How was the moon formed?

Hello everyone and welcome to my first official post of my new astronomy blog, I am hoping I can make this as intresting as I possibly can, and since I am just a novice in astronomy none of which I post should be over anyones head.

The first question I am going to try and cover is how was the moon was created. Currently there are four theroies that astronomers today are kicking around, these four are the capture theory, the cocreation theory, the collision-ejection theory and the last being the fission theory.

The fission theory holds that the Moon was pulled out from a rapidly rotating proto-Earth. This theory does not explain why the Moon has birtually no water incorporated in its rocks, as revealed by the bone-dry samples brouht back by Appollo astronauts. A simple way of stating this is that as the newly formed Earth was rotating at a much faster speed than it does today a blob of material seperated from Earth and became the moon, however if this theory was true there would be traces of water in the rock samples taken from the Moon and not a trace of water has ever been found.

The Capture theory says that the Moon was formed elsewhere in the solar system and then was drawn into orbit about the Earthby gravitatioal forces. However, it is physically very difficult for a planet to capture a large moon. Furthermore, because bodies formed in differnt places have different overall chemical compositions, this theory fails to explain the similar geochemistries of the Moon and the Earth's surfaces.

The cocreation theory proposes that the Earth and the Moon were formed near each other at the same time. However, this theory fails to explain why, compared to the Earth, the Moon has less of the denser elements, such as iron, and why certain types of rocks found on the Moon are not found on Earth.

The fourth theory, now held to be correct by most astronomer is the collision-ejection theory, or large impact theory, it proposes that the newly formed Earth was struck at an angle by a Mars-sized astroid that literally splashed some of the Earth's surface layers into orbitaround the young planet. Evidence from Moon rocks places this event at around 4.5 billion years ago, whithin the first 100 million years of the Earth's existance.

The collision-ejection theory is consistent with many of the known facts about the Moon. For example, rock vaporized by the impact would have been depleted of volatile (easily evaporated) elements and water, leaving the Moon rocks parched, as we know they are. Also, the Moon has very little heavy iron-rich matter because the mateerial had sunk deep into the Earth before the asteroid struck. The material from the Earth that splashed ito orbit and formed the Moon was mostly the lighter rock floating on the Earth's surface. Furthermore, most of the debris from the collision would orbit near the plane of the ecliptic as long as the orbit of the impacting asteroid had been near that plane. Also, the impact of an object large enough to create the Moon could have tipped the Earth's axis of rotation and so inaugurated the seasons we experince today.

I hope any of you (if anyone) who have read this learned something from it, I myself find astronomy very intersting. If you have any questions you would like me to explore please don't hesitate to ask.