Related by context. Frequent words. (Click for all words.) 56 moon Enceladus 55 icy moons 51 polar vortex 51 Earthlike 50 solar nebula 50 extrasolar 50 Kuiper belt 50 hydrologic cycle 50 gyres 50 manganese oxide 50 meteor impacts 50 Oort cloud 50 hydrological cycle 50 Martian dust 49 exosphere 49 heavily cratered 49 hydrothermal activity 49 meteorite impacts 49 interstellar clouds 49 planetesimals 49 photosphere 49 upwellings 48 Lake Vostok 48 lunar craters 48 Scientists theorize 48 atmospheric methane 48 polar craters 48 atmospheric phenomena 48 protoplanetary disk 48 supernova explosions 48 visible wavelengths 48 lithosphere 48 methane CH4 47 Oort Cloud 47 moon Titan 47 temperature gradients 47 Carina Nebula 47 interstellar dust 47 nanoporous 47 noble gases 47 Iapetus 47 atmospheric pollutants 47 hydrogen helium 47 polar caps 47 iridescence 47 manmade greenhouse gases 46 innermost planet 46 Gamma rays 46 reddish color 46 ionised 46 Saturn moon 46 Ultraviolet radiation 46 globule 46 feathered dinosaurs 46 Martian rocks 46 helium atoms 46 Meridiani 46 solar corona 46 X ray emission 46 volcanism 46 grainy texture 46 ALH# 46 cryosphere 46 reddish hue 46 comet tail 46 phytoplankton blooms 46 atmospheric circulation 45 tropopause 45 martian 45 Arctic permafrost 45 lavas 45 Eagle Nebula 45 gyre 45 Saturn moon Enceladus 45 graspable 45 interplanetary spacecraft 45 aurorae 45 supercooled 45 lunar soil 45 water vapor 45 CoRoT 7b 45 WASP #b 45 plankton blooms 45 bluish 45 Snowball Earth 45 protoplanetary disks 45 nanosized 45 iron oxides 45 emanation 45 Titan Saturn 45 aerosol particles 45 protoplasm 45 planetary nebulae 45 warmings 45 outer crust 45 supervolcano 44 red supergiant 44 Siberian permafrost 44 toroidal 44 photochemistry 44 polychromatic