A new study suggests Earth’s water may not have come from comets or asteroid impacts after all—it may have been here from the very beginning.
Researchers from the University of Oxford and the UK’s synchrotron science facility analyzed rare meteorites called enstatite chondrites (ECs), which closely resemble the materials that built Earth 4.55 billion years ago. Using a powerful X-ray technique (XANES spectroscopy), they found surprisingly high levels of hydrogen embedded deep within these ancient space rocks.
Crucially, this hydrogen was located within pristine regions of the meteorites, not in areas that could be contaminated after falling to Earth. The findings suggest that hydrogen from ECs could have naturally bonded with oxygen in early Earth’s rocks, forming water without any need for cosmic “delivery.”
This challenges the long-held theory that water arrived later through impacts by icy comets or hydrated asteroids. Instead, water may have been a built-in feature of the planet-forming process itself. By showing that Earth’s ingredients already included enough hydrogen for ocean formation, the study reframes our understanding of how life-supporting environments emerge on rocky planets.
It’s a discovery that simplifies one of science’s biggest questions: where did Earth’s water come from? Maybe... it was always here.
RESEARCH PAPER
Thomas J. Barrett et al., “The source of hydrogen in Earth’s building blocks,” Icarus (2025)
Researchers from the University of Oxford and the UK’s synchrotron science facility analyzed rare meteorites called enstatite chondrites (ECs), which closely resemble the materials that built Earth 4.55 billion years ago. Using a powerful X-ray technique (XANES spectroscopy), they found surprisingly high levels of hydrogen embedded deep within these ancient space rocks.
Crucially, this hydrogen was located within pristine regions of the meteorites, not in areas that could be contaminated after falling to Earth. The findings suggest that hydrogen from ECs could have naturally bonded with oxygen in early Earth’s rocks, forming water without any need for cosmic “delivery.”
This challenges the long-held theory that water arrived later through impacts by icy comets or hydrated asteroids. Instead, water may have been a built-in feature of the planet-forming process itself. By showing that Earth’s ingredients already included enough hydrogen for ocean formation, the study reframes our understanding of how life-supporting environments emerge on rocky planets.
It’s a discovery that simplifies one of science’s biggest questions: where did Earth’s water come from? Maybe... it was always here.
RESEARCH PAPER
Thomas J. Barrett et al., “The source of hydrogen in Earth’s building blocks,” Icarus (2025)
A new study suggests Earth’s water may not have come from comets or asteroid impacts after all—it may have been here from the very beginning.
Researchers from the University of Oxford and the UK’s synchrotron science facility analyzed rare meteorites called enstatite chondrites (ECs), which closely resemble the materials that built Earth 4.55 billion years ago. Using a powerful X-ray technique (XANES spectroscopy), they found surprisingly high levels of hydrogen embedded deep within these ancient space rocks.
Crucially, this hydrogen was located within pristine regions of the meteorites, not in areas that could be contaminated after falling to Earth. The findings suggest that hydrogen from ECs could have naturally bonded with oxygen in early Earth’s rocks, forming water without any need for cosmic “delivery.”
This challenges the long-held theory that water arrived later through impacts by icy comets or hydrated asteroids. Instead, water may have been a built-in feature of the planet-forming process itself. By showing that Earth’s ingredients already included enough hydrogen for ocean formation, the study reframes our understanding of how life-supporting environments emerge on rocky planets.
It’s a discovery that simplifies one of science’s biggest questions: where did Earth’s water come from? Maybe... it was always here.
RESEARCH PAPER
Thomas J. Barrett et al., “The source of hydrogen in Earth’s building blocks,” Icarus (2025)
