Washington, D.C.: Water — the key ingredient for life — may not have only arrived on planets through comets or asteroids, as long believed. According to a new study published in Nature on October 30, scientists now suggest that planets can generate their own water internally during their formation.
In a series of cutting-edge laboratory experiments, researchers at the Carnegie Institution for Science, led by Anat Shahar, simulated the extreme heat and pressure found deep inside young planets — where molten rock interacts with hydrogen gas. Their findings reveal that liquid water can form naturally as these worlds take shape, a discovery that could redefine our understanding of how Earth and other habitable planets obtained their life-sustaining resource.
How Planets Create Water
The researchers used a diamond anvil cell — a device capable of generating immense pressure — to compress molten, iron-rich rock to nearly 600,000 times Earth’s atmospheric pressure and heat it to more than 7,200°F (about 4,000°C).
Under these intense conditions, hydrogen atoms bonded with oxygen from iron oxides present in the molten rock, producing water.
“This process shows that water doesn’t have to be delivered from elsewhere in space,” the researchers noted. “It can form naturally as part of a planet’s own evolution.”
Implications for Habitable Worlds
This finding supports a growing theory that water formation is a natural byproduct of planetary development, meaning that planets rich in hydrogen and iron — like early Earth — could produce water internally.
The team focused on sub-Neptune analogues — planets between Earth and Neptune in size — since they are the most common type found in our galaxy. These rocky, hydrogen-rich planets are now thought to have a greater chance of containing oceans or atmospheres capable of supporting life.
Lead researcher Anat Shahar said the discovery could greatly expand the number of potentially habitable exoplanets. “Planetary formation itself can create water,” she explained, “which means worlds like ours may be far more common than we ever imagined.”
What’s Next
Future research will explore how water interacts with other planetary materials and how these processes influence atmospheric composition, surface chemistry, and the potential for life. Scientists hope such insights will guide future space telescopes and missions in identifying ocean-bearing exoplanets orbiting distant stars.
If confirmed across other planetary systems, this could be one of the most profound shifts in understanding how life-supporting environments emerge throughout the universe.