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Gravitational forces inside Earth drag some decades out — and make others fly by

Nature作者：Dominique Jault2026年9月23日正文已收录本站
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Variations in day length that occur on multidecadal timescales are caused by gravitational coupling between Earth’s inner core and its solid mantle.

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  1. Dominique Jault

    1. Dominique Jault is at the Institute of Earth Sciences (ISTerre), University of Grenoble Alpes, CNRS, Grenoble 38058, France.

  2. Paolo Personnettaz

    1. Paolo Personnettaz is at the Institute of Earth Sciences (ISTerre), University of Grenoble Alpes, CNRS, Grenoble 38058, France.

The rate at which Earth spins, and therefore the length of the day, fluctuates on scales ranging from hours to millennia. Decadal variations that alter day length by a few milliseconds are caused by the transfer of angular momentum between the planet’s core and the solid mantle that surrounds it. Several mechanisms for this transfer have been proposed but now, writing in Nature, Zhang and Dumberry1 report that these multidecadal variations can be traced to gravitational coupling between the inner core — a solid ball of iron that floats in the liquid outer core — and the mantle. This result was obtained by linking seismological measurements that reveal how the inner core rotates with a model of the core’s flow derived from measurements of Earth’s magnetic field.

doi: https://doi.org/10.1038/d41586-026-02773-1

References

  1. Zhang, H. & Dumberry, M. Nature https://doi.org/10.1038/s41586-026-10999-2 (2026).

    Article  Google Scholar 

  2. Istas, M., Gillet, N., Finlay, C. C., Hammer, M. D. & Huder, L. Geophys. J. Int. 233, 1890–1915 (2023).

    Article  Google Scholar 

  3. Buffett, B. A. Geophys. Res. Lett. 23, 2279–2282 (1996).

    Article  Google Scholar 

  4. Yang, Y. & Song, X. Nature Geosci. 16, 182–187 (2023).

    Article  Google Scholar 

  5. Wang, W., Vidale, J. E., Pang, G., Koper, K. D. & Wang, R. Nature 631, 340–343 (2024).

    Article  PubMed  Google Scholar 

  6. Aubert, J. J. Stud. Earth Deep Inter. 2, 3 (2026).

    Article  Google Scholar 

  7. Gillet, N., Jault, D., Canet, E. & Fournier, A. Nature 465, 74–77 (2010).

    Article  PubMed  Google Scholar 

  8. Finlay, C. C., Gillet, N., Aubert, J., Livermore, P. W. & Jault, D. Nature Rev. Earth Environ. 4, 377–392 (2023).

    Article  Google Scholar 

  9. Oliver, T. G., Blackman, E. G., Tarduno, J. A. & Calkins, M. A. Commun. Earth Environ. 6, 484 (2025).

    Article  Google Scholar 

  10. Wu, K., Song, X. & Yang, Y. Geophys. Res. Lett. 53, e2025GL119295 (2026).

    Article  Google Scholar 

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Competing Interests

The authors declare no competing interests.

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