Earth's Water Is Officially Older Than the Sun. That's Incredible.

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  • Astronomers connected water from the interstellar medium to our water, showing distinct similarities.

  • The research team believes the finding shows water in our solar system is older than the sun.

  • Water observations in a protostar unlock clues about the formation of comets.


Water holds a fundamental place in star and planet formation. By looking at the water on protostar V883 Orion, a mere 1,305 light-years from Earth, scientists found a "probable link" between the water in the interstellar medium and the water in our solar system. That likely means our water is billions of years older than the sun.

"We can think of the path of water through the universe as a trail," John Tobin, an astronomer at the National Science Foundation's National Radio Astronomy Observatory and lead author on a new paper published in Nature, says in a news release. "We know what the endpoints look like, which are water on planets and in comets, but we wanted to trace that trail back to the origins of water."

We've got a better understanding of that now. Before the work by the astronomers, scientists could link Earth to comets, and protostars to the interstellar medium—that space residing between stars—but they couldn't link protostars to comets. Finding the water on V883 Orion changes all that and proves the "water molecules in that system and our solar system have a similar ratio of deuterium and hydrogen."

That means this path of water through the universe, as Tobin calls it, is much longer—and older—than previously believed.

Margot Leemker, an astronomer at Leiden University and a coauthor of the paper, explains in the news release:

“It is known that the bulk of the water in the interstellar medium forms as ice on the surfaces of tiny dust grains in the clouds. When these clouds collapse under their own gravity and form young stars, the water ends up in the disks around them. Eventually, the disks evolve, and the icy dust grains coagulate to form a new solar system with planets and comets. We have shown that water that is produced in the clouds follows this trail virtually unchanged. So, by looking at the water in the V883 Ori disk, we essentially look back in time and see how our own solar system looked when it was much younger.”

Using the Atacama Large Millimeter/submillimeter Array (ALMA), astronomers found that V883 Ori was just hot enough to turn from ice to gas, allowing the study.

To make the connection between V883 Ori and our own solar system, the team measured its composition and found that it remains relatively unchanged between each stage of formation, protostar, protoplanetary disk, and comets.

"This means that water in our solar system was formed long before the sun, planets, and comets formed," Merel van 't 'Hoff, a University of Michigan astronomer and co-author of the paper, says in the news release. "We already knew that there is plenty of water ice in the interstellar medium. Our results show that this water got directly incorporated into the solar system during its formation. This is exciting as it suggests that that our planetary systems should have received large amounts of water, too."

This is a big deal in understanding the formation of Earth. “Until now, the chain of water in the development of our solar system was broken," Tobin says. "V883 Ori is the missing link in this case, and we now have an unbroken chain in the lineage of water from comets and protostars to the interstellar medium.”

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