Earth’s Moon was born from Violent Collision between Early Earth and Forming Planet

Earth’s Moon was born from Violent Collision between Early Earth and Forming Planet

As per a new report by the UCLA geochemists and colleagues, the moon was formed by a violent, head-on collision between the early Earth and a ‘planetary embryo’ called Theia. It is not something new, scientists had already been aware about this high-speed crash, which occurred almost 4.5 billion years ago, but many thought the Earth collided with Theia at an angle of 45 degrees or more. New evidence reported Jan. 29 in the journal Science substantially strengthens the case for a head-on assault.

Researchers have analyzed seven rocks brought to the Earth from the moon by the Apollo 12, 15 and 17 missions, as well as six volcanic rocks from the Earth's mantle, five from Hawaii and one from Arizona. The team of researchers used state-of-the-art technology and techniques to make extraordinarily precise and careful measurements. They verified them with UCLA's new mass spectrometer. More than 99.9% of Earth's oxygen is O-16, so called because each atom contains eight protons and eight neutrons. But there also are small quantities of heavier oxygen isotopes: O-17, which has one extra neutron, and O-18, which have two extra neutrons. Earth, Mars and other planetary bodies in our solar system each has a unique ratio of O-17 to O-16—each one a distinctive ‘fingerprint’.

In 2014, a team of German scientists reported in Science that the moon also has its own unique ratio of oxygen isotopes, different from Earth's. Edward Young, lead author of the new study and a UCLA professor of geochemistry and cosmochemistry, said the isotopes between Earth and the moon’s oxygen is indistinguishable. Young said that it seems surprising to see that oxygen in rocks on the Earth and our moon share chemical signature. Researchers said that a head-on collision, however, likely would have resulted in similar chemical composition of both Earth and the moon.

Young said that Theia was thoroughly mixed into both the Earth and the moon, and evenly dispersed between them, which explain why we don't see a different signature of Theia in the moon versus the Earth.