Outer Core - GoKawiil

Study: Inner core's gravity pull tied to Earth's shifting day length

Researchers publishing in Nature propose that gravitational interactions between Earth's inner core and mantle help explain decades-long changes in the length of a day. Because the inner core rotates at a slightly different rate than the rest of the planet, it becomes misaligned with mass irregularities in the mantle, and the resulting gravitational pull works against other core-mantle interactions. Geophysicist Mathieu Dumberry and colleagues say this tug-of-war produces small accelerations and decelerations in Earth's spin over time.

wired.com · 2026-09-26

Study links Earth's day-length changes to core-mantle torque forces

A study published in Nature reports that small variations in the length of Earth's day, on the order of milliseconds over decades, can be explained by competing gravitational, mechanical and electromagnetic forces between Earth's solid inner core, molten outer core and rocky mantle. Researchers, including geophysicist Mathieu Dumberry, had long suspected core-mantle interactions caused these fluctuations but lacked clarity on which specific forces were responsible.

nature.com · 2026-09-23