Related by context. Frequent words. (Click for all words.) 79 X ray Observatory 68 Spitzer Space Telescope 66 XMM Newton 65 Space Telescope 61 astronomers 61 Very Large Telescope 61 Chandra X ray 60 quasars 60 NASA Cassini spacecraft 60 galaxy clusters 59 supernovae 59 gamma ray bursts 59 distant galaxies 59 gamma ray burst 59 WMAP 58 supernova explosion 57 distant galaxy 57 supernova 56 Astronomers 56 galaxies 55 quasar 55 neutron star 55 elliptical galaxies 55 supernovas 55 pulsars 55 astrophysicists 55 extrasolar planets 55 NASA Hubble Space 54 galaxy cluster 54 gravitational waves 54 globular clusters 54 cosmic microwave background 54 Telescope 54 spectroscopic 54 planets orbiting 53 exoplanet 53 Astrophysical Journal 53 Hubble Space Telescope 53 redshift 53 planet orbiting 53 extrasolar planet 53 exoplanets 53 telescopes 52 Saturn rings 52 pulsar 52 neutron stars 52 Astrophysics 52 Milky Way Galaxy 52 telescope 51 Gamma Ray 51 adaptive optics 51 gamma ray 51 Milky Way galaxy 51 supermassive black hole 51 Cassini 51 cosmologists 51 auroras 51 HD #b [002] 51 nebulae 51 Astrophysical Journal Letters 50 rocky planets 50 supermassive black holes 50 dwarf galaxies 50 brown dwarfs 50 Solar System 50 Cassini spacecraft 50 Hubble Telescope 50 NASA Aqua 50 solar flares 50 cosmic rays 49 GLAST 49 cosmic ray 49 Milky Way 49 NASA Mars Reconnaissance 49 cometary 49 STEREO 49 Harvard Smithsonian 49 planets 49 infrared wavelengths 48 comets 48 LCROSS 48 neutrinos 48 nebula 48 NASA Mars Odyssey 48 comet 48 ringed planet 48 Envisat 48 Mars Reconnaissance Orbiter 48 gamma rays 48 Black Holes 48 brown dwarf 48 Saturn moons 48 HiRISE 48 Hubble 48 Einstein theory 47 CMEs 47 astrophysical 47 spiral galaxy 47 orbiting 47 THEMIS 47 positrons