Unlocking Earth’s Secrets: Scientists Unveil Ancient Planet Remains Deep Beneath Our Feet

Deep beneath the Earth’s surface, scientists have discovered two massive formations that might be remnants of a lost planet. These mysterious zones, located under Africa and the Pacific Ocean, have intrigued experts for years due to their unusual seismic behavior. Recent studies suggest these formations could be leftover debris from a planet called Theia, which collided with Earth billions of years ago, helping to create the Moon.

The structures, known as large low-velocity provinces (LLVPs), are found about 2,900 kilometers down, near the core-mantle boundary. Each spans thousands of kilometers and is believed to be roughly twice the size of the Moon. Researchers identified these formations using seismic imaging, which showed how they affect seismic waves traveling through the Earth.

What’s intriguing about the LLVPs is their density. They are 2 to 3.5 percent denser than the surrounding mantle, suggesting they formed differently from typical geological processes. A team from the California Institute of Technology (Caltech) led a study that proposes these structures might be composed of iron-rich fragments from Theia. One researcher called this idea “radical,” but it aligns well with the data observed.

The idea of a collision with Theia dates back about 4.5 billion years, during a time when Earth was still forming. While the Moon’s creation from the impact has been well-documented, what happened to Theia’s other material has remained largely a mystery. Geophysicist Qian Yuan began exploring this in 2019 after hearing about the giant-impact hypothesis. He led simulations with a multidisciplinary team to investigate how Theia’s mantle could have merged with Earth’s.

These simulations indicated that significant parts of Theia’s mantle could have settled into stable regions in Earth’s lower mantle. Since these regions are less affected by the energy of the collision, they could have preserved their distinct composition for billions of years.

The study highlights that the impact’s energy wasn’t evenly spread throughout Earth. The cooler, denser lower mantle likely absorbed the shock differently, which allowed heavy, iron-rich fragments of Theia to sink without fully mixing with Earth’s mantle. This could explain why LLVPs are found in specific locations rather than distributed evenly across the planet.

These structures aren’t just geological curiosities. If they are remnants of Theia, they could influence a range of processes on Earth, including mantle convection and plate tectonics. This could even extend to our planet’s magnetic field development.

The visual models from the research depict the two LLVPs as gigantic blobs clinging to the core-mantle boundary. One is situated beneath Africa, and the other beneath the Pacific Ocean, forming an extremely heavy mass below our feet.

Paul Asimow, a co-author of the study, underlined the significance of understanding these structures. Insights gained could also apply to other planetary bodies. For example, if similar impacts shaped Mars or Venus, their mantles might harbor remnants from their own violent pasts.

This research suggests that Earth’s inner structure has been molded by more than just internal dynamics; it also carries the legacy of a long-gone planet. As scientists continue to explore these ideas, the hidden formations beneath our feet serve as silent reminders of a dramatic cosmic history.

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