Scientists have long debated the origin of Earth's water. One theory is that it came from comets and asteroids that impacted the Earth early in its history. Another theory is that it was present on Earth from the time it formed.
The Carnegie Institution study looked at the composition of water in Earth's mantle and compared it to the composition of water in comets and asteroids. The researchers found that the composition of the water in Earth's mantle is very different from the composition of the water in comets and asteroids.
The researchers also looked at the amount of water on Earth and compared it to the amount of water that would have been delivered by comets and asteroids. They found that there is much more water on Earth than comets and asteroids could have delivered.
The researchers concluded that Earth's water did not come from comets and asteroids. They suggest that it came from chemical reactions that occurred inside the Earth shortly after it formed.
