Scientists have long puzzled over just how the core of our planet was formed, and new research out of Stanford University suggests that it could have been a long and complicated process. The research shows that the core could have been formed through a process called percolation, which involves molten iron trickling through the solid silicate layer of the Earth to reach the center. It's a theory that has existed for some time, but the new research provides further evidence that it could have actually happened.

"Scientists had said this theory wasn't possible."

To recreate the conditions of the core's formation, researchers used tiny amounts of iron and silicate rock, which were squeezed inbetween the tips of diamonds and shot with laser beams in order to simulate the intense pressure and extreme heat found at the center of the planet. Once everything had cooled down, X-ray imaging was used to determine that percolation was indeed a possibility, though it's a process that would have taken place over millions of years, as the temperature and pressure shifted to varying degrees. "Scientists had said this theory wasn't possible, but now we're saying, under certain conditions that we know exist in the planet, it could happen," explains study lead Wendy Mao.

"This new data suggests that we cannot assume that core formation is a simple, single-stage event," the University of Edinburgh's Geoffrey Bromiley, who wasn't part of the research, told the BBC. "Core formation was a complex, multi-stage process that must have had an equally complex influence on the subsequent chemistry of the Earth."