THE solid metallic inner core of the Earth may hide yet another, even deeper core.
More than 60 years ago, geologists discovered that the Earth’s core is divided into a liquid outer core and a solid inner one. Now Miaki Ishii and Adam Dziewonski of Harvard University have spotted what appears to be a distinct “inner inner core” 600 kilometres across. It’s also solid, but has crystallised differently, possibly reflecting two episodes of inner core development, the researchers write in Proceedings of the National Academy of Sciences (DOI: 10.1073/pnas. 172508499).
