Related by context. Frequent words. (Click for all words.) 66 X ray Observatory 65 NASA Chandra 62 XMM Newton 59 Galaxy Evolution 57 X ray telescope 57 quasars 57 OSIRIS 56 astronomers 56 Solar Dynamics 56 ESO Very Large Telescope 56 gravitational lensing 56 Spitzer Space Telescope 55 microlensing 55 spacecraft orbiting 55 Keck Observatory 55 NASA Kepler 55 infrared telescope 55 Crab Nebula 55 solar corona 54 planets orbiting 54 Gamma Ray 54 optical telescopes 54 Very Large Telescope 53 Space Telescope 53 Very Large Array 53 radiometer 53 X ray emission 53 STEREO 53 Voyager spacecraft 53 HD #b [002] 53 Earth magnetosphere 53 Global Surveyor 53 Gemini Observatory 53 Gamma ray bursts 53 Chandra X ray 53 GRB # 53 distant galaxies 53 planet orbiting 53 COROT 53 OGLE 52 distant galaxy 52 extrasolar planet 52 STIS 52 NASA Cassini spacecraft 52 gamma ray 52 infrared wavelengths 52 orbiting telescope 52 telescope 52 interplanetary spacecraft 52 magnetar 52 Orion Nebula 52 elliptical galaxies 52 ionized gas 51 Kepler telescope 51 Astrophysicists 51 astronomical objects 51 spectroscopic 51 supernova remnant 51 NASA Mars Odyssey 51 gamma rays 51 cosmic ray 51 Astronomers 51 astronomical observations 51 Arecibo Observatory 51 WM Keck Observatory 51 NICMOS 51 astronomer 51 Spectrometer 51 quasar 51 gravitational wave 51 HRSC 51 astrophysicists 50 Cassini Huygens 50 habitable planets 50 interferometry 50 Hubble Space Telescope 50 gamma ray burst 50 NASA Hubble Space 50 Advanced Photon Source 50 WMAP 50 Telescope 50 Remote sensing 50 supernova explosion 50 scanning tunneling microscope 50 NASA ESA Hubble 50 Lick Observatory 50 Cassini spacecraft 50 orbiting 50 Hinode 50 Palomar Observatory 49 cosmic microwave background 49 Hubble observations 49 galaxy cluster 49 NASA Goddard 49 IceCube 49 Pan STARRS 49 orbiting Saturn 49 NASA Lunar Reconnaissance 49 Resolution Imaging 49 CMEs 49 Moderate Resolution