A group of scientists presented a new theory that may solve two mysteries, one of which relates to an object that orbits the planet Earth every day, and the other that may be present in its interior.
The first mystery is the formation of the Moon, which the most common theory indicates is that it was formed after a forming planet collided with the Earth 4.5 billion years ago.
The collision with Theia, an ancient planet the size of Mars, spread enough material into space to form the Moon.
The question of finding the remains of “Theia” remains by looking not in the air but under the ground, according to the study published by a team of scientists from American institutions in the journal “Nature”.
At a depth of 2,900 kilometers below the Earth’s surface, two large points have aroused the interest of scientists since they were discovered using seismic waves in the 1980s. These two masses, each of which has a size similar to the area of a continent, are located at the bottom of the Earth’s mantle, which is the layer that separates the Earth’s core from its crust, under Africa and the Pacific Ocean.
The two masses are hotter and denser than the place surrounding them. Computer simulations conducted by researchers indicate that these two masses are “buried traces” of the planet “Theia” that penetrated the Earth at the time of the collision.
Qian Yuan, a geodynamics researcher at the California Institute of Technology (CalTech) and the lead author of the study, said in an interview with Agence France-Presse that this collision was “the most violent event the Earth has ever been exposed to” in its history.
He considered it “very strange” that there was no visible trace of this. What prompted him to think about the subject was his question about the location of the impact body. He said: “My answer: underground.”
The research led to the cooperation of experts from two very different specializations: space and geology, and the planet “Theia” collided with the Earth during its formation at a speed of more than 36 thousand kilometers per hour, a speed sufficient to cause part of the body to penetrate “the Earth at a great depth to reach its lower mantle.”
These molten pieces of rock, which were several tens of kilometers in size, cooled, froze, and descended to the boundaries of the Earth’s mantle and core, and this was helped by the presence of a greater percentage of iron oxide than that found in the terrestrial environment, which made them heavier.
These pieces of rock accumulated into two different masses, each larger than the size of the moon, according to Yuan, who stresses that these conclusions remain the result of perhaps incomplete models and simulations.
Christian Schroeder, an expert in Earth sciences and planetary exploration at the University of Stirling in Scotland, told Agence France-Presse that the theory proposed by Yuan “is consistent with many indicators.” Schroeder, who did not participate in the study, said that “what was reached is an important result.” Even if this result does not provide a clear answer to the question of the origin of the Moon, it provides “a reliable explanation for the strange cases observed at the border between the Earth’s mantle and its core,” according to Schroeder.
As for the remains of “Theia,” it may be “responsible for important processes taking place on Earth,” according to the expert.
• At a depth of 2,900 kilometers below the Earth’s surface, two large points have aroused the interest of scientists since their discovery.
