Water is one of the major building blocks of life and Earth has an abundance of it, as 71 percent of its surface is covered by water, largely due to its expansive oceans. Now a new study theorizes that Earth’s water may have been carried to our planet from ancient comets, millions of years ago.
The study, published in Astronomy and Astrophysics Letters, looked at data from NASA’s Stratospheric Observatory for Infrared Astronomy (SOFIA) and found that there were similarities to the water contained on the comet Wirtanen and the water on Earth.
“We have identified a vast reservoir of Earth-like water in the outer reaches of the solar system,” said the study’s lead author, Darek Lis, a scientist at NASA’s Jet Propulsion Laboratory, in a statement. “Water was crucial for the development of life as we know it. We not only want to understand how Earth’s water was delivered, but also if this process could work in other planetary systems.”
The study’s co-author, Dominique Bockelée-Morvan, a scientist at the Paris Observatory and the French National Center for Scientific Research, said that it’s the first time researchers are able to “relate the heavy-to-regular water ratio of all comets to a single factor.”
Also known as 46P, the Wirtanen comet was discovered by the American astronomer Carl Wirtanen in January 1948.
Illustration of a comet, ice grains and Earth’s oceans. SOFIA found clues in Comet Wirtanen’s ice grains that suggest water in comets and Earth’s oceans may share a common origin. (Credit: NASA/SOFIA/L. Cook/L. Proudfit)
The researchers found that the water contained an extra neutron inside one of the hydrogen atoms, chemically known as HDO; regular water is chemically known as H2O. The authors concluded that if comets contain the same ratio of water types as Earth’s oceans, they may share a common origin.
“We may need to rethink how we study comets because water released from the ice grains appears to be a better indicator of the overall water ratio than the water released from surface ice,” Bockelée-Morvan added.
SOFIA is a NASA lab aboard a modified Boeing 747SP jetliner that is able to carry a 106-inch diameter telescope. It is managed by NASA’s Ames Research Center and is a joint project between NASA and the German Aerospace Center, DLR.