Related by context. Frequent words. (Click for all words.) 60 planetary nebula 59 comet tail 58 haloes 57 photosphere 57 Eagle Nebula 57 Carina Nebula 57 galaxy NGC 57 noctilucent clouds 56 polar vortex 56 supernova remnant 55 auroral 55 X ray emission 55 meteoroid 55 aurorae 55 Halley comet 55 iridescence 54 red supergiant 54 Martian dust 54 ultraviolet wavelengths 54 planet Uranus 54 exosphere 54 nebulae 54 protostars 54 supernova remnants 54 planetary nebulae 54 gravitational lens 54 solar corona 53 constellation Virgo 53 Oort Cloud 53 supernova explosion 53 magnetar 53 colliding galaxies 53 interstellar dust 53 ejecta 53 interplanetary spacecraft 53 moonlets 53 Crab Nebula 53 orb 53 photometer 52 polar craters 52 constellation Orion 52 supernova 52 Galaxy Evolution 52 ionized gas 52 Lunar eclipse 52 Solar flares 52 dwarf galaxy 52 celestial object 52 supermoon 52 moon Enceladus 52 infrared wavelength 52 accretion disk 52 flashbulb 52 nebulas 52 cirrus 52 metallicity 52 cirrus clouds 52 constellation Leo 52 Supernovae 52 fluorescing 51 starburst 51 SIRTF 51 Meteor Shower 51 substorm 51 Hawking radiation 51 plasmon 51 Andromeda Galaxy 51 cumulus 51 Saturn rings 51 comet 51 diffracted 51 magnetars 51 Andromeda galaxy 51 protostar 51 noble gases 51 constellation Perseus 51 Nibiru 51 gamma ray burst 51 corona 51 diffraction pattern 51 icy moons 51 starbursts 50 cumulus clouds 50 supernovas 50 phosphorescence 50 cosmic microwave background 50 meteor 50 meteoroids 50 supernova explosions 50 Aurora Borealis 50 puffy clouds 50 constellation Gemini 50 soundwaves 50 aurora 50 constellation Sagittarius 50 photoluminescence 50 coronal mass ejection 50 Cassini imaging 50 cometary 50 solar nebula 50 galaxy cluster