Earth's Water May Have Formed Internally, New Study Suggests

Scientists have put forward a new theory suggesting that Earth's water may not have come from external sources like comets or meteorites, but instead formed internally from the planet's own rocky materials during its early development. This groundbreaking idea challenges previous assumptions about the origin of the vast oceans that cover our planet.

The research, conducted by scientists from the University of New Mexico and published in Nature Geoscience, posits that as Earth formed approximately 4.5 billion years ago, rocky pebbles rained down from the surrounding protoplanetary disc. These pebbles, rich in iron oxide, are believed to have reacted with a hydrogen-rich atmosphere under extreme heat. This chemical reaction, according to the theory, produced water and pure iron, the latter of which would have contributed to the formation of Earth's metallic core.

Previous scientific consensus often relied on the idea that water arrived on Earth via impacts from icy comets or water-rich meteorites originating from the colder, outer regions of the solar system. However, this new hypothesis suggests that such external delivery might not have been necessary to account for the sheer volume of water on Earth.

To test their theory, researchers conducted laboratory experiments. They heated rock samples to temperatures between 1,200°C and 1,400°C (2,190–2,550°F) while exposing them to streams of hydrogen and, for comparison, helium. The results showed that approximately 80% of the iron oxide in the samples reacted with hydrogen to form metallic iron and water within minutes. No such reaction occurred when the samples were exposed to helium, indicating that the presence of hot hydrogen was crucial.

Professor Zachary Sharp, a co-author of the study and a planetary scientist at the University of New Mexico, stated that extrapolations from their experiments suggest that hundreds of oceans' worth of water could have been produced through this internal process. "Looking out over a large body of water, it is hard to imagine that that water may have been produced 4.5 billion years ago in a hell-like atmosphere, but it very well may have," Sharp remarked.

This theory has significant implications not only for understanding Earth's history but also for the search for extraterrestrial life. Scientists believe that many rocky planets form through a similar process called pebble accretion. If this water-forming mechanism is common, it suggests that numerous Earth-sized planets orbiting other stars could also possess abundant liquid water, increasing the potential for life beyond our solar system. "By extension, it is reasonable to expect that other Earth-sized bodies circling other stars would also have water and possibly life," Professor Sharp added.