During the process of formation of the Universe, space objects collided left and right. One of them had a surface of fire bubbling and collided with Theia, who was coming at breakneck speed. The result of this shock was a huge incandescent and silent explosion, causing an eruption of diamond material into space. In the end, our planet and Selene (the Moon) appeared.
This creation story, which is 4.5 billion years old, is not a myth, as far as scientists know. Shortly after our Sun formed and the planets formed, an object similar in size to Mars (half the size of our planet) collided with the cooling Earth.
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The collision launched matter, especially from Earth, into space, as the colliding object was practically vaporized. The debris entered Earth's orbit and, after millions of years, joined our planet.
Image: Rodrigo Mozelli/Olhar Digital
Did Theia form Earth's Moon?
According to Atlas Obscura, scientists call the object that collided with Earth Theia; In Greek mythology, Theia is a goddess, mother of Selene, who, in turn, is known, in Roman mythology, as Luna, the goddess of the Moon; None of this is a coincidence: astronomers were based on observed fragments.
The lunar rocks have a similar chemical signature to several volcanic rocks on Earth, indicating that they may have shared their origins. The radioactive matter found in such rocks acts as a kind of timer, which began to tick as soon as the rocks were formed. Furthermore, it shows that the Moon emerged shortly after the Earth.
And, through computer simulations, it was demonstrated that it is possible to form the Moon as we know it today from the launch of a projectile the size of the Red Planet against an Earth completely covered in magma.
But there is one question: what happened to the object that would have created the Moon, Theia? To prove the theory, it would be necessary to find some remnant of it, as parts of Theia would be so mixed with those of the Moon that, chemically, it is impossible to find them.
Is Theia on Earth?
At the edges of the Earth's core, there are two giant bubbles. They are located below Africa and the Pacific, respectively.
No one knows for sure what they are, but the seismic waves that cross the planet deeply reveal that they are real and their size is expanding: continental, something around 30% of the core-mantle boundary. But its chemistry, nature and provenance have remained unknown since they were discovered decades ago.
Naturally, some scientists have even wondered: could these two bubbles be remnants of Theia?
To leave us with our jaws dropped, a study published in 2023 in Nature showed that this could actually be real. This is because state-of-the-art computer simulations showed the supposed collision.
In these simulations, Theia's extreme crust would have been destroyed by the impact, but its molten, mass-like mantle below would have remained partially intact and some of it could have fallen to Earth, covered in magma.
As the fragments are rich in iron and therefore very dense, they would have sunk a lot and settled into the newly formed iron core, remaining there to this day.
Of course, this is circumstantial evidence, as it is impossible to extract unaltered pieces of the Earth from such depth, in order to confirm the assumption.
However, this study aligns with several other clues that suggest that Theia helped form Earth and that some of it found its way onto our planet.
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Bubbles beneath the Earth are active!
The bubbles suspected to be remains of Theia are not passive. This is because the heat from the Earth's core-mantle boundary would be causing some agitation within them, causing the emergence of superheated matter.
Over millions of years, some of these plumes reach the base of tectonic plates, boiling a lot of magma and fueling volcanic eruptions around the world, including those that dump lava into the ocean.
