Continental remnants of an extraterrestrial world could be buried deep in Earth

A Mars-sized planet that collided with Earth in its infancy may have left two gigantic portions of itself at the heart of Earth, scientists have theorized in a new study.

According to a team led by Qian Yuan, a geodynamics researcher at Arizona State University, the extinct planet known as Theia not only integrated part of itself inside the Earth, but probably also helped form the moon. The team presented a paper detailing the theory earlier this month at the 52nd Lunar and Planetary Science Conference 2021.

Based on geodynamic models and isotopic evidence, scientists believe that two mysterious dense areas 1,000 miles below the Earth’s surface are actually “material remnants of Theia’s mantle.” The dense areas – hundreds of kilometers high and thousands of kilometers wide – lie beneath West Africa and the Pacific Ocean.

Yuan began his quest after studying the “giant impact hypothesis” regarding the formation of the Earth’s moon. The theory, supported by the composition of moon rocks, holds that the moon was formed from fusion debris created by Theia’s massive crash on Earth 4.5 billion years ago.

A study funded by NASA in 2016 postulated that Earth could in fact be two planets – itself and Theia – that merged when they collided.

“Theia was completely mixed with both the Earth and the moon, and evenly dispersed between them,” lead author Edward Young, a professor at the University of California, Los Angeles, said in a statement to the time.

But Yuan believes his team have now located the actual parts of Theia inside Earth, which are the largest formations in Earth’s interior.

“You could say these are the biggest and the biggest meteorites if they are mainly Theia’s mantle,” Yuan told Vice. “It’s really cool.”

For years, scientists have discussed the possibility of a link between the mysterious dense areas and Theia, Science magazine reported. But Arizona State University professor and seismologist Edward Garnero said Yuan’s work was the first time anyone had mobilized multiple sources of evidence to build a serious case for it.

“I think it’s completely viable until someone tells me it’s not,” Garnero said.

Check out Yuan’s speech here: