Related by context. Frequent words. (Click for all words.) 55 distant galaxies 54 galaxies 54 nebula 53 luminosity 53 quasar 53 quasars 53 Milky Way 53 galaxy 52 supernova 52 sunlight 52 sun 51 comet 51 astronomers 49 ionosphere 49 ultraviolet light 49 celestial 49 magnetic fields 49 extrasolar planets 49 cosmic rays 49 rays 48 neutron star 48 aurora 48 wavelengths 48 spectral 48 moons 48 photons 48 comets 48 exoplanet 48 gravitational 48 sun rays 48 Saturn rings 48 brightness 48 gamma rays 47 cosmos 47 moonlight 47 planets 47 Milky Way galaxy 47 constellations 47 luminescence 47 telescope 47 pulsar 47 telescopes 47 infrared wavelengths 46 exoplanets 46 Solar System 46 Astronomers 46 Sedna 46 fainter 46 Spitzer Space Telescope 45 refracted 45 supernovae 45 infrared 45 water vapor 45 celestial bodies 45 meteor shower 45 Pleiades 45 brown dwarf 45 moon 45 equatorial 45 moonlit 44 luminous 44 Cassini 44 photon 44 Cassini spacecraft 44 gamma ray 44 orbits 44 corona 43 galactic 43 MESSENGER 43 neutrinos 43 ultraviolet radiation 43 gamma ray bursts 43 dust particles 43 pulsars 43 neutron stars 43 meteor 43 UV light 43 asteroid belt 43 laser beams 43 radiance 43 refraction 43 Enceladus 43 diffraction 42 Saturn moon 42 transits 42 twinkling 42 fireflies 42 illumination 42 molten rock 42 solar flares 42 equinox 42 ultraviolet 42 spectra 42 supermassive black holes 42 cosmic 42 blackness 42 craters 42 solar eclipse 42 ultraviolet rays 41 suns 41 electrons