Related by context. Frequent words. (Click for all words.) 68 NASA Chandra 66 X ray Observatory 65 Very Large Telescope 64 XMM Newton 64 NASA Cassini spacecraft 62 planets orbiting 62 astronomers 61 NASA Hubble Space 61 extrasolar planets 61 distant galaxy 61 distant galaxies 60 Astronomers 60 Chandra X ray 60 Cassini spacecraft 60 exoplanet 59 brown dwarf 59 WMAP 58 globular clusters 58 galaxies 58 Space Telescope 58 rocky planets 58 Milky Way galaxy 58 quasars 57 exoplanets 57 planet orbiting 57 supernovae 57 nebula 57 telescopes 57 NASA Mars Reconnaissance 56 galaxy clusters 56 spectroscopic 56 infrared wavelengths 56 gamma ray burst 56 brown dwarfs 56 Cassini 56 supernova 56 telescope 55 comet 55 nebulae 55 gamma ray bursts 55 Saturn rings 55 cosmic microwave background 55 planets 54 quasar 54 moon Titan 54 Saturn moon 54 Hubble Space Telescope 53 interstellar dust 53 Enceladus 53 comets 53 Mars Reconnaissance Orbiter 52 galaxy 52 astrophysicists 52 supernovas 52 Kuiper Belt 52 Solar System 52 observatories 52 Milky Way 51 Cassini Huygens mission 51 neutron star 51 THEMIS 51 Astrophysics 51 pulsars 51 ringed planet 51 infrared radiation 51 dwarf galaxies 51 Telescope 51 spiral galaxy 51 HiRISE 51 adaptive optics 51 orbiting 50 pulsar 50 comet dust 50 redshift 50 Mars Global Surveyor 50 Iapetus 50 MESSENGER 50 LCROSS 50 NASA Goddard 50 moons 50 amateur astronomers 50 Astrophysical Journal Letters 50 asteroids 50 Cassini orbiter 50 supermassive black hole 50 Astrophysical Journal 49 spiral galaxies 49 celestial objects 49 neutron stars 49 Planck 48 Spectrometer 48 Betelgeuse 48 supermassive black holes 48 Gliese 48 Lunar Reconnaissance Orbiter 48 flyby 48 Hubble telescope 48 astrophysical 48 Sedna 48 Envisat 48 comet Tempel 1