Earth's Inner Core May Run on Superionic Hydrogen, Study Finds

New modeling suggests Earth's inner core contains abundant superionic hydrogen, predominantly in a stable hexagonal close-packed iron-hydrogen phase, with a less stable BCC form only under extreme conditions before melting. A radial hydrogen gradient drives ongoing exchange between the inner and outer core, contributing chemical buoyancy that powers the geodynamo, and the inner core is growing at about 1 millimeter per year; future work will consider other light elements like oxygen and carbon to refine core composition and evolution.