Related by context. Frequent words. (Click for all words.) 56 Cassini 56 Kepler 55 distant galaxies 54 Huygens 54 spectroscopic 54 cosmic microwave background 53 LCROSS 51 exoplanet 51 galaxy clusters 51 infrared wavelengths 51 lunar surface 51 LRO 50 astronomers 50 gamma ray bursts 50 brown dwarfs 50 Hubble 50 galaxies 50 NASA Goddard 50 Space Telescope 50 exoplanets 50 planets 50 Solar System 49 Saturn rings 49 spectrometer 49 MESSENGER 49 gravitational waves 49 extrasolar planets 49 Spitzer Space Telescope 48 redshift 48 Hubble Space Telescope 48 spectroscopy 48 neutrino 48 supernovae 48 neutron stars 48 STEREO 48 cosmologists 48 Herschel 47 cosmos 47 quasars 47 Telescope 47 gamma ray burst 47 comet 47 quasar 47 Phobos 47 cosmic rays 47 telescope 47 astrophysicists 47 neutron star 46 pulsar 46 pulsars 46 NASA Chandra 46 spacecraft 46 magnetosphere 45 orbits 45 gamma ray 45 Orbiter 45 flyby 45 spectrometers 45 photons 45 Fermi 45 celestial objects 45 wavelengths 45 celestial bodies 45 Milky Way 45 Hubble Telescope 45 planets orbiting 45 spectrograph 45 Very Large Telescope 45 Mars Reconnaissance Orbiter 45 cosmic 45 adaptive optics 44 Astrophysics 44 Mars 44 Enceladus 44 orbiting 44 rocky planets 44 impactor 44 diffraction 44 Charon 44 gamma rays 44 Einstein theory 44 brown dwarf 44 photon 44 comets 44 telescopes 43 Milky Way galaxy 43 Tempel 1 43 quantum mechanical 43 supernovas 43 spectra 43 orbiter 43 galaxy 43 orbital 43 Hubble telescope 43 planetary 43 supernova 43 Cassini spacecraft 43 Space Agency 43 asteroids 43 relativistic 43 panoramic camera