Ch.9_Moon[1] - C h.9 Moon 3 theories in Moon formation The...

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Ch.9 Moon 3 theories in Moon formation The first involved an event, in which Moon broke off from a rapidly spinning Earth. A second theory proposed that Earth’s satellite formed contemporaneously as a gravitationally bound pair. The third theory suggested that Moon formed as an independent planetary body that was later "captured" by Earth during a close pass. Reasons for rejection it was difficult in both the capture and co-formation models to account for the lack of a large lunar iron core, because both predicted that Moon formed from the same mix of materials as the terrestrial planets, which typically contain a more substantial abundance of iron. In-pact scenario- In 1976 and 1977 the giant impact scenario was hypothesized. The idea was that a side-swipe by a roughly Mars-sized body with early Earth could provide Earth with its high initial spin, needed to explain the current system's motion, and eject enough debris into orbit to form Moon. If the ejected material came primarily from the mantles of the Earth and the impactor, the lack of a sizeable lunar core was easily understood, and the energy of the impact could account for the extra heating of lunar material required by lunar volatile depletions. About 445 bya ago.
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This note was uploaded on 11/01/2010 for the course EARTH SCIE 2010 taught by Professor Neil during the Fall '10 term at UWO.

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Ch.9_Moon[1] - C h.9 Moon 3 theories in Moon formation The...

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