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Unformatted text preview: MERCURY Mercury has a mass of 0.056 M E . This has been determined from the pass of the EROS asteroid and refined by the flyby of Mariner 10, since it has no natural satellites to give the relevant period/orbital radius data. It takes 58.64 days to rotate about its axis, and there is an exact 3:2 ratio between its orbital and axial rotation rates (sidereal). Thus one side of its long axis faces the Sun at every other perihelion. Mercury's density is very high. Its radius is 2440km, so its density is 5430 kg m-3 . This is between the values of Earth and Mars, but this is largely uncompressed, suggesting there must be a large iron core over a silicate mantle. (Models suggest 80% core and a silicate mantle, though t silicate mantle, though there could be less silicates and more FeO and FeS in the core. Why should it be so dense? This is presumably because it was formed after the most volatile material had been dispersed from near the Sun by solar heating in the early solar system; an alternative...
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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.
- Fall '10