Study Suggests an Alien World May Be Concealed Within Earth.

Key Takeaways:

1. Earth may contain remnants of Theia, a Mars-sized planet that collided with Earth long ago.
2. This collision is believed to have also created the Moon, with parts of Theia still within Earth’s mantle.
3. The dense areas, or LLSVPs, under West Africa and the Pacific could be intact remnants of Theia.
4. Arizona State researchers modeled how Theia’s materials sank to Earth’s lower mantle, forming dense zones.
5. Theia’s materials may persist in Earth’s mantle due to their high density, staying out of mantle convection.

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Planetary remnants from Theia’s impact may still rest in Earth’s mantle, spanning “continent-sized” regions.

Evidence of an Ancient Collision Within Earth’s Mantle

New research proposes that dense zones deep within Earth’s mantle could be remnants of a massive planetary collision with an ancient Mars-sized body named Theia. This impact, believed to have occurred around 4.5 billion years ago, is also theorized to have given rise to the Moon. Scientists, however, have now focused on studying dense regions within Earth’s mantle, thought to be large portions of Theia that stayed intact after the impact, offering new insights into Earth’s structure and origin.

In 2016, researchers at UCLA suggested Earth and Theia may have fused after colliding, creating one larger planet. Until now, scientists speculated that Theia’s materials merged uniformly with Earth’s. But Arizona State University researchers, led by Qian Yuan, recently presented a new hypothesis at the 52nd Lunar and Planetary Science Conference. They propose that two dense structures deep within Earth, known as Large Low Shear Velocity Provinces (LLSVPs), could be intact portions of Theia’s mantle. These LLSVPs, located under West Africa and the Pacific Ocean, are notably “continent-sized” and possibly remain in their original state due to their higher density.

The Formation and Persistence of Theia’s Mantle in Earth

Using advanced modeling, Yuan’s team found that Theia’s materials, initially denser than Earth’s, could have sunk after the impact and gathered in isolated regions in the lower mantle, forming dense, thermochemical piles. Their simulations revealed that these regions would occupy between 3-15% of the Earth’s lower mantle, matching the distribution of the present-day LLSVPs. This finding could clarify why these massive sections are distinct in density and structure from other parts of the mantle.

Yuan explained that Earth’s mantle operates through a process known as convection, where materials circulate at specific temperatures and densities. Theia’s remnants are dense enough to avoid being pulled back into the convection zone, allowing them to remain trapped deep within the mantle for billions of years. This process may explain why Earth’s internal structure remains non-uniform, containing significant remnants of Theia still intact. Yuan’s comparison between the size of LLSVPs and the mantle of Mars suggested a striking similarity, supporting the theory that Theia was Mars-like in size and composition.

Implications and Future Insights

This research brings fascinating implications for planetary science, particularly the Moon’s formation, as both Earth and the Moon could share materials from Theia. Studying the Moon’s surface composition alongside these dense mantle regions could yield valuable insights into Earth’s early formation and the aftermath of ancient cosmic collisions. This link between the Moon and the LLSVPs represents a rare chance to analyze planetary materials from two vastly different parts of the Earth-Moon system, stretching Earth science research possibilities.

While this study is in early stages, it emphasizes the potential of understanding Earth’s deep interior through the lens of ancient planetary interactions. The Arizona State University team hopes their model will help answer other longstanding questions about Earth’s structure and formation. Further investigations into LLSVPs could reveal even more about the materials and forces that shaped the planet billions of years ago, advancing both geology and planetary science.