Jan. 31 (UPI) -- Researchers have narrowed down the list of light elements likely found in Earth's core.
Roughly 85 percent of Earth's core is iron. Another 10 percent is nickel. That leaves 5 percent unaccounted for.
Researchers have long hypothesized some combination of light elements comprise the missing portion. Now, lab experiments suggest the most likely light element candidates are hydrogen, silicon and sulfur.
Scientists at Tohoku University, in Japan, replicated core conditions using a variety of elements, subjecting the different chemic concoctions to pressures 3.6 million times greater than that measured at sea level and temperatures approaching 6,000 degrees Celsius.
For each core concoction, researchers measured the material's density and sound velocity under the extreme conditions. When hydrogen, silicon and sulfur were mixed with the iron alloy, the results most closely resembled the numbers returned by seismological observations of Earth's actual core.
Researchers detailed their findings in the journal Science Advances.
Discovering the exact composition of Earth's core is essential for the quest to properly model the core's formation and evolution; it's also key to understanding core-related phenomena like Earth's electromagnetic field.