Deep within Earth lies a solid metal core that rotates independently of the planet’s outer layers, akin to a spinning top within a larger one, enveloped in mystery.

Discovered in 1936 by Danish seismologist Inge Lehmann, this inner core’s movement—specifically its speed and direction—has intrigued scientists for decades.

Studying seismic waves from large earthquakes has provided insights into its dynamics, revealing fluctuations in its rotation speed over time.

Initially proposed in the 1970s and ’80s, the idea of differential rotation gained support in the ’90s with seismological evidence, though interpretations have varied due to the core’s inaccessibility, CNN has reported.

Recent studies, including a 2023 model, suggest the inner core once spun faster than Earth before slowing down and even briefly reversing its rotation relative to the mantle.

New research, published in June 2023, reinforces these findings, indicating a long-term pattern of fluctuations in the inner core’s rotation speed.

Written by B.C. Begley