Re: Moon

There is a very good article on the current thinking of the Moon's formation in the July, 1994 issue of "Scientific American."

Basically, the current belief is that the Moon formed when a Mars-sized object hit the young Earth. Computer simulations find that, if the object hit at a glancing angle, a large amount of material would be flung into orbit around the Earth. Dense, metallic material would preferentially be pulled back onto the Earth, while much of the lighter material would eventually coagulate to form the Moon. This would explain why the Moon chemically resembles the mantle of the Earth (the region of the Earth just below the crust), and has much less iron than the Earth.

Another good source of information on the Moon's formation is a Web site called The Nine Planets.