When you buy through links on our articles, Future and its syndication partners may earn a commission.Credit: NASALife 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.AdvertisementAdvertisement”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.Artist’s illustration of a planet-forming disk around a newborn star. | Credit: NASA/JPL-CaltechEarth 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.The study suggests that oxygen levels must fall within a surprisingly narrow range for both phosphorus and nitrogen to stay in a planet’s mantle and crust. Too little oxygen, and phosphorus bonds with iron and is dragged into the core, depriving the surface of a key ingredient for DNA, cell membranes and energy transfer. Too much oxygen, and nitrogen is more easily lost to space. Either way, the chemistry needed for life never fully comes together.AdvertisementAdvertisementUsing models of planetary formation and geochemical behavior, the researchers found that Earth sits squarely inside this narrow range of medium-level oxygen, which they called the chemical Goldilocks zone. Ultimately, our planet retained enough phosphorus and nitrogen to later fuel biology — a result that may be far from common among rocky worlds.”Our models clearly show that the Earth is precisely within this range,” Walton said in the statement. “If we had had just a little more or a little less oxygen during core formation, there would not have been enough phosphorus or nitrogen for the development of life.”Conversely, the researchers also modeled the formation of other planets such as Mars, where oxygen levels were outside this chemical Goldilocks zone. On Ma …
