The moon was formed by a violent impact produced by the collision between a proto-planet called Theia and the early Earth approximately 100 million years after the Earth formed. This is the conclusion of a new study performed by UCLA geochemists.
Previous research suggested that the newborn Earth was hit by a Mars size forming planet named Theia. New evidence claims that the rocks that became Earth and the moon were mixed together before they separated. This high-energy impact due to collision between the two planets formed the moon, according to study lead author Edward Young, a geochemist and cosmochemist at the University of California, Los Angeles.
This high-speed crash occurred approximately 4.5 billion years ago. Scientists used to think that Earth collided with Theia at an angle of 45 degrees or more. However, the new study found evidence that suggests a head-on collision, according to the website Space.
According to the website Science20, a head-on collision was initially proposed in the year 2012 by Robin Canup of the Southwest Research Institute and separately during the same year by Sarah Stewart, now a professor at UC Davis.
In order to come to this conclusion, scientists analyzed volcanic rocks from the Earth's mantle and moon rocks brought to the Earth the Apollo missions. The research team found a chemical signature left by the giant impact in the rocks' oxygen atoms.
The scientists used state-of-the-art technology in order to make very accurate measurements. According to Professor Young, the study could not find any difference between moon's and Earth's oxygen isotopes.
The fact that oxygen in rocks on our moon and on the Earth shares the same chemical signatures proves that Earth and Theia collided in a head-on impact. Theia was mixes into both the moon and the Earth, according to Young.
The forming planet did not survive the collision and was dispersed evenly between the Earth and moon. Most of the scientists believe that the proto-planet Theia was approximately the same size as the Earth.
