Earth's Inner Core Is As Hot As The Surface Of The Sun

Deep beneath your feet, 3,200 miles down, sits a solid ball of iron and nickel the size of Pluto. Earth's inner core simmers at 5,200 degrees Celsius — the same temperature as the surface of the Sun. It remains solid not because it is cool, but because the pressure is crushing: 3.6 million atmospheres. Floating inside a churning ocean of molten outer core, its slow, slightly faster-than-Earth rotation helps generate our magnetosphere, the invisible shield that deflects deadly solar wind. First proposed by seismologist Inge Lehmann in 1936, the inner core grows by about one millimeter per year as liquid iron freezes. Without it, compasses would wander and life would be exposed to radiation.