Related by context. Frequent words. (Click for all words.) 66 Orion Nebula 62 X ray emission 61 Crab Nebula 61 nebula 61 nebulae 60 distant galaxies 60 XMM Newton 60 globular cluster 60 Andromeda galaxy 60 supernova remnants 59 planetary nebula 59 galaxy cluster 59 Andromeda Galaxy 59 distant galaxy 59 supernova remnant 58 Eta Carinae 58 Galaxy Evolution 58 Milky Way Galaxy 58 supernova explosion 57 Large Magellanic Cloud 57 Kuiper belt 57 spiral galaxy 56 elliptical galaxies 56 visible wavelengths 56 brown dwarfs 56 Spitzer Space Telescope 56 brown dwarf 56 ionized gas 56 Milky Way galaxy 55 quasars 55 galaxy clusters 55 quasar 55 infrared wavelengths 55 Saturn rings 55 galaxies 55 Betelgeuse 55 magnetar 55 globular clusters 55 supernova explosions 55 Mimas 55 unaided eye 55 HD #b [002] 54 gravitational lensing 54 microlensing 54 Milky Way 54 Cancri 54 galaxy formation 54 constellation Leo 54 astronomical objects 54 Saturn moons 54 comet nucleus 54 COROT 54 constellation Orion 54 supernovas 53 volcanically active 53 ringed planet 53 planets orbiting 53 Fomalhaut 53 X ray Observatory 53 cosmic microwave background 53 GRBs 53 spiral galaxies 53 accretion disk 53 extrasolar planets 53 astronomers 53 dwarf galaxy 53 dwarf galaxies 53 ESO Very Large Telescope 53 GRB # 53 planet orbits 53 redshift 53 NASA Chandra 52 NASA ESA Hubble 52 corona 52 solar nebula 52 Type Ia supernovae 52 WMAP 52 Gamma ray bursts 52 Saturn moon Enceladus 52 Saturn moon 52 moons 52 gamma rays 52 gamma ray 52 galaxy 52 celestial object 51 auroral 51 NASA Cassini spacecraft 51 observable universe 51 interstellar dust 51 gamma ray burst 51 VLBA 51 ejecta 51 Sedna 51 supermassive black hole 51 NGC 51 Gliese #g 51 Comet McNaught 51 exoplanets 51 supernovae 51 suns 51 extrasolar planet