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Earth inner core deformation and rotation speed

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2026-09-30 18:03 UTC → 2026-10-03 03:15 UTC · added ~~removed~~

Physicists from the University of Alberta, including Huifeng Zhang and Mathieu Dumberry, have published research in the journal Nature regarding how the Earth’s inner core influences the planet’s rotation speed. The study indicates that the solid inner core is slightly elliptical and undergoes a deformation process approximately every 70 years. As the core oscillates, it shifts mass relative to irregularities in the Earth’s mantle, triggering an exchange of angular momentum. This process, which functions similarly to a figure skater changing rotation speed by moving their arms, causes the length of a day to fluctuate by several milliseconds. While short-term variations in rotation are attributed to atmospheric changes, ocean currents, and melting glaciers, these findings suggest that long-term changes are driven by deep-seated gravitational and electromagnetic forces acting between the Earth’s layers. Further research into these fluctuations highlights the role of the liquid outer core, which is composed primarily of iron and nickel. This layer rotates at a different rate than the layers above it, creating a differential rotation between the outer core and the mantle. This interaction involves the exchange of angular momentum and energy driven by gravitational torque and electromagnetic forces. Observations suggest that the lowermost mantle may conduct electricity, allowing the flow of the molten outer core to exert electromagnetic stress on it, effectively coupling the two layers and influencing the planet's overall spin.

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