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"Perhaps it was the planet believed to have smashed into the earth causing the mantle and debris to coalesce into our moon?"

The theory that our Moon was captured has more credibility than that it simultaneously formed and orbited the Earth...though technically both ways are possible.

From what I heard as of late was that the earth was a molten planet already when it was smashed by another large planet. The resulting blow caused debris and mantle to go into space and eventually the earth came back together as a sphere and the smaller moon coalesced from the debris and gases around the earth after the collision. They claim this also explains why the moon was so much closer to earth in it's early years and slowly moves away.

The theory that our Moon was captured has more credibility than that it simultaneously formed and orbited the Earth...though technically both ways are possible.

Nope:

Ok, let us take a look at the Moon. :-)

1) How was it formed, 2) what is it made of, and 3) how far away is it are some of the questions that we can begin to answer.

1) How was the Moon formed?

There were at least five major ideas that were proposed as to the formation of the Moon.

Fission – The Moon split off from the Earth.
Capture – The Moon was captured by the gravity of the Earth.
Condensation – The Moon coalesced out of the same “stuff” the Earth did.
Colliding Planetesimals – Formed from colliding Planetesimals during the early formation of the solar system.
Collision – A body collided with the Earth causing a piece of the Earth’s crust to form the Moon from a resultant ring produced by that collision

The evidence points to the collision theory. 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. Second, throughout the solar system, the oxygen isotopes have been found to be different. If the Moon were captured, it too would not match the Earth’s oxygen isotope ratio (which it does). Fourth, by looking at the angular momentum and energy required, the theory that the Moon spun off the Earth after the Earth formed does not hold up.

This leaves us with the Collision theory as the best model we have for the formation of the Moon. The resultant collision caused a ring of debris from the Earths crust to form outside the Roche limit. If it had not, tidal forces would have not allowed for the Moon we see today.

A more in depth discussion of tidal locking since the Moon is tidal locked to the Earth. The reason the Moon keeps one face to the Earth (Its rotation on its axis matches the period of its orbit) is it is tidally locked to the Earth. Here is a more in depth explanation. The total angular momentum of the earth moon system, which is spin angular momentum plus the orbital angular momentum, is constant. (The Sun plays apart also) Friction of the oceans caused by the tides is causing the Earth to slow down a tiny bit each year. This is approximately two milliseconds per century causing the moon to recede by about 3.7 centimeters per year. As the Earth slows down, the Moon must recede to keep the total angular momentum a constant. In other words as the spin angular momentum of the earth decreases, the lunar orbital angular momentum must increase. Here is an interesting side note. The velocity of the moon will slow down as the orbit increases.

When the Days Were Shorter
Alaska Science Forum (Article #742) | November 11, 1985 | Larry Gedney
Posted on 10/04/2004 10:31:59 AM PDT by SunkenCiv
http://www.freerepublic.com/focus/f-chat/1234919/posts