A new study conducted by researchers at the University of California, Los Angeles has revealed that the moon was created by a head-on collision between Earth and a newly forming planet called Theia. While scientists already knew that this violent event, which took place approximately 100 million years after the formation of Earth, took place, it was believed to have occurred at an angle of 45 degrees or more, contrary to the current study that suggests a head-on collision.
The findings were based on the analysis of seven rocks obtained from the moon during the Apollo 12, 15 and 17 missions, as well as six volcanic rocks from the Earth's mantle. After analyzing the oxygen atoms of the rocks, the team was able to compare the isotopes of these atoms in the Earth and the moon's rocks.
"We don't see any difference between the Earth's and the moon's oxygen isotopes; they're indistinguishable," Edward Young, lead author of the study, said in a press release.
Young claims that the similarities between the oxygen in rocks on Earth and the moon points to a head-on collision - a side blow at an angle of 45 degrees or more, as previously believed- would have led to the moon being comprised mainly of the forming planet Theia, meaning different oxygen isotopes would be observed on the Earth and the moon.
"Theia was thoroughly mixed into both the Earth and the moon, and evenly dispersed between them," Young said. "This explains why we don't see a different signature of Theia in the moon versus the Earth."
Theia would likely have grown into a planet if the crash did not occur, according to Young.
The findings were published in the Jan. 29 issue of Science.