Lecture17 - All have similar bulk chemical composition,...

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Survey of terrestrial planets All have similar bulk chemical composition, dominated by O, Mg, Si, Fe Fraction of total mass in metallic iron decreases with increasing distance from the Sun (Mercury Mars) Table below which roughly ranks the importance of various surface influences on each terrestrial body; 3 is most important and 0 no significance. Planet Impacts Volcanism Tectonics Erosion Moon 3 1 0-1 0 Mercury 3 1 0-1 0 Mars 2 2 2 1-2 Venus 1 3 3 0-1 Earth 1 3 3 3 Bodies are listed in order of increasing mass; ¾ impacts become less important as mass increases, ¾ both volcanism and tectonics become more important as mass increases, ¾ erosion (atmosphere and surface water) effects are also more important as mass increases. Planetary mass influences planetary evolution. ¾ The amount of internal heating and the rate at which a planet cools are key. ¾ All of the heating mechanisms depend on mass (proportional volume or R 3 ) while cooling depends on surface area (proportional to R 2 ). Consequently the larger body will cool more slowly/retain internal heat longer.
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The Smallest Moons Small moons are characterized by: ¾ Heavy or saturated cratering ¾ Irregular shapes Deimos: smooth and blanketed by regolith Phobos: ¾ Dark, coated with carbonaceous material ¾ Low density (porous) ¾ 100m regolith. But more rugged, grooved terrain than Deimos. More recent impact? Impacts knock debris off these moons, form “dust belts” which continue to sandblast the surface and add to the regolith Amalthea is a small moon of Jupiter that is unusually
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This note was uploaded on 04/15/2009 for the course PHYS 275 taught by Professor Harris during the Winter '09 term at Waterloo.

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Lecture17 - All have similar bulk chemical composition,...

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