Voilent head-on collision between Earth and Theia gave birth to Moon

Researchers have presented a new theory on how the closest celestial body to the earth, the moon came into existence. According to the scientists from the University of California, Los Angeles (UCLA), a violent head-on collision between earth and another forming planet named Theia gave birth to the moon.

Previously, scientists knew that Theia collided with the earth nearly 4.5 billion years ago. However, they thought that the collision was at an angle of 45 degrees. Now, scientists conducted a new study from the ground zero and established the fact that a head-on collision could only have given birth to the moon.

For the study, researchers analysed the chemical composition of seven lunar rocks brought by the Appolo 12,15 and 17 missions and then compared it with six volcanic rocks from the Earth’s mantle. Every rock has different oxygen composition. More than 99.9 percent of Earth’s rocks have 0-16 Oxygen atom means eight protons and eight neutrons. While the remaining isotopes of oxygen have either one or two extra neutrons (0-17 or 0-18).

Researchers knew that all the celestial bodies have different and unique ratios of oxygen isotopes. However, they were astonished to note that the moon and the earth have exactly the same composition as if they were one single body millions of years ago. Scientists used UCLA’s new highly advanced mass spectrometer for analysing the oxygen isotopes with ultra-high precision.

“We don’t see any difference between the Earth’s and the moon’s oxygen isotopes; they’re indistinguishable,” said Edward Young, lead author of the new study and a UCLA professor of geochemistry and cosmochemistry.

Scientists explained that such similar composition could only have been possible if Theia was thoroughly mixed into both the moon and the earth during the head-on collision. This might also be the reason behind why we don’t see a different signature of Theia in the moon versus the Earth.

This isn’t the first study that suggests a head-on collision of Theia and the earth. Previously, Matija Cuk, now a researcher with SETI Institute; Sarah Stewart, now a professor at UC Davis; and Robin Canup of the Southwest Research Institute, also proposed similar theory back in 2012. However, it is the first time that a team scientists have confirmed it with significant proofs.

The study appeared in the journal Science.

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