Where Did Earth's Water Come From? Study Suggests It Was Already Here

Where did the water on Earth come from? The findings of a new study suggest the planet was already wet.

Where the water on Earth came from seems like a simple question but it is actually one that remains a mystery. Some models of solar system formation propose that the early Earth had very little water, suggesting that the planet's water may have come from extraterrestrial objects such as asteroids or comets later on.

In a new study, a team of researchers analyzing a rare type of meteorite called enstatite chondrites found that the Earth may have been wet from the beginning.

Enstatite chondrites are a class of meteorites that are composed of the same inner solar system materials that originally created the Earth. They are said to have similar oxygen, calcium and titanium isotopes as the Earth and because of this, even if they only comprise 2% of the meteorites, they represent the building blocks of the Earth.

For a long time, enstatite chondrites were believed to be dry, particularly because they came from the inner zones of the solar system where it would be too hot for water to condense during planet formation. But after analyzing them, the researchers found that enstatite chondrites actually have enough hydrogen to explain the water on Earth.

"We show that EC meteorites contain sufficient hydrogen to have delivered to Earth at least three times the mass of water in its oceans," the researchers wrote.

This means the building blocks of Earth already had more than what it needed to fill the world's oceans even though the temperatures were too high and even without the additions from later asteroids.

"If enstatite chondrites were effectively the building blocks of our planet — as strongly suggested by their similar isotopic compositions — this result implies that these types of chondrites supplied enough water to Earth to explain the origin of Earth's water, which is amazing!" study co-author Lionel Vacher of Washington University in St. Louis said in a news release.

Study lead author Laurette Piani said the assumption that enstatite chondrites are dry could have prevented the analysis for hydrogen. Thanks to the new study, we now know that may not even be the case at all.

The study was published in the journal Science.