Lunar formation. Dating the Moon-forming impact event with asteroidal meteorites - PubMed (original) (raw)

. 2015 Apr 17;348(6232):321-3.

doi: 10.1126/science.aaa0602.

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Lunar formation. Dating the Moon-forming impact event with asteroidal meteorites

W F Bottke et al. Science. 2015.

Abstract

The inner solar system's biggest and most recent known collision was the Moon-forming giant impact between a large protoplanet and proto-Earth. Not only did it create a disk near Earth that formed the Moon, it also ejected several percent of an Earth mass out of the Earth-Moon system. Here, we argue that numerous kilometer-sized ejecta fragments from that event struck main-belt asteroids at velocities exceeding 10 kilometers per second, enough to heat and degas target rock. Such impacts produce ~1000 times more highly heated material by volume than do typical main belt collisions at ~5 kilometers per second. By modeling their temporal evolution, and fitting the results to ancient impact heating signatures in stony meteorites, we infer that the Moon formed ~4.47 billion years ago, which is in agreement with previous estimates.

Copyright © 2015, American Association for the Advancement of Science.

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