Theia's Impact. Unveiling earth's ancient connection to moon's birth

02.11.2023 posted by Admin

Revealing the origins. Earth's collision birthed the moon

New research has uncovered an intriguing connection between Earth and the moon's creation. It appears that the formation of the moon can be attributed to the collision between Earth and a protoplanet. This collision, which happened when Earth was still in its infancy, may have left massive fragments of the protoplanet near the Earth's core, potentially the size of continents.

Around 4.5 billion years ago, Earth came into existence, and not long after, the moon made its appearance. The prevailing theory regarding the moon's origin suggests that it was born from a colossal collision between two protoplanets, or early-stage planets. One of these protoplanets was Earth itself, while the other was a Mars-sized rock known as Theia, named after the mother of the moon in Greek mythology.

This concept, often referred to as the "giant impact hypothesis," postulates that the moon formed from the debris generated by this monumental collision. However, direct evidence of Theia's existence has remained elusive. Nonetheless, new research suggests that remnants of Theia may have been hidden deep within Earth's mantle, close to the planet's core, leaving a lasting impact on Earth's development.

Qian Yuan, the lead author of the study and a geodynamicist at the California Institute of Technology, explained that their work indicates this enormous collision had a profound and enduring influence on Earth's evolution, possibly explaining why Earth displays distinct geological features compared to other rocky planets.

In their recent investigation, Yuan and his team explored two extensive rock formations in Earth's lowermost mantle, located approximately 1,800 miles beneath the planet's surface. Previous studies had observed seismic waves moving more slowly through these anomalies, suggesting they had greater density and differed in composition compared to the surrounding mantle.

Through computer simulations, the research team suggested that a portion of Theia's mantle might have become integrated into Earth's lower mantle. This Theia-derived rock would have been between 2 to 3.5 percent denser than Earth's own mantle, based on lunar data and previous Theia models.

The computer models indicated that these dense Theia remnants could have been tens of miles in diameter. Over time, this molten rock would have settled and solidified, forming dense structures atop Earth's core, collectively weighing about one-fortieth to one-sixtieth of Earth's total mass.

These new findings propose that these structures would have a higher iron content compared to Earth's typical mantle rock and could share a similar chemical composition with lunar volcanic rocks.

It is possible that traces of these remnants could be brought to the Earth's surface through mantle plumes. Mantle plumes are columnar, mushroom-shaped formations of superheated rock that ascend from the vicinity of Earth's core. Prior research has suggested that regions such as Iceland and island chains like Hawaii and the Galapagos were created as tectonic plates drifted slowly over mantle plumes, causing intense heating of the overlying material.

Yuan's current investigations aim to determine whether these two deep mantle structures may have played a role in stimulating the unique geological activities on Earth. The Earth's surface consists of large tectonic plates, and the movement of these plates, known as plate tectonics, is responsible for events such as earthquakes, volcanoes, the formation of mountain ranges and islands, and the release of essential elements from rocks. The most significant driving force behind plate tectonics is subduction, which occurs when one plate is pushed beneath another. Earth is the only known planet where subduction is observed, and Yuan is exploring whether these deep mantle structures could be connected to this phenomenon.

These groundbreaking findings were published on November 1 in the journal Nature.
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