MIT OpenCourseWarehttp://ocw.mit.edu 12.002 Physics and Chemistry of the Earth and Terrestrial Planets Fall 2008 For information about citing these materials or our Terms of Use, visit: http://ocw.mit.edu/terms..12.002 Physics and Chemistry of the Terrestrial Planets Planetary HistoriesFive Terrestrial PlanetsEarth • Radius 6400 km, Mass 1 Earth Mass, • Density 5.5 g cm-3 (uncompressed: 4.05 g cm-3), I/MR2 =0.33 • Semimajor axis 1 AU • Average surface temp 288 K • Dynamo magnetic field • Continental and oceanic crust • Plate tectonics and active volcanism • Oceans of liquid water • Atmosphere of N2 and O2 •LifeMars • Radius 3400 km, Mass 0.1 Earth Mass, • Density 3.9 g cm-3 (uncompressed: 3.7 g cm-3), I/MR2 =0.37 • Semimajor axis 1.5 AU • Average surface temp 210 K • Crustal remanent magnetic field, no dynamo • Hemispherical crustal dichotomy • Probably no late tectonics but active volcanism • Water not stable in liquid form, small amounts of water • Atmosphere of CO2 •Life?Moon • Radius 1700 km, Mass 0.01 Earth Masses • Density 3.3 g cm-3 (uncompressed: 3.3 g cm-3), I/MR2 =0.39 • Semimajor axis 1 AU • Surface temp ranges 40-400 K • Weak crustal remanent field, no dynamo • Highlands and mare • Probably no late tectonics, not volcanically active • No water, extremely dry • Tenuous H2, He atmosphere •No LifeMercury • Radius 2400 km, Mass 0.05 Earth Masses • Density 5.4 g cm-3 (uncompressed: 5.3 g cm-3), I/MR2 = 0.33 • Semimajor axis 0.4 AU • Surface temp ranges 40-750 K • Weak crustal remanent field or dynamo • Cratered surface of unknown composition • Probably no late tectonics, not volcanically active • Little water, extremely dry (ice at poles!) • Tenuous O, H2, He atmosphere •No LifeVenus • Radius 6000 km, Mass 0.8 Earth Masses • Density 5.25 g cm-3 (uncompressed: 4.0 g cm-3), I/MR2 = 0.33 • Semimajor axis 0.7 AU • Average surface temp 750 K • No magnetic field • Cratered surface of unknown composition • Volcanically and tectonically active • Extremely dry • Thick (92 bar) CO2 atmosphere •No
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