[SunkenCiv]

Thanks for the detailed response.

First, the Moon does not have an iron core. This pretty much rules out that it coalesced from the same cloud of debris that the Earth did.

:') That is evidence in support of capture. The apparent lack of an iron core -- the Earth's is 90 per cent iron, with about 10 per cent other stuff -- also suggests it wasn't born of the Earth, but obviously, either through an impact or an overspin one could suppose it would be made of core material. It would indicate a formation further out in the solar system.

If the Moon were captured, it too would not match the Earth’s oxygen isotope ratio...

There's no reason to expect it wouldn't -- the supposed impactor would contribute some (http://www.lpi.usra.edu/meetings/lpsc2000/pdf/1669.pdf assumes 50 per cent) of the lunar material, which means the supposed impactor must have had oxygen isotopes essentially identical to those of the Earth. It's simpler to say, there were two, not three. In addition, the lunar surface has been under bombardment continually for billions of years, and the oxygen isotope ratios of the incoming material must have had no contaminating effect at all.

The Moon is enriched in noble gases (http://presolar.wustl.edu/ref/LPSC2003_LunarSoils.pdf), and while the possibility exists that the presumed Oort Cloud has plenty and kicks comets laden with the stuff into the inner solar system, I'm aware of just two eyewitness accounts of lunar impact -- one from 1953 and the other from the 12th century. AFAIK, Apollo astronauts didn't visit either site.

The only origin theory currently outmoded seems to be the Condensation model, which was advocated by Roche. Otherwise, the math has been made to work for all of these scenarios.

But the Capture model is the only one which fits the fossil evidence. (':

George W. Bush will be reelected by a margin of at least ten per cent

[SunkenCiv]

http://www.FreeRepublic.com/forum/a3b7b414c3f78.htm#31
http://www.FreeRepublic.com/forum/a3b7b414c3f78.htm#34
http://www.FreeRepublic.com/forum/a3b7b414c3f78.htm#41

[SunkenCiv]

Just updating the ping list info.

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[SunkenCiv]

update.

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