Earth's Inner Core May Be Dominated by Superionic Hydrogen

New modeling suggests the inner core could host abundant superionic hydrogen—hydrogen that flows like a liquid and conducts electricity—with the hexagonal close-packed (HCP) phase likely more stable than body-centered cubic (BCC) under core conditions. Partitioning of hydrogen is driven mainly by temperature rather than pressure, creating a radial gradient that concentrates hydrogen toward the inner-core boundary where it re-partitions into a liquid that enriches the outer core. This ongoing exchange, plus inner-core growth, could provide chemical buoyancy to power the geodynamo, while other light elements like oxygen and carbon likely further shape the core's composition and evolution.