All Those Nuclear Tests Decades Ago Have Revealed Something New About Our Planet's Core

(Rob Atkins/Getty Images) You probably remember learning about Earth's internal layers when you were a kid in Earth Sciences class: a superhot, solid inner core, surrounded by a molten metal outer core (how metal!), and a solid-but-viscous mantle made of melted rocks. On top of all this stuff sliding around is the thin, solid crust that makes up humanity's entire world. That understanding of…