The first mystery revolves around the formation of the moon, which is most commonly theorized to have resulted from a collision with Earth when it was in its formative phase about 4.5 billion years ago.
The impact of this collision with Theia, an ancient planet roughly the size of Mars, resulted in the dispersion of enough material into space to form the moon.
The remaining challenge is to find traces of Theia, not in the atmosphere, but beneath the Earth, according to a study published by a team of American scientists in the journal “Nature.”
These two masses, each roughly the size of a continent and located in the lower mantle of the Earth, separate the Earth‘s core from its crust beneath Africa and the Pacific Ocean.
These masses are hotter and denser than their surroundings. Computer simulations conducted by researchers suggest that these two masses are “buried remnants” of the planet Theia that penetrated Earth during the collision.
Chen Yuan, a geodynamics researcher at the California Institute of Technology (CalTech) and the lead author of the study, said in an interview with the French news agency that this collision was “the most violent event in Earth‘s history.”
He considered it “very strange” that there are no visible traces of it. What prompted him to think about this was the question of the location of the colliding body. He said, “My answer: under the Earth.”
Between Space and Geology
The research led to the collaboration of experts from two very different fields, space and geology.
These molten rock fragments, with sizes spanning tens of kilometers, cooled and solidified and descended to the Earth’s lower mantle and its core, aided by the presence of a higher proportion of iron oxide than the Earth’s surface environment, making them heavier.
These rock fragments accumulated into two different masses, each larger than the moon, according to Yuan, who emphasizes that these conclusions are the result of incomplete models and simulations.
Christian Schroeder, an Earth sciences and planetary exploration expert at the University of Sterling in Scotland, told Agence France-Presse that Yuan’s theory “aligns with many indicators.”
Schroeder, who was not involved in the study, saw the theory proposed by Yuan as “significant.”
While this result may not provide a clear answer to the origin of the moon, it offers a “credible explanation for the strange cases observed at the boundaries between the Earth‘s mantle and core,” according to Schroeder.
As for the remnants of Theia, they may be “responsible for important processes occurring on Earth,” according to the expert.