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Originally Posted by mikesouth
No thats actually the current best theory based on the orbit, the makeup of lunar soil etc. The old theory. the one I was taught for instance is that the moon was captured, as most moons are. The collision theory successful explains the EXACT orbit the moon is in as well as the fact that it is getting farther and farther from earth.
Archeological evidence here on earth also support the collision theory in that the tidal patterns completely align with the the predicted position of the moon, the length of the days back then (they were quite a bit shorter) and other evidence. The collision theory is, in fact pretty solid.lots to support it no real science that doesn't.
If you really want to learn about here is NASAs explanation which is actually pretty understandable
NASA scientist Jen Heldmann describes how the Earthâ??s moon was formed | Solar System Exploration Research Virtual Institute |
In comparing titanium isotopes from both the moon and the Earth, the match is too close to support the theory that the moon could have been made partly of material from another planet. (some other planetary body crashing into the earth, and the debris combining to form the moon).
Up to about 2,900 kilometers (1,800 miles) into the Earth (not quite half way to the center), is what we know as the mantle and crust. They are predominantly formed of silicate, a compound mad of silicon, oxygen, and other elements. Past the halfway mark is a dense metallic iron material that makes up the Earth?s core.
It's been found that the heavier isotopes from silicate samples taken from the Earth consisted of increased amounts of the heavier isotopes of silicon. Mars, the asteroid Vesta, and various chrondites (primitive meteorites that never produced ainner cores) do not contain such an arrangement, even though they have an iron core. is much smaller than the Earth (about one-eighth the size), so did not have enough mass to generate the pressure necessary to form the same core as found in the Earth.
On the other hand, the Moon does show a similar composition of the silicon isotopic composition as the Earth. However, it, too, is much smaller than the Earth?about one-fiftieth as large as the Earth and about one percent of the Earth?s mass?making it even less likely to have been able to generate enough pressure to form an Earth-like iron core.
However, such a core does exist at the center of the Moon, but no one can explain how it got there.
Most scientists agree that if a planet had smacked into Earth and the moon came about as a result, than the moon ought to be made of some of that other planet as well. Some say the laws of physics suggest it would be somewhere in the neighborhood of forty percent. If that?s the case, why don?t studies of rocks brought back by the Apollo missions show any evidence of this other planet?