NASA researchers track Earth’s shifting center of mass

Scientists led by NASA’s Jet Propulsion Laboratory have developed a new method to precisely calculate the seasonal oscillations of Earth’s center of mass. Published in the Geophysical Journal International, the study details how the redistribution of mass across the planet causes the center of mass to shift slightly relative to its geometric center.

These shifts, which occur in fractions of an inch, are driven by the global water cycle. Seasonal changes such as spring snowmelt, ocean currents, and atmospheric density variations move massive amounts of matter. For instance, snow accumulation in North America and Eurasia can shift the center of mass approximately 3 millimeters toward the North Pole in March. Conversely, heavy rainfall in the Amazon basin can cause a shift of about 2.2 millimeters toward South America in April.

While these movements do not alter Earth’s orbit around the Sun, accurately tracking the geocenter is vital for satellite navigation and altitude measurements. The new methodology combines GPS observations, laser ranging, and low-Earth orbit satellite data to improve the precision of these measurements.