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
Researchers Hao Zhang and Mathieu Dumberry report in Nature that gravitational coupling between Earth's solid inner core and its mantle explains multidecadal changes in day length of a few milliseconds. They combined seismological data on inner-core rotation with a model of outer-core flow derived from magnetic field measurements to reach this conclusion.
nature.com
· 2026-09-23
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
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