During Earth’s development, it collided with a Mars-sized planet named Theia — the resulting debris formed not only Earth as we know it today, but the moon as well.
According to Discovery, Earth’s collision with Theia is something that scientists have posited before. The collision of the two planets would have taken place about 4.5 billion years ago and is believed to have occurred at an angle of about 45 degrees or more.
However, new research indicates that Earth might have crashed into Theia head on.
This changes what was once thought: research conducted at the University of California, Los Angeles has yielded data that suggests that, should Earth have collided with Theia at a 45 degree angle, Earth and the moon would have ended up with wildly different oxygen isotopes.
“We don’t see any difference between the Earth’s and the moon’s oxygen isotopes,” said Cosmochemistry and Geochemistry Professor Edward Young, lead author of the study. “They’re indistinguishable.”
Despite all this new data coming to light, the true nature of the planet Theia still eludes scientists. It is agreed that had Theia not crashed into Earth, it would have become an entire planet itself.
Disagreements arise, however, concerning the size of Theia. Some scientists contend that Theia would have been nearly the same size as Earth, while others insist that it was something more in line with the size of Mars.
While Theia itself is no longer a planet all on its own, large chunks of it now exist in the geological make-up of both the Earth and the Moon.
“Theia was thoroughly mixed into both the Earth and the moon,” said Young, saying the Theia’s “planetary embryo” was evenly divided between the Earth and the moon.