Water surprise in planet formation: Could be much more common

NEWS CENTER

Created: November 11, 2025 12:59

Using a special device ( a diamond anvil cell ) operating between the tips of two diamonds, the scientists compressed molten rock samples to approximately 600,000 atmospheres of pressure and heated them to over 4,000°C (10,000°F). This simulates the interior of young planets with "magma oceans" surrounded by a thick, hydrogen-rich atmosphere. Under these conditions, hydrogen mixes with the molten rock and reacts with iron oxides, creating liquid water. This means water can form internally as a natural consequence of planet formation.

The team used pulsed laser heating in their experimental setup to reduce the risk of hydrogen damaging the diamonds. This safely tested both silicate and metal melts, and showed that hydrogen not only converted to water but could also be stored within magma. This points to the possibility of an "internal reservoir" that could fuel water production later in the planet's history. In short, Earth's water didn't have to come entirely from outside; the chemistry between the planet's building blocks and its early atmosphere could have produced significant amounts of water internally.

THE NEW ADDRESS OF WATER

The notion that "water accumulates in cold regions far from the Sun and is subsequently transported," a common scientific notion, is tempered by these findings. The research suggests that rock-gas interactions could support water production on "sub-Neptunian" planets—planets larger than Earth but smaller than Neptune, with thick hydrogen atmospheres. Thus, deep oceans could chemically emerge beneath the thick atmospheres of even warmer worlds relatively close to their stars. This scenario requires rethinking numerous models, from early climate and volcanism to core formation and atmospheric evolution.

WHY IS IT IMPORTANT?

Water is a fundamental requirement for life. The demonstration that water can be produced internally suggests that "habitable" worlds may be more common in the universe than previously thought. The likelihood of water being found on planets that don't rely on external ice delivery increases, particularly in different star types and orbits. In the future, this experimental framework will help us more accurately calculate the "internal resource" share of Earth's water budget and more accurately interpret water signatures seen in the atmospheres of distant exoplanets.