[meteorite-list] A primordial origin for the compositional similarity between the Earth and the Moon

From: Shawn Alan <shawnalan_at_meteoritecentral.com>
Date: Wed, 08 Apr 2015 15:09:56 -0700
Message-ID: <20150408150956.e8713c95af9984a493c5db01816d4c10.43667cb0ec.wbe_at_email22.secureserver.net>

Hello Listers

More info on the Earth and Moon.


Shawn Alan
IMCA 1633
ebay store http://www.ebay.com/sch/imca1633ny/m.html
Website http://meteoritefalls.com

A primordial origin for the compositional similarity between the Earth
and the Moon

Most of the properties of the Earth?Moon system can be explained by a
collision between a planetary embryo (giant impactor) and the growing
Earth late in the accretion process1, 2, 3. Simulations show that most
of the material that eventually aggregates to form the Moon originates
from the impactor1, 4, 5. However, analysis of the terrestrial and lunar
isotopic compositions show them to be highly similar6, 7, 8, 9, 10, 11.
In contrast, the compositions of other Solar System bodies are
significantly different from those of the Earth and Moon12, 13, 14,
suggesting that different Solar System bodies have distinct
compositions. This challenges the giant impact scenario, because the
Moon-forming impactor must then also be thought to have a composition
different from that of the proto-Earth. Here we track the feeding zones
of growing planets in a suite of simulations of planetary accretion15,
to measure the composition of Moon-forming impactors. We find that
different planets formed in the same simulation have distinct
compositions, but the compositions of giant impactors are statistically
more similar to the planets they impact. A large fraction of
planet?impactor pairs have almost identical compositions. Thus, the
similarity in composition between the Earth and Moon could be a natural
consequence of a late giant impact.

Received on Wed 08 Apr 2015 06:09:56 PM PDT

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