Related by context. Frequent words. (Click for all words.) 80 astrophysicists 78 Astronomers 72 astronomer 69 physicists 67 galaxies 67 extrasolar planets 67 quasars 66 telescopes 65 amateur astronomers 65 gamma ray bursts 65 supernovae 64 planets 64 distant galaxies 63 quasar 63 telescope 63 exoplanets 62 pulsars 62 exoplanet 62 Spitzer Space Telescope 62 observatories 61 comets 61 Saturn rings 61 supernova 61 astronomy 60 scientists 59 Milky Way 59 Cassini 59 neutron star 59 Physicists 59 Milky Way galaxy 59 neutron stars 58 pulsar 58 comet 58 Cassini spacecraft 57 nebula 57 stargazers 57 brown dwarf 57 Telescope 57 cosmic rays 57 orbiting 56 celestial bodies 56 observatory 56 Solar System 56 paleontologists 56 Astronomy 55 Astrophysics 55 asteroid 55 Astronomer 55 galaxy 55 astrophysicist 55 neutrinos 55 Hubble Space Telescope 54 amateur astronomer 54 supermassive black holes 54 Enceladus 54 asteroids 53 Kuiper Belt 53 solar flares 53 aurora 53 gamma rays 52 Hubble 52 Astrophysical Journal 52 Huygens 52 seismologists 51 orbits 51 Hubble telescope 51 celestial 51 moons 51 planetary 51 general relativity 51 MESSENGER 51 Scientists 51 gamma ray 51 starlight 51 meteor shower 51 astrophysics 51 researchers 50 Planck 50 Pluto 50 Observatory 50 meteorites 50 archaeologists 50 subatomic particles 50 Einstein theory 50 cosmological 49 sunspot 49 geologists 49 meteors 49 spacecraft 49 LCROSS 49 neuroscientists 49 cosmology 49 flyby 49 Mars Reconnaissance Orbiter 49 sunspots 49 spectroscopy 49 Higgs boson 49 IAU 49 magnetic fields 48 spectra 48 cosmic