GoKawiilStudy 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.
GoKawiil's interpretation of the reporting above, not reported fact.
Pinpointing which forces govern these subtle rotational shifts could help scientists better model Earth's deep interior, a region that remains largely inaccessible to direct observation. The findings may also inform ongoing debates about the behavior of the inner core, including questions about its rotation relative to the rest of the planet.
- New Nature study models three possible torque mechanisms—mechanical, electromagnetic and gravitational—linking core dynamics to day-length variation.
- Day-length changes are extremely small, measured in milliseconds over decades, but reveal deep-Earth processes.
- Findings could improve understanding of core-mantle coupling and debates over the inner core's rotation behavior.
Source: nature.com — Dinneen, 2026-09-23
Published there as: “Gravitational tug-of-war inside Earth is changing the length of our days”
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