Earth Sciences 1086F/G Lecture Notes - Lecture 6: George Darwin, Terrestrial Planet, Giant-Impact Hypothesis
6 Nov 2018
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Document Summary
First proposed by george darwin more than 100 years ago: his father was charles darwin. The condensation hypothesis: also known as the contemporaneous formation hypothesis. In 1976/77 a new hypothesis proposed: that a planet smaller than earth (theia) that was in a progressibely unstable orbit around the sun gave earth a blow approx. Kinetic energy: energy a body has by virtue of its motion. Instead of retaining a large proportion of what was originally theia: tungsten (w) isoptopes tell us that the moon started life at least 30 million years after the start of the solar system. 2 papers published with further ideas in 2012: theia is almost the size of the earth. Instead of a low velocity impact a high velocity impact on a very smaller thiea. In order to spit out enough material to form the moon the earth has to be spinning really fast so that a day would only last for 2 hours.
