Earth wobble measured with unmatched precision by ring laser
by Robert Schreiber
Berlin, Germany (SPX) Sep 07, 2025

The Technical University of Munich has achieved a breakthrough in monitoring the Earth's axis, recording its subtle wobbles with a precision unmatched by previous instruments. Results of a 250-day experiment, published in Science Advances, demonstrate that the TUM ring laser provides accuracy 100 times greater than earlier gyroscopes or ring lasers.

Lead author Prof. K. Ulrich Schreiber of TUM's Institute of Engineering for Astronomical and Physical Geodesy explained that these measurements provide critical data for high-accuracy Earth system modeling. The wobble of Earth's axis, long known but difficult to track in detail, arises from multiple influences. The planet's equatorial bulge drives precession, tracing a 26,000-year circle in the sky, while gravitational pulls from the Sun and Moon add shorter-period nutations, including an 18.6-year cycle and additional weekly and daily variations.

Unlike older methods requiring multiple large radio telescopes spread across continents, the TUM ring laser captures these effects directly from a single underground site in Wettzell. The instrument achieved continuous monitoring with temporal resolution below one hour, and results available immediately, compared to delays of days or weeks with very long baseline interferometry (VLBI).

Researchers see further potential in the technology. If its sensitivity improves by another factor of 10, it could measure spacetime distortions from Earth's rotation, providing a direct surface-based test of Einstein's relativity through the Lense-Thirring effect.

Research Report:Gyroscope Measurements of the Precession and Nutation of the Earth Axis

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