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鈥檚 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 鈥渋nner inner core鈥� 600 kilometres across. It鈥檚 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).