Earth's center of mass, also called the geocentric barycenter, is not a fixed point inside the planet. It moves as mass is redistributed among the oceans, ice sheets, atmosphere and solid Earth, causing seasonal and interannual shifts. Although these motions are subtle, they affect high‑precision geodesy and satellite orbit determination.
To quantify this motion researchers combined data from the GRACE‑FO satellite twin mission, which measures variations in Earth's gravity field, with ground‑based satellite laser ranging that provides millimeter‑accurate distance measurements. The combined approach enables detection of center‑of‑mass shifts at the scale of a few millimeters.
The analysis revealed that the seasonal component of the drift is considerably smaller than previously thought. Earlier estimates had suggested shifts on the order of several centimeters per year, whereas the new results indicate only a few millimeters, prompting a reassessment of the magnitude of mass exchange within the Earth system.
These refined numbers improve the accuracy of global reference frames, enhance sea‑level change estimates and refine predictions of satellite trajectories. Better knowledge of the barycenter’s motion helps reduce error sources in climate studies and navigation applications.