The collision that created the moon could also have brought water to the beginning of the Earth

Scientists from the University of Munster discovered that the Earth had its waters after a collision with Theia. Theia was the ancient body that collided with the Earth and formed the Moon. Their discovery shows that the water of the Earth is much older than previously thought.

The permanent theory of the formation of the Moon involves an ancient body called Theia. About 4.4 billion years ago, Theia collided with Earth. The collision created a massive debris ring and the Moon formed from this debris.

According to the theory of the statutes, the Earth has collected its waters over time, after the collision with Theia, with comets and asteroids providing water. But the new study from the University of Munster presents evidence of another source of water from the Earth: Theia herself.

"Our approach is unique because, for the first time, it allows us to associate the origin of water on Earth with the formation of the moon."

Thorsten Kleine, professor of planetology at the University of Münster.

Scientists have long thought that Theia was a body of the inner solar system, since it was rocky in nature. But the new study says that is not the case. Instead, Theia has its origins in the external solar system.

The key to understanding these events is the idea of ​​the dry and wet parts of our solar system. The solar system was formed about 4.5 billion years ago and we know that its structure has led to a dry interior region and a humid outer region. The Earth is a bit of a mystery because it was formed in the dry region, closer to the Sun, but it has an abundance of water. So studies like this one, trying to understand how the Earth got its water, are important.

Our understanding of the Earth's water comes largely from two types of meteorites: carbon-rich meteorites, which are rich in water, and non-carbon meteorites, which are drier. And the carbon meteorites come from the outer solar system, while the drier carbonless meteorites come from the inner solar system. Do you have all this?

There is ample evidence that the Earth's water has been supplied by the humid carbonaceous meteorites of the outer solar system, but when and how it happened, it was never certain. This study brings some certainty to the question.

"We used molybdenum isotopes to answer that question."

Gerrit Budde, lead author, Institute of Planetology in Munster.

The study is called "molybdenum isotopic evidence of late accumulation of outer solar system materials on Earth" and is published in the journal Nature Astronomy. As the title makes clear, these are essentially the isotopes of molybdenum and the difference between molybdenum in the Earth's core and molybdenum in the Earth's mantle.

"We used molybdenum isotopes to answer that question. The isotopes of molybdenum allow us to clearly distinguish between carbonaceous and non-carbonaceous materials and as such represent a "genetic fingerprint" of materials from the external and internal solar system, "says Dr. Gerrit Budde of the Institute of Planetology. in Münster and lead author of the study.

Why molybdenum? Because it has a very useful property to answer the question of the origin of the water of the Earth. Molybdenum is very favorable to iron, which means that it is largely located in the heart of the Earth, which is largely made of iron.

The nucleus is old because the Earth was a molten ball in its infancy and heavier elements like iron migrated to form the nucleus. Since molybdenum likes iron, molybdenum goes to heart too. But there is also molybdenum in the earth's crust, which must have been delivered to the Earth after cooling, otherwise it would have migrated to the nucleus. So, the Earth has two populations of molybdenum, and each of them is a different isotope.

And this late molybdenum in the Earth's mantle must come from bodies that crashed later on the Earth during its formation. "Molybdenum, which is accessible today in the Earth's mantle, is therefore coming from the last stages of its formation, whereas the molybdenum of the earlier phases is entirely at the heart," says Dr. Christoph Burkhardt, the second author of the study.

These results clearly show, for the first time, that carbonaceous materials from the humid outer zone of the solar system arrived late on Earth.

But the paper goes further than that. Since the molybdenum in the mantle had to come from the external solar system because it was a different isotope, it means that Theia also had to come from the external solar system. The scientists behind this research show that the collision with Theia provided enough carbonaceous material to account for most of the Earth's water.

"Our approach is unique because, for the first time, it allows us to associate the origin of water on Earth with the formation of the moon. To put it simply, without the moon, there would probably be no life on Earth, "says Thorsten Kleine, professor of planetology at the University of Münster.