Related by context. Frequent words. (Click for all words.) 81 neutron stars 75 galaxies 75 supermassive black holes 74 pulsar 73 supernova 73 supernovae 73 quasar 69 quasars 69 galaxy 68 Milky Way galaxy 68 pulsars 68 gamma ray bursts 67 nebula 67 distant galaxies 66 Milky Way 66 brown dwarf 65 comet 64 gamma rays 64 gravitational 63 planets 63 neutrinos 63 comets 62 subatomic particles 61 exoplanets 61 nuclei 61 atoms 60 cosmic rays 60 magnetic fields 60 exoplanet 60 neutrons 59 extrasolar planets 59 astronomers 59 Saturn rings 58 Enceladus 58 particles 58 solar flares 58 outer layers 58 orbits 56 general relativity 56 astrophysicists 56 Kuiper Belt 56 asteroids 56 hydrogen atoms 56 proton 56 Solar System 56 corona 56 protons 55 electrons 55 gravitational pull 55 deuterium 55 photons 55 Astronomers 55 electron 54 asteroid 54 quark 54 Big Bang 54 galactic 54 fainter 54 magma 54 molten rock 54 quarks 54 gamma ray 54 asteroid belt 54 orbiting 53 impactor 53 water vapor 53 photon 53 particle 53 Einstein theory 52 meteor 52 gaseous 52 antimatter 52 filaments 51 Spitzer Space Telescope 51 plate tectonics 51 planetary 51 Galaxies 51 Earth crust 51 meteorites 50 luminosity 50 meteors 50 aurora 50 Tempel 1 50 organic molecules 50 moons 50 suns 49 cosmic 49 meteorite 49 velocities 49 chemical reactions 49 earth crust 49 convection 49 ions 49 sunspot 49 Higgs boson 48 starlight 48 universe 48 oscillations 48 Uranus 48 celestial bodies 48 Martian atmosphere