Moon Derives From Earth, Space Object, Study Says: Nat' Geographic.com

[Ivan Seeking]

"Science has a better understanding of how and when the moon came to be thanks to a team of German geochemists who compared ratios of trace elements in rocks from the Earth, the moon, Mars, and meteorites."

http://news.nationalgeographic.com/news/2003/08/0811_030811_earthmoon.html

[I, Brian]

It's a theory that's been gaining ground for some time. I think the Apollo missions essentially first addressed it, so it's not a new theory.

However, I'm sure New Scientist mentioned not long ago something about a great disparity of certain isotope distributions across the earth, the moon, mars, and different forms of meteorite. You can be assured that this entire issue has not yet been satisfactorily addressed.