Related by context. Frequent words. (Click for all words.) 75 sunspot 62 solar flares 56 quasars 55 aurora 55 planets 54 extrasolar planets 54 supernovae 54 quasar 54 galaxies 54 gamma ray bursts 53 cosmic rays 53 Saturn rings 53 cosmic microwave background 53 volcanism 52 gravitational waves 52 comets 52 volcanic eruptions 52 meteors 52 gamma ray burst 52 Little Ice Age 52 distant galaxies 52 nebula 52 meteor showers 51 auroras 51 volcanic activity 51 moons 51 planets orbiting 51 exoplanets 51 Enceladus 51 magnetosphere 51 pulsars 51 brown dwarfs 51 supernovas 51 celestial bodies 51 magnetic fields 50 oscillations 50 corona 50 supernova 50 tropical cyclones 49 exoplanet 49 comet 49 pulsar 49 galaxy clusters 49 astronomers 49 ionosphere 49 Milky Way galaxy 49 infrared wavelengths 48 Uranus 48 gamma rays 47 meteor shower 47 equinox 47 vortices 47 brown dwarf 47 water vapor 47 neutron star 46 asteroids 46 atmospheric carbon dioxide 46 ozone depletion 46 troposphere 46 eruptions 46 Astronomers 46 mass extinctions 46 oscillation 46 supermassive black holes 46 Sedna 46 astrophysicists 46 extinctions 46 ultraviolet radiation 46 redshift 45 hydrogen atoms 45 vernal equinox 45 Milky Way 45 supermassive black hole 45 neutron stars 45 celestial objects 45 polar regions 45 greenhouse gas concentrations 45 elliptical orbit 45 lava flows 45 orbits 45 latitudes 45 northern latitudes 45 luminosity 45 UV radiation 45 contrails 45 El Niño 44 volcanoes 44 Martian atmosphere 44 equator 44 neutrinos 44 cosmological 44 atmospheric CO2 44 Earth 44 equatorial 44 La Niña 43 gamma ray 43 Solar System 43 La Nina 43 astronomer 43 photons 43 plate tectonics