Origin of Earth's neighbor, the mystery of the moon.

<P Align=center> </ P> <P> Moon is the Earth a rich mythology of the neighbors. .Although the United States in the 60s of this century, "Apollo" spacecraft on the moon, but the mystery about it is increasing, the biggest mystery is the origin of the moon. .</ P> <P> Usually, the origin of the moon there are several issues that must be considered. .Age: According to the study of isotopes of some elements, can confirm the age of the moon and Earth are similar, it is also about the formation of 4.6 billion years ago; quality issues: the quality of the moon about the Earth 1 / 81, the average density per cubic .3.34 g cm, roughly equivalent to the average density of the mantle, so the core of the moon can not be a big iron core; composition problem: the moon's chemical elements can all be found on Earth, but the aluminum contained in lunar rocks ., calcium and titanium and other chemical elements in rocks to be more than 6 times, while iron, sodium, magnesium rarely; orbit: more than nine planets satellite near the planet's equatorial plane to move, while the moon's orbit but with .Earth's equatorial plane is 120 degrees difference, but with close to the ecliptic plane. .</ P> <P> of these issues, As everyone mixed. .Thus the origin of the Moon is more difficult to get a satisfactory explanation. .At present, there are several claims: </ P> <P> First, the division said. .Only on grounds that the initial hump in the Earth's equator, the sun's gravity and Earth's rapid rotation under the action of the moon "fly" out, split into satellite. .But to reach the Earth's centrifugal force to throw the extent of the moon is impossible, but both have very different chemical composition. .</ P> <P> Second, the capture said. .The moon in the solar system that was originally the asteroid a general, in a chance in the near-Earth line when it was captured, and to become Earth's satellite. .But the orbit can not explain. .If the asteroid from the side after the ball, it only slightly to change its orbit, it is impossible to be captured over the Earth. .</ P> <P> Third, homologous said. .That both facilities from both a rapid transfer of the dust cloud generated action, but why do they have very different chemical composition of it? </ P> <P> above hypotheses have their own shortcomings, then, it was suggested that a .new hypothesis, that is violent asteroid hit the Earth, to take away a large material, and finally the formation of today's moon. .The impact to the Earth orbital plane tilted, and was hit out of the original material occupy the position of the Earth's equator. .Of course, this is just another hypothesis, there are many issues to be studied. .</ P> </ p>.