January 24, 2023
Far below our feet, a giant may have started moving against us.
Earth's inner core, a hot iron ball the size of Pluto, has stopped spinning in the same direction as the rest of the planet and might even be rotating the other way, research suggested on Monday.
Roughly 5,000 kilometers (3,100 miles) below the surface we live on, this "planet within the planet" can spin independently because it floats in the liquid metal outer core.
Exactly how the inner core rotates has been a matter of debate between scientists—and the latest research is expected to prove controversial.
What little is known about the inner core comes from measuring the tiny differences in seismic waves—created by earthquakes or sometimes nuclear explosions—as they pass through the middle of the Earth.