Earth’s solid inner core is ‘surprisingly soft’ thanks to hyperactive atoms jostling around

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An artist’s interpretation of what the Earth’s crust, mantle, outer core and inner core might look like when separated. (Image credit: Shutterstock)

Scientists recently discovered that Earth‘s inner core, which was long thought to be an unmoving ball of solid metal, might be a lot less rigid than we expected. Now, a new study suggests this surprising softness may be caused by hyperactive atoms that move around within their molecular structure much more than we realized. 

The inner core is a massive spherical lump of metal, predominantly iron, that spans roughly 760 miles (1,220 kilometers) and dates back to at least 1 billion years ago. The inner core is enveloped by the outer core — a sea of swirling liquid metals — that is in turn surrounded by a massive layer of molten rock, known as the mantle, which sits just below the solid crust we live on.