Remains of the ancient planet Theia may be buried in the Earth's interior: how they got there

The Earth's mantle may contain debris from a protoplanet called Theia that was swallowed up billions of years ago. This was probably due to a collision that led to the emergence of the Earth's satellite, the Moon.

This is stated in a study by scientists from the California Institute of Technology (USA). Their work is published in the journal Nature.

The most common theory of the Moon's origin is that billions of years ago, the planet Theia, which was the same size as Mars - about half the size of the Earth - crashed into the Earth. As a result of this collision, Theia was shattered into pieces.

Some of these fragments were absorbed by the young Earth, while other fragments ended up in the orbit of our planet and eventually formed a new celestial body, the Moon.

However, as scientists suggest, Theia may not have disappeared completely into the Earth's interior. Two fragments of its material may lie deep underground.

For decades, researchers have known that there are two large areas in the Earth's mantle that behave differently from the surrounding rocks. One of these areas is under Africa, and the other is under the Pacific Ocean.

Their difference becomes most obvious when scientists study how seismic waves travel through the mantle. In both areas, they slow down significantly. That is why these areas are called Large Low Velocity Shear Provinces or LLVPs.

Qian Yuan, who is one of the authors of the new study, suggests that there may be a connection between the death of Thea and LLVP. To confirm the guess, the scientists conducted a series of simulations of how the debris would have behaved after the collision with the Earth.

It turned out that rocks from Theia's mantle would have melted and fallen to the boundary between the mantle and the Earth's core, creating a thin layer that would have covered the entire core. However, over time, convection in the Earth's mantle would have slowly gathered this dense material into the two piles that scientists observe today.

Scientists can't get samples of this debris because of the depth at which it is located, but bubbles of hot material rise from these clumps and this, as Yuan notes, "may bring some chemical signals to the surface."

After analyzing the data, the researchers found that the chemical signatures are similar to those found on the Moon, but not typical of the Earth. Thus, as the scientists note, this confirms two theories at once: that LLVP (like the Moon) is the remnants of Theia, and that a giant interplanetary collision occurred.

"This giant impact that formed the Moon may be one of the most important factors in why Earth is so different from any other rocky planet we've found," Yuan said.

According to him, the ancient collision changed the atmosphere, crust, mantle, and also the core of our planet.

"So it was indeed probably the most important event in the history of the Earth," the scientist said.

He also suggested that if humanity seeks to find other planets that are similar to the Earth, it may be worth paying attention to those that have experienced similar giant collisions.

Earlier, OBOZ.UA also reported that scientists have discovered that the Earth's core has stopped and changed the direction of rotation.

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