The mysterious dense layers of the Earth’s mantle could be the remnants of the collision of our planet with the protoplanet Theia 4.5 billion years ago.

The scientific community faced a huge mystery. Deep in the Earth’s mantle, about 2,900 kilometers away, two giant masses lie beneath West Africa and the Pacific Ocean. These are layers of rock that behave in a surprising way. When an earthquake occurs, the seismic waves slow down as they pass through these mysterious materials, suggesting that they are denser in composition than the rest of the Earth’s mantle. An international team of researchers has published a fascinating hypothesis: These masses, spanning thousands of miles, are the remains of another planet that Earth absorbed in a collision 4.5 billion years ago.

Chinese geologist Qian Yuan admitted it was a “crazy idea” when he presented it a few years ago at a virtual conference. Now his team has developed the idea and published it in Nature, and it’s not such a crazy idea anymore. “With the new evidence, I would say it is very likely,” Yuan told EL PAÍS.

The authors recall that fifty years ago, the theory that the Moon was formed as a result of a collision between the Earth and another young celestial body the size of Mars became popular. In this scenario, an embryonic planet called Thea or Theia collided with Earth. Computer simulations by Qian Yuan and his colleagues suggest that some of Thea’s molten mantle seeped into Earth’s primordial mantle and solidified, plunging and forming large anomalous seismic zones that are now intriguing scientists.

In Greek mythology, the deity Thea was the mother of Selene, the personification of the Moon.

The authors note that 8% of the Earth’s mantle consists of iron oxides, while the Moon has about 10%. The research team believes that Thea’s mantle was even richer in iron, which explains why it sank deep into the Earth’s core. Geophysicist Edward Garnero of Arizona State University was one of the scientists who responded with great interest to the “crazy idea” two years ago. “I think it’s perfectly viable until someone proves me wrong,” he said. Garnero is now a co-author of this new study with Qian Yuan of the Cal Institute of Technology.

doto Source: Dr. Ajay Kumar Singh, Dreamstime.com