Related by context. Frequent words. (Click for all words.) 71 exosphere 64 photosphere 63 extrasolar 60 elemental composition 60 ultraviolet wavelengths 60 Earthlike 60 moon Enceladus 60 carbonate minerals 59 interstellar clouds 59 icy moons 59 photochemistry 58 noble gases 58 photometer 58 solar corona 58 Earth magnetosphere 58 interplanetary spacecraft 57 X ray telescopes 57 laser altimeter 57 Oort cloud 57 lunar craters 57 spectrographs 56 magnetosphere 56 helium atoms 56 ultracold 56 supercomputer simulations 56 substorm 56 Martian dust 56 CoRoT 7b 56 HiRISE camera 56 Kuiper belt 56 astrophysical 55 isotopic composition 55 radiative 55 photosynthetic organisms 55 infrared spectroscopy 55 Viking landers 55 Spectrometers 55 noctilucent clouds 55 force microscopy AFM 55 submillimeter 55 superlens 55 comet nucleus 55 radioactive decay 55 hydrogen helium 55 aerosol particles 55 chemical reactivity 55 cryosphere 55 infrared wavelength 55 polar craters 55 Oort Cloud 54 nanobubbles 54 tropospheric 54 meteoroids 54 gaseous planets 54 clathrates 54 Lunine 54 polar vortex 54 ALH# 54 magnetic reconnection 54 paramagnetic 54 oxygen isotopes 54 diffraction pattern 54 protoplanetary disk 54 ionize 54 ejecta 54 martian atmosphere 54 WASP #b 54 elliptical orbits 54 impactors 54 methane CH4 54 mesosphere 54 Gamma rays 54 planetary nebulae 54 solar nebula 54 geoid 53 biogeochemical 53 silicates 53 Earthlike planets 53 optical microscopy 53 ionized gas 53 coronagraph 53 SIRTF 53 baryons 53 shorter wavelengths 53 Hubble observations 53 Martian rocks 53 X ray emission 53 fluorescence microscope 53 spaceborne 53 alpha particles 53 magnetars 53 Diviner 53 ionisation 53 boron nitride 53 nicknamed Xena 53 isotope ratios 53 solids liquids 53 Exoplanet 53 Conductivity 53 radial velocity 53 tropopause