Related by context. Frequent words. (Click for all words.) 60 terrestrial planets 60 radial velocity 59 magnetic reconnection 59 planetary nebulae 58 auroral 58 galaxy formation 57 planets 57 extrasolar planets 57 habitable planets 57 globular clusters 57 dynamical 57 globular cluster 57 comets 56 interplanetary spacecraft 56 microlensing 56 supernova explosion 56 elliptical galaxies 55 Kuiper belt 55 Saturn rings 55 Earth magnetosphere 55 microsatellites 55 astrophysical 55 oxygen isotopes 55 asteroids 55 EPOXI 55 solar nebula 55 extrasolar planet 55 rocky planets 54 neutrino 54 morphologies 54 planetary 54 spherules 54 substorms 54 brown dwarf 54 nuclei 54 cometary 54 orbiting spacecraft 54 lava tubes 54 GRBs 54 dwarf galaxy 54 accretion disk 54 supernova remnants 54 solar corona 54 supernova explosions 54 neutron star 53 meteoroid 53 COROT 53 Hubble observations 53 magnetar 53 super Earths 53 dwarf galaxies 53 active galactic nuclei 53 Type Ia supernovae 53 X ray emission 53 Saturn moons 53 interferometry 53 outer planets 53 supernovae 53 neutron stars 53 Jupiter moons 53 anisotropy 53 brown dwarfs 53 galaxies 53 cosmic ray 53 moon Charon 53 convective 53 ejecta 53 colliding galaxies 53 THEMIS 53 spectroscopic 53 Voyager spacecraft 53 numerical simulations 52 distant galaxies 52 Higgs particle 52 innermost planet 52 quasar 52 asteroid 52 habitable zones 52 Cosmic rays 52 orbits 52 quasars 52 magmatic 52 HD #b [002] 52 Hawking radiation 52 planets orbiting 52 electron density 52 magnetosphere 52 singularities 52 exoplanets 52 Titan Saturn 52 Saturn moon 52 Computer simulations 52 gravitational waves 52 colliders 52 Galaxy Evolution 52 quantum entanglement 52 spiral galaxies 52 Milky Way Galaxy 51 hot Jupiters 51 gravitational lensing 51 excitons