Space.com by Samantha Mathewson 2/10/26
Without the right oxygen balance, phosphorus and nitrogen vanish — and life can't take hold.Life on Earth may exist thanks to an incredible stroke of luck — a chemical sweet spot that most planets miss during their formation but ours managed to hit.
A new study shows that Earth formed under an unusually precise set of chemical conditions that allowed it to retain two elements essential for life as we know it: phosphorus and nitrogen. Without a perfect balance of these elements, a rocky planet could appear habitable on the surface yet be fundamentally incapable of supporting biology, according to the study.
"During the formation of a planet's core, there needs to be exactly the right amount of oxygen present so that phosphorus and nitrogen can remain on the surface of the planet," study lead author Craig Walton, of ETH Zurich in Switzerland, said in a statement.
Earth seems to have hit this delicate chemical sweet spot during its formation nearly 4.6 billion years ago, and the new findings could change how scientists search for alien life, the researchers said.
When young planets form, they are often partially or fully molten. As heavy metals sink inward to form a core, lighter materials remain closer to the surface. During this chaotic stage, known as core formation, the amount of oxygen present plays a decisive role in determining where other elements end up — and whether they remain accessible for future life.
More:
https://www.space.com/space-exploration/search-for-life/life-on-earth-is-lucky-a-rare-chemical-fluke-may-have-made-our-planet-habitable
