Planet Interiors The mass distribution of a planet can be probed by observing the motions of satellites (moons or spacecraft) in the planet's gravitational field. Mass lumps in the surface layer can be detected, as well as, asymmetries in the overall mass distribution. For example, the center of the Moon's mass is 2 kilometers closer to the Earth than the center of its overall shape (the geometric center). The Moon's crust on the Earth-facing side is several kilometers thinner than the crust on the far side. This is probably a remnant of the Earth's gravity acting on the early Moon's molten interior billions of years ago. Mars' center of mass is north of the geometric center. This is associated with the fact that Mars' southern cratered highlands stand about four kilometers higher than the northern volcanic plains. Planet interiors are warmer than outer space, so energy will flow outward from the interior toward the surface. There are three possible sources of heat in a planet's interior. One is the heat
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This note was uploaded on 12/15/2011 for the course AST AST1002 taught by Professor Emilyhoward during the Fall '10 term at Broward College.