Researchers studying decades of earthquake data say they have found the first evidence that, in addition to spinning backward, Earth’s inner core in changing shape.

Scientists of course cannot cut into Earth and directly observe its insides. Instead, their knowledge is inferred from the vibrations generated by earthquakes that pass through the planet. The speed and the direction of the seismic vibrations change depending on the density and the elasticity of the rocks.

A new study shows that the inner core changed shape in just a few decades, challenging previous assumptions and revealing hidden dynamics deep within Earth.

Scientists found that the inner core’s structure changes as it rotates. It deforms at its border, potentially accumulating more material in some areas and less in others — almost like creating hills and valleys.

A new study reveals that the Earth's inner core is undergoing a structural transformation. A new study by USC scientists, published in Nature Geoscience, reveals structural changes near the Earth's inner core,

The planet’s inner core was previously thought of as a hard, solid sphere. But a new study has found that its edges are softer than realized and actually changing shape.