Related by context. Frequent words. (Click for all words.) 62 XMM Newton 61 astronomers 59 optical telescopes 59 telescopes 58 astrophysical 58 WMAP 58 gravitational lensing 57 occultation 57 extrasolar planets 57 astrophysicists 56 observatories 55 GRBs 55 astronomy 55 adaptive optics 55 celestial bodies 55 NASA Chandra 55 telescope 55 redshift 54 WM Keck Observatory 54 extrasolar planet 54 interferometry 54 X ray Observatory 53 NASA Cassini spacecraft 53 interferometer 53 spectroscopic 53 Saturn rings 53 cosmologists 53 IceCube 52 Very Large Telescope 52 gamma ray burst 52 quasars 52 cosmic ray 52 brown dwarfs 51 general relativity 51 cosmology 51 spectrometers 51 supernovae 51 Spitzer Space Telescope 51 distant galaxies 51 cosmic microwave background 51 HD #b [002] 51 gamma ray bursts 51 spectroscopy 51 gravitational waves 51 planets 51 elliptical galaxies 51 pulsars 51 exoplanet 51 Cassini 51 globular clusters 50 astronomer 50 cosmological 50 Einstein theory 50 celestial objects 50 Kepler 50 Huygens 50 exoplanets 50 planetary 50 THEMIS 50 cosmic rays 50 optical telescope 49 amateur astronomers 49 Astronomers 49 interstellar dust 49 dynamical 49 physicists 49 solar eclipses 49 measurements 49 GOCE 49 Envisat 49 neutrinos 49 NASA Mars Odyssey 49 gamma ray 49 Astrophysical Journal 49 seismology 49 supernovas 49 orbiting spacecraft 49 observations 48 galaxies 48 computer simulations 48 galaxy clusters 48 auroras 48 Astronomy 48 X ray diffraction 48 polar regions 48 comet nucleus 48 astrophysics 48 optical microscope 48 isotopic 48 Space Telescope 48 spectrometer 48 flybys 48 moon Europa 48 Hubble Telescope 48 spectra 48 celestial 48 JWST 48 distant galaxy 48 constellations 48 observatory 47 precise measurements