New studies prove that the moon formed in a planetary collision
One of the most accepted theories regarding the formation of the Moon says that the natural satellite was created from pieces that went flying after a catastrophic collision between two Planets 4,500 million years ago.
New studies help explain the doubts that remain pending in this theory of the “giant impact”. The theory is that the moon would have formed of pieces of a mysterious planet (sometimes called “Tea” for the Greek goddess mother of Selene, the Moon) that have a similar size of Mars, which had collided with the Earth, which was in process of formation.
This theory has a problem: Scientists know that the Earth and Moon are made virtually the same material – the moon is not made exclusively of the remains of another planet.
One study, by Matija Cuk of the SETI (Search for Extraterrestrial Intelligence) Institute and Sarah Steward of Harvard, suggests that the key is in the rotation of the Earth. If our planet had had a very fast rotation (three hours a day or so), then the impact could have been able to fire enough material to form the Moon. This speed may sound implausible, however, the researchers note that initially, the solar system gave off things all the time, and that the impacts could have caused the planets achieved high speeds.
The study appeared in the journal Science, and also explains how the Earth slowed to a normal rate over time. The gravitational interaction between the Earth’s orbit arround the Sun and the orbit of the Moon around the Earth could have stopped rotating, causing the 24-hour day that we have today.
Two large planets
A second study, also published in Science, suggests that the planet that crashed was not the size of Mars, but that was the same size as ours. In this case, each contain two planets 50% of the mass of the earth.
Our planet would have absorbed some of Tea after the crash, and then it flew off to the moon would have formed. Thus, the material of both being almost identical. The research of Robin Canup of the Southwest Research Institute, also implies an increase in the speed of rotation of the Earth after the impact, however, with the above explanation of Cuk and Steward can understand how the Earth could slow.
A third study, published in the journal Nature , said that the moon rocks, but are chemically similar to those on Earth, they have much less volatile elements (that evaporate easily). A giant impact would explain why these elements are not present.
The collision would have released so much energy that Theia melted and vaporized and much of the Earth’s mantle. Then the moon was condensed from the vapor cloud of rocks, and some of it was re-attached to the Earth.
– Huge Moon-Forming Collision Theory Gets New Spin (Space)
– New Study Proves Moon was created in massive planetary collision (PhysOrg)