Earth's inner core may be changing shape, with its surface possibly swelling and contracting. Recent analyses suggest the inner core's rotation may have slowed down and even reversed direction relative to the surface around 15 years ago. A new study found that the inner core's surface is likely morphing, with possible deformation or changes in its shape.

The researchers used seismic waves from earthquakes to study the inner core, as no instrument can physically probe it. They analyzed about 200 pairs of earthquakes that occurred from 1991 to 2024 and found that 10 doublets showed subtle differences in waveforms that could indicate changes in the inner core's shape.

The changes could be driven by the gravitational pull of the mantle or material flowing in the outer core. While the findings may not affect life on Earth, more research is needed to understand the implications of the inner core's changes.