Related by context. Frequent words. (Click for all words.) 75 sunspots 58 gamma ray burst 57 aurora 56 solar flares 55 quasar 55 cosmic ray 54 supernovae 54 geomagnetic field 53 supernova 53 exoplanet 53 Perseids 52 brown dwarf 52 distant galaxy 52 nebula 52 convective 51 planets orbiting 51 NASA Cassini spacecraft 51 Betelgeuse 51 cosmic microwave background 50 volcanism 50 extrasolar planets 50 Milky Way galaxy 50 pulsar 50 planet orbiting 50 comet 50 gamma ray bursts 50 Saturn rings 50 galaxies 49 THEMIS 49 astronomers 49 meteor shower 49 auroras 49 oscillations 49 neutron star 49 Sedna 49 pulsars 48 brown dwarfs 48 volcanic activity 48 meteors 48 Enceladus 48 spiral galaxy 48 quasars 48 magnetosphere 48 perturbation 48 glaciation 47 cosmic rays 47 ionosphere 47 supernovas 47 Cassiopeia 47 troposphere 47 planets 47 exoplanets 47 redshift 47 Little Ice Age 47 fainter 47 dwarf galaxies 46 equatorial 46 neutrino 46 gamma rays 46 distant galaxies 46 infrared wavelengths 46 HiRISE 46 Space Telescope 46 STEREO 46 Gliese 46 galaxy clusters 46 corona 46 supermassive black hole 46 spectra 46 Iapetus 46 orbits 46 oscillation 45 climatological 45 rocky planets 45 martian 45 lava flows 45 meteor showers 45 heliosphere 45 Milky Way 45 seismicity 45 galaxy 45 Uranus 45 equinox 45 photons 45 gamma ray 45 comets 45 dynamical 45 eruptions 45 planetary 45 NASA Chandra 45 astrophysicists 45 vernal equinox 44 Cassini 44 positrons 44 polar 44 ellipse 44 tropical cyclones 44 gravitational waves 44 volcanic eruptions 44 Holocene 44 photon