Related by context. Frequent words. (Click for all words.) 56 constellations 55 Milky Way 54 nebula 54 Cassiopeia 54 constellation 53 nebulae 53 distant galaxy 52 astronomers 52 Perseids 51 Arcturus 51 spiral galaxy 51 Spica 51 Big Dipper 51 celestial objects 50 extrasolar planets 50 planets 50 orbits 49 Sedna 49 quasars 49 orbiting 49 Pollux 49 celestial bodies 49 planet orbiting 49 aurora 48 crescent moon 48 distant galaxies 48 galaxies 48 vernal equinox 48 Astronomers 48 Halley Comet 48 gamma ray bursts 48 equinox 47 meteors 47 astronomy 47 meteor shower 47 Aldebaran 47 brown dwarf 47 planets orbiting 46 celestial 46 astrophysicists 46 moons 46 Saturn rings 46 Andromeda 46 Milky Way galaxy 46 galaxy 46 quasar 46 brown dwarfs 46 Solar System 46 spring equinox 46 Nebula 46 Spitzer Space Telescope 46 equator 45 redshift 45 elliptical orbit 45 infrared wavelengths 45 starlight 45 cosmos 45 exoplanets 45 supernova 45 Gliese 45 supernovas 44 auroras 44 fainter 44 Galaxies 44 telescopes 44 Aurora Borealis 44 Very Large Telescope 43 luminosity 43 Astronomy 43 asteroid belt 43 comets 43 Phobos 43 telescope 43 supernovae 43 Lowell Observatory 43 comet 43 Cygnus 43 Saturn 43 orbited 43 suns 43 gamma ray burst 43 summer solstice 43 Uranus 42 Cassini 42 Regulus 42 gravitational waves 42 Telescope 42 neutron star 42 Venus 42 Stargazers 42 amateur astronomers 41 THEMIS 41 Sagittarius 41 aurora borealis 41 Planets 41 dwarf galaxies 41 lunar eclipse 41 Hubble Space Telescope 41 NGC 41 ESO 40 ellipse