds 51 hematite 51 cosmic rays 51 Saturn moon 51 buckyballs 51 hydrothermal vents 51 moons 51 Uranus 51 XMM Newton 51 orbiting 51 planetary scientist 50 CMEs 50 convective 50 positrons 49 atomic particles 49 perturbations 49 molecules 49 dynamical 49 celestial objects 49 hydroxyl 49 Martian surface 49 cosmologists 49 moon Titan 49 X ray Observatory 49 hydrothermal 49 cosmological