Related by context. Frequent words. (Click for all words.) 64 globular clusters 60 planetary nebulae 59 dwarf galaxies 59 planetary nebula 59 globular cluster 58 elliptical galaxies 58 active galactic nuclei 56 brown dwarfs 56 Pulsars 55 redshifts 55 Kuiper belt 55 Gamma ray bursts 55 interstellar dust 55 nebulae 55 supernova remnants 55 solar nebula 55 supernova remnant 55 astronomical objects 54 dwarf galaxy 54 Large Magellanic Cloud 54 Orion Nebula 54 X ray emission 54 distant galaxy 53 quasars 53 Crab Nebula 53 ejecta 53 hot Jupiters 53 distant galaxies 53 supernova explosions 52 meteoroids 52 brown dwarf 52 neutron stars 52 galaxy clusters 52 comet nucleus 52 galaxies 52 Galaxy Evolution 51 habitable planets 51 unaided eye 51 spherules 51 terrestrial planets 51 colliding galaxies 51 supernova explosion 51 star Gliese 51 rocky planets 50 Saturn rings 50 supernovae 50 photometry 50 super Earths 50 galaxy cluster 50 GRBs 50 spiral galaxies 50 magnetar 50 Milky Way Galaxy 50 nebula 50 redshift 50 Eta Carinae 50 planets circling 50 supernovas 50 Andromeda galaxy 49 Spitzer Space Telescope 49 Milky Way galaxy 49 spectroscopic 49 XMM Newton 49 accretion disk 49 galaxy 49 galaxy formation 49 optical telescopes 49 Sedna 49 ionized gas 49 HD #b [002] 49 Hubble observations 49 gravitational lensing 49 solar corona 48 starbursts 48 comets 48 Type Ia supernovae 48 extrasolar planet 48 silicates 48 Valles Marineris 48 accreting 48 planet orbiting 48 pulsars 48 WMAP 48 Kuiper Belt 48 Jupiter Saturn 48 Gamma rays 48 spiral galaxy 48 planets orbiting 48 visible wavelengths 48 Milky Way 48 X ray Observatory 48 Solar System 48 observable universe 48 planets 47 foraminifera 47 planet orbits 47 cosmic microwave background 47 interstellar medium 47 quasar 47 morphologies 47 Phaethon