Related by context. Frequent words. (Click for all words.) 51 Changizi 51 GALEX 50 Seth Shostak 49 Lunine 48 Sara Seager 48 extrasolar 48 AGNs 48 interplanetary spacecraft 48 galaxy formation 48 journal Icarus 48 Pasachoff 48 CfA 48 Alivisatos 48 gravitational wave 47 STScI 47 Cepheids 47 Lyman alpha 47 VIRTIS 47 Carnegie Observatories 47 astronomical objects 46 planetary nebulae 46 submillimeter 46 Earthlike 46 Michael A'Hearn 46 Alfred McEwen 46 Martian meteorites 45 faraway galaxies 45 distant galaxy 45 AKARI 45 nebulas 45 Robock 45 Udry 45 astrophysical 45 galactic cosmic rays 45 Eagle Nebula 45 quasars 45 Oort Cloud 45 Cassini imaging 45 GRBs 45 Type Ia supernova 44 WASP #b 44 magnetars 44 submicroscopic 44 XMM Newton 44 Hubble Ultra 44 Oort cloud 44 gravitational lensing 44 cosmic particles 44 icy moons 44 subatomic 44 faintly visible 44 exosphere 44 Carl Pilcher 43 nicknamed Xena 43 diffracted 43 distant galaxies 43 redshift 43 protoplanetary disks 43 haloes 43 elemental composition 43 solar corona 43 Epsilon Eridani 43 photochemistry 43 Cassini radar 43 lunar craters 43 galaxies 43 elliptical galaxies 43 active galactic nuclei 43 Planetary Science Institute 43 Voyager spacecraft 43 Yakobson 43 cosmic ray 42 cosmologists 42 planet Uranus 42 Exoplanet 42 Earthlike planets 42 Wilkinson Microwave Anisotropy Probe 42 coronagraph 42 National Astronomical Observatory 42 metallicity 42 cosmic microwave background 42 microscopic 42 Keck telescope 42 transiting planets 42 Type Ia 42 Galaxy Evolution 42 Gamma ray bursts 42 observable universe 42 Lowell Observatory 42 Keck Observatory 42 HD #b [002] 42 Astrophysics Laboratory 42 globular clusters 42 magnetar 42 astronomer 42 Martian dust 41 nebulae 41 A'Hearn 41 Toutatis 41 supernovae 41 Crutzen