Scientists May Have Finally Figured Out Where Earth's Water Came From

The discovery could lead to a "foolproof method for detecting signs of life on other worlds."

Primordial Accretion

Scientists say they may have finally cracked the case on where the water on Earth — and other planets like it — came from billions of years ago.

As detailed in a new paper published in the journal Nature, primordial water may have formed as a result of hydrogen-rich atmospheres colliding with magma oceans roiling on the surface of planetary embryos, small celestial objects that clump together to form into planets like the Earth.

"Exoplanet discoveries have given us a much greater appreciation of how common it is for just-formed planets to be surrounded by atmospheres that are rich in molecular hydrogen, H2, during their first several million years of growth," said co-author Anat Shahar, a researcher at the Carnegie Institution for Science, in a statement. "Eventually these hydrogen envelopes dissipate, but they leave their fingerprints on the young planet's composition."

Water Signs

We've long suspected that rocky planets like the Earth formed as dust and gas surrounding the Sun accreted over time. These planetesimals became incredibly hot as they grew, forming vast magma oceans.

The primordial ball that eventually became Earth had its densest material sink towards its core as it cooled down, resulting in our planet's distinct layers.

Now, researchers have found some enticing clues about how water, by far the most abundant resource on Earth, may have formed during this process after studying the makeup of planets orbiting other stars.

The researchers' new models suggest that interactions between planetesimal magma oceans and molecular hydrogen could have led to our planet's abundance of water and oxygen gas.

These interactions would be enough, even if all the material clumping together to form the Earth was completely dry, to account for all of the water on Earth, according to the researchers' models.

Signs of Life

But plenty of questions remain, and the researchers were quick to point out this may be just one way for water to form.

"This is just one possible explanation for our planet's evolution, but one that would establish an important link between Earth's formation history and the most common exoplanets that have been discovered orbiting distant stars, which are called Super-Earths and sub-Neptunes," Shahar said in the statement.

The researcher is hoping that with the advent of "increasingly powerful telescopes," we could have an even closer look at the atmospheres of exoplanets, which could eventually allow us to establish a "foolproof method for detecting signs of life on other worlds."

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