Related by context. Frequent words. (Click for all words.) 73 Galaxy Evolution 66 XMM Newton 64 Spitzer Space Telescope 63 planetary nebulae 63 active galactic nuclei 63 infrared telescope 63 astronomical objects 62 distant galaxies 61 quasars 60 solar corona 60 NASA Cassini spacecraft 59 Hubble observations 59 X ray emission 59 Orion Nebula 59 interplanetary spacecraft 59 NASA Chandra 59 Gamma ray bursts 59 astronomers 59 COROT 59 spacecraft orbiting 59 elliptical galaxies 59 Voyager spacecraft 58 galaxies 58 Crab Nebula 58 supernova remnants 58 distant galaxy 58 globular clusters 58 spectroscopic 58 gamma ray burst 58 supernova remnant 58 infrared wavelengths 58 extrasolar planet 58 Andromeda galaxy 57 Chandra X ray 57 supernova explosion 57 GRBs 57 NASA Kepler 57 extrasolar planets 57 globular cluster 57 Saturn rings 57 celestial object 57 X ray Observatory 57 galaxy cluster 57 Large Magellanic Cloud 57 Saturn moon Enceladus 57 microlensing 56 dwarf galaxy 56 GRB # 56 Cassini 56 X ray telescope 56 Very Large Array 56 visible wavelengths 56 dwarf galaxies 56 HD #b [002] 56 interstellar dust 56 comet 56 telescope 56 comet nucleus 56 Very Large Telescope 56 Cassini Huygens 55 supernova explosions 55 astronomical observations 55 THEMIS 55 Space Telescope 55 orbiting observatory 55 cosmic microwave background 55 planetary nebula 55 magnetar 55 planets orbiting 55 rocky planets 55 Astrophysicists 55 quasar 55 gravitational lensing 55 gamma ray 55 colliding galaxies 55 auroral 55 hyperspectral 55 optical telescopes 55 brown dwarfs 55 WM Keck Observatory 55 habitable planets 54 NASA Lunar Reconnaissance 54 orbiting spacecraft 54 orbiting Saturn 54 Eta Carinae 54 galaxy formation 54 NASA ESA Hubble 54 Keck Observatory 54 WMAP 54 cosmic ray 54 planet orbiting 54 exoplanets 54 gamma ray bursts 54 supernova 54 ESO Very Large Telescope 54 Milky Way galaxy 54 star Gliese 54 gravitational wave 54 planets 54 Andromeda Galaxy 54 Cassini spacecraft