The unique chemical composition of Earth, particularly the precise amount of oxygen present during its formation, may be the key reason why our planet is capable of supporting life, according to new research. Understanding these conditions is crucial as scientists continue the search for habitable planets beyond our solar system.
A study led by Craig Walton, a postdoctoral researcher at the Centre for Origin and Prevalence of Life at ETH Zurich, along with Professor Maria Schönbächler, reveals that the balance of oxygen during the formation of Earth’s core allowed essential elements like phosphorus and nitrogen to remain accessible for life to develop. The research, published February 9, 2026, in the journal Nature Astronomy, suggests this is a rare “chemical luck” in the universe.
During the Earth’s formation approximately 4.6 billion years ago, the amount of oxygen present dictated where these vital elements would end up. “During the formation of the planet’s core, there had to be just the right amount of oxygen for phosphorus and nitrogen to remain on the planet’s surface,” Walton explained.
Too much oxygen, and nitrogen would have been lost to the atmosphere. Too little, and phosphorus would have sunk into the core. The study highlights that Earth landed in a very specific “chemical Goldilocks zone” – not too reductive and not too oxidative – allowing these elements to remain readily available.
Researchers used modeling to demonstrate that only within a narrow range of moderate oxygen levels could both phosphorus and nitrogen survive in sufficient quantities in the mantle. “Our models clearly show that Earth is right within this range. If we had a little more or a little less oxygen during core formation, there wouldn’t be enough phosphorus or nitrogen for life to develop,” Walton stated.
This imbalance, as seen on planets like Mars, creates a chemical environment unsuitable for life as we know it. The availability of oxygen during planet formation is heavily influenced by the chemical makeup of the host star. Since planets form from the same material as their stars, the star essentially determines the chemical characteristics of the entire planetary system.
“This makes the search for life on other planets much more specific. We need to look for solar systems with stars that resemble our Sun,” Walton added. The findings suggest that Earth’s habitability isn’t solely due to being in the “habitable zone” with liquid water, but also to its unique chemical origins.
The Institute of Geochemistry and Petrology at ETH Zurich continues to investigate the complex factors that contribute to planetary habitability, examining samples from both our planet and beyond. This research provides a new lens through which to evaluate the potential for life elsewhere in the universe, emphasizing the importance of specific chemical conditions.
As detik.com reports, the study underscores that water alone is not enough to support life; a very specific chemical combination is required.
