Related by context. Frequent words. (Click for all words.) 80 Milky Way galaxy 77 galaxies 73 galaxy 73 distant galaxies 73 nebula 66 supermassive black holes 66 planets 66 neutron star 66 quasars 65 quasar 65 supernovae 64 Solar System 63 supernova 62 neutron stars 62 extrasolar planets 61 Saturn rings 61 pulsar 60 exoplanets 60 Galaxies 60 brown dwarf 60 comets 59 astronomers 59 galactic 58 Enceladus 57 pulsars 57 comet 57 exoplanet 57 gamma ray bursts 56 Kuiper Belt 56 Andromeda 55 Pleiades 55 cosmos 55 Astronomers 54 moons 54 celestial bodies 54 asteroid belt 54 atoms 54 gamma rays 53 fainter 53 neutrinos 53 astrophysicists 53 magnetic fields 53 subatomic particles 53 universe 53 starlight 52 suns 52 nuclei 52 cosmic rays 52 corona 52 orbits 52 Spitzer Space Telescope 51 gravitational 51 cosmic 51 Uranus 50 Earths 50 asteroids 50 vortices 49 filaments 48 Einstein theory 48 quarks 48 Pluto 48 solar flares 48 Universe 48 Saturn moon 48 asteroid 48 luminosity 48 gamma ray 47 orbiting 47 Harvard Smithsonian 47 Big Dipper 47 planetary 47 Big Bang 47 constellations 47 neutrons 46 habitable zone 46 organic molecules 46 particles 46 Cassini 46 Astrophysical Journal 46 Kepler 46 gravitational pull 46 photons 46 equator 46 Martian atmosphere 46 general relativity 46 Earth 46 planet 46 celestial 45 quark 45 sunspots 45 constellation 45 aurora 45 sunspot 45 spherical 45 outer layers 45 meteors 45 troposphere 45 hydrogen atoms 45 Planck 45 spectra 45 electrons