Resonances and the Angular Momentum of the Earth-Moon System


Wednesday, December 14 2011 - 12:00 pm, PST
Matija Cuk
SETI Institute

The prevailing theory for the formation of the Moon is a giant collision between proto-Earth and a Mars-sized protoplanet, with the Moon being mainly made from the impactor's material. It is now known that the composition of the Moon is too similar to Earth's mantle to be derived from the impactor, seriously questioning the giant impact theory. However, this is a problem only if we assume that little or no angular momentum was lost from the system since its formation. While lunar tides keep the angular momentum in the system, certain resonances can transfer angular momentum to Earth's heliocentric orbit. These resonances are important if the Earth-Moon system formed with a much larger angular momentum, and can evolve the system to the present state. Dr. Cuk will show how it is likely that the Moon likely formed in a impact-triggered fission different from the "classical" giant impact scenario.

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