MARS The Martian day is very nearly the same length as the terrestrial day - 24h 37m and 22s. Mars has an orbital eccentricity of e = 0.0934, which is much larger than earth and Venus. This makes a substantial difference to the sunlight received at perihelion and aphelion - (1+e)2/(1-e)2 is around 1.4545. i.e a 45% difference. This has a considerable effect on its climate. Mars has two natural satellites, Phobos and Deimos. It also has a Trojan asteroid companion - 5261 Eureka, a 2km diameter body. Phobos orbits inside the synchronous altitude (i.e. it rises in the west and sets in the east), and is gradually spiralling in. Deimos orbits outside the synchronous altitude and is gradually spiralling out. The orbital periods and semi-major axes of these satellites mean we can determine MM, which is about 0.01076ME. This gives a mean density MM/VM of 3940 kg m-3 (compared to earth's 5524). The difference with earth is not as great as it sounds, since earth is much more compressed by self-gravity. If we calculate the
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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.