Related by context. Frequent words. (Click for all words.) 44 Lunine 40 Smol 40 microbial ecology 40 Rignot 39 Geochemistry 37 Bottke 37 Poinar 36 biogeochemistry 36 Sinervo 36 NCAR scientist 36 Biogeography 35 geomorphology 34 Cassini radar 34 Zoback 33 planetary geologist 33 Alfred McEwen 33 biogeography 33 Melott 33 Earthlike 33 nanobacteria 32 Robock 31 biogeochemical 31 Ken Caldeira 30 Xiang Zhang 30 tectonics 29 Eric Rignot 29 planetary scientist 29 journal Geology 29 Paul Dirac 29 Cassini imaging 29 abiotic 28 hydrologic cycle 28 goethite 28 hydrological cycle 28 geochemist 27 Lobell 27 meteorite impacts 27 protozoan 27 foraminifera 27 decoherence 27 atmospheric chemistry 26 Nature Geoscience 26 geochemists 26 isotope ratios 26 glacial melt 26 Snowball Earth 26 oxygen isotope 25 Carnegie Institution 25 El Nino La Nina 25 Brownian motion 25 basaltic 24 marine sediments 24 Gliese #g 24 upwellings 24 ultracold 24 Cenozoic 23 Ice Ages 23 clathrates 23 lithosphere 22 Archaean 22 Technology Caltech 22 plate tectonics 22 Arctic Oscillation 22 Tibetan Plateau 21 Meridiani 21 terrestrial planets 21 polar caps 20 icy moons 20 supervolcano 20 Valles Marineris 20 sedimentary rock 19 poleward 19 heavily cratered 19 loess 19 magmas 19 Iapetus 19 polar vortex 19 icy crust 19 crustal 18 Sedna 18 equatorial regions 18 Tharsis 18 Scientists theorize 18 continental crust 18 Oort Cloud 17 gravitational interactions 17 ejecta 17 geologically active 17 Oort cloud 17 La Nina pattern 16 photosphere 16 polar craters 16 Martian dust 16 tropopause 16 protoplanetary disk 15 volcanism 14 magnetar 13 WASP #b 13 igneous 12 glaciation 11 Siberian permafrost