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Earth’s inner core may be changing shape

The entire surface of the inner core, or small patches of it, may be swelling and contracting

The primary layers of the Earth, including its solid inner core, are shown.

The surface of Earth’s solid inner core, which rotates within the liquid outer core, may be changing.

vchal/iStock/Getty Images Plus

By Nikk Ogasa

WASHINGTON, D.C. — Earth’s inner core, a solid metal ball gyrating within the molten outer core, may be both slowing down and changing shape.

Recent analyses of earthquake waves have suggested that around 15 years ago, the inner core’s rotation may have slowed so much that it appeared to pause or reverse direction relative to the surface.