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Gravitational torque between Earth's inner core and mantle drives multidecadal day-length changes

As of September 2026: Published in Nature, September 2026

Earth's day is not a fixed 24 hours; it stretches and shrinks by fractions of a millisecond over cycles of roughly 60 to 70 years. A Nature paper published September 23 identifies the engine behind those changes: gravitational pull between the solid inner core and the rocky mantle above it.

Updated Sep 25