Related by context. Frequent words. (Click for all words.) 50 Apophis 48 supernova explosion 48 asteroid 48 comet 47 meteor 46 mass extinction 46 volcanism 46 megatons 46 meteorite 46 greenhouse warming 45 gamma ray burst 45 solar flares 44 comets 44 Milky Way Galaxy 44 kiloton 44 impactor 43 cosmic ray 43 Chernobyl 42 mass extinctions 42 Chernobyl reactor 42 comet Tempel 1 42 Big Bang 42 glaciation 41 spacecrafts 41 Kamchatka 41 Chornobyl 41 HAARP 41 Smolensk 41 astrophysical 41 observatories 41 asteroids 41 astronomers 41 flying saucer 40 cometary 40 astrophysicists 40 neutron stars 40 Earth 40 Kuiper Belt 40 volcanic eruptions 40 volcanoes 40 distant galaxy 40 NEOs 40 extrasolar planet 40 galaxy clusters 39 Meteorites 39 neutrino 39 Phobos 39 Grimsvotn 39 meteor showers 39 collider 39 cataclysmic 39 Milky Way galaxy 39 orbital debris 39 Kursk 39 supernovas 39 exoplanets 39 geologic 39 meteor shower 39 Tempel 1 39 Roscosmos 39 UFO 39 moon Titan 39 plate tectonics 38 earthquakes 38 particle accelerator 38 supernova 38 supernovae 38 Saturn rings 38 seismologists 38 volcanic eruption 38 planets orbiting 38 Earths 38 brown dwarfs 38 quasar 38 alien spacecraft 38 gigatons 38 extrasolar planets 38 cosmological 38 Gamma Ray 38 neutron star 38 volcanic activity 38 Yakutia 38 Iapetus 38 Geophysical Institute 38 Enceladus 38 rocky planets 38 Sputnik 38 cosmic 38 meteors 38 magnetosphere 38 Earthlings 38 ICBM 38 Solar System 38 HD #b [002] 37 Krakatoa 37 Tupolev Tu 37 Katyn 37 outer planets 37 orbiting 37 cosmic rays 37 Atomic Scientists