Life exists on Earth thanks to two things: water and the moon. Without both of these, it's likely that life would not have developed on the planet.
Now, new research from the University of Münster in Germany reveals that the origins of these two are inextricably linked. It turns out that a single crash gave birth to both the moon and water on Earth.
The Collision That Started It All
Roughly 4.4 billion years ago, a cosmic Mars-sized object known as Theia crashed into Earth and triggered the formation of the moon.
Scientists used to believe that Theia originated nearby in the inner solar system. However, findings of a new study published in the journal Nature Astronomy revealed that it actually came from the outer solar system and carried massive amounts of water to Earth.
When the solar system formed about 4.5 billion years ago, it was arranged in such a way with dry materials coming from the inner solar system and wet "carbonaceous" materials from the outer solar system. Since Earth formed in the dry inner region, it's quite surprising that water exists on the planet.
Previous research has indicated that carbonaceous materials likely brought water to Earth, but it's unknown when and how this occurred. To solve the mystery, the research team from Münster used molybdenum isotopes, according to a news release.
"The molybdenum isotopes allow us to clearly distinguish carbonaceous and non-carbonaceous material, and as such represent a 'genetic fingerprint' of material from the outer and inner solar system," explained lead author Dr. Gerrit Budde of the Institute of Planetology in Münster.
New Insights On Earth's Formation
Findings showed that Earth's molybdenum isotopic composition is between the composition of carbonaceous and non-carbonaceous meteorites, which suggests that some of Earth's molybdenum came from the outer solar system.
Second author Dr. Christoph Burkhardt explained that molybdenum from the earlier stages of Earth's formation is located in the planet's core, while the molybdenum in the mantle is from the later stages. The study showed that the carbonaceous material from the outer regions of the solar system became part of Earth late.
Additionally, most of the molybdenum in the mantle actually originated from the protoplanet Theia. Since a huge chunk of the molybdenum in the mantle also comes from the outer solar system, which suggests that Theia also came from the outer solar system.
The epic smash-up between Earth and Theia not only gave birth to the moon, but the protoplanet also delivered enough carbonaceous material to Earth to give it its entire water supply.
"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," explained Thorsten Kleine from the University of Münster. "To put it simply, without the Moon there probably would be no life on Earth."
