Related by context. Frequent words. (Click for all words.) 73 magnetosphere 63 interstellar space 58 nebula 58 Solar System 58 infrared wavelengths 58 ionosphere 57 Milky Way galaxy 57 gravitational 57 Kuiper Belt 57 Saturn rings 56 neutron star 56 magnetic fields 56 galaxies 56 galaxy clusters 56 cosmic rays 55 galaxy 55 cosmic microwave background 55 planets 55 distant galaxies 55 comet 54 infrared radiation 54 corona 54 quasar 53 Martian atmosphere 53 gravitational waves 53 polar regions 53 cosmos 53 extrasolar planets 53 comets 52 orbits 52 cosmic radiation 52 gamma rays 52 Milky Way 52 universe 52 Uranus 52 rocky planets 52 vortices 51 brown dwarfs 51 brown dwarf 51 Enceladus 51 troposphere 51 quasars 51 elliptical orbit 51 nuclei 51 asteroid belt 51 gamma ray burst 51 aurora 51 supermassive black hole 50 redshift 50 neutron stars 50 exoplanets 50 hydrogen atoms 50 exoplanet 50 pulsar 50 photons 50 celestial bodies 50 Einstein theory 50 water vapor 50 outer layers 50 biosphere 49 THEMIS 49 nebulae 49 equator 49 WMAP 49 albedo 49 interstellar 49 supermassive black holes 49 astronomers 49 atomic particles 49 MESSENGER 49 atoms 49 galactic 48 supernova 48 polar 48 outer layer 48 nanotube 48 filaments 48 planets orbiting 48 protons 48 Sedna 48 sunspots 48 dynamical 48 general relativity 48 martian 48 impactor 48 landforms 48 gamma ray bursts 48 planetary 47 moon Titan 47 neutrino 47 neutrinos 47 auroras 47 microtubules 47 gravitational pull 47 outermost 47 solar flares 47 quantum mechanical 47 cosmologists 47 convective 47 electrons 47 Tempel 1