Fragments from another planet can hide in the earth

There is another planet in the earth. And it’s very big. In any case, this is theorized by a team of scientists from Arizona State University. But how could such an object get stuck there? It seems to have something to do with the moon.

According to the most popular current theory about the formation of our artificial satellite, a protoplanet called Theia – based on Titaness, the Greek mother goddess of the titans Helios and Selene – collided with the earth about 4 years ago, 5 billion years ago. The impact threw a giant stone into space and later shaped our moon.

Fragments from another planet in the earth’s mantle?

This theory, known as the giant impact hypothesis, arose in the 1970s after the Apollo missions showed that the composition of the lunar rocks was not significantly different from that of the rocks on Earth. Granted, this is just a guess like so many others about how the other planets in the solar system were formed. However, a new report claims that fragments of Theia could still be found in the mantle of our planet.

Layers the size of a continent

As we know from, this report was written by Qian Yuan, a graduate student at Arizona State University. It was recently presented at the 52nd Lunar and Planetary Science Conference. Yuan and his colleagues believe the remains of Theia are buried up to 1,000 km under the mantle of the blue planet between West Africa and the Pacific.

Fragments of Théia are buried up to 1000 km below the earth’s mantle. Photo credit: Shutterstock / Pavel Gabzdyl

These plates, known in French as “LLSVP” (for provinces with high shear rates) or large provinces with low shear rates, therefore extend over several thousand kilometers. Researchers know they’re there because seismic waves from earthquakes abruptly slow down as they pass, suggesting that the layers are denser and chemically different from the surrounding mantle rock.

A size comparable to the earth?

Giant impact theory suggests an impactor the size of Mars, but Yuan and colleagues, including astrophysicist Steven Desch, suggest Theia was comparable in size to Earth. According to this new hypothesis, after the two planets collided, lighter stones were thrown into space and eventually formed the moon, while heavy material remained buried near the Earth’s core.

For now, this is all theory, but future lunar missions should allow samples of the lunar mantle to be compared to LLSVPs, which could ultimately prove the correctness of the hypothesis by Yuan and his collaborators.