Earth’s center is moving

Earth’s center of mass is constantly on the move, shifting by a few millimeters as enormous amounts of water, ice, and even air migrate around the planet with the seasons. NASA scientists have developed a more precise way to track these tiny swings using laser-ranging satellites, GPS data, and measurements of how water and ice deform Earth’s crust. Earth’s center is moving, and NASA just measured it.

NASA scientists have developed a new technique using ultraprecise satellite tracking to estimate the displacement to within fractions of inches. As water, ice, and air move around the planet with the seasons, they redistribute enough weight to push the center of mass back and forth by fractions of an inch relative to Earth’s geometric center. NASA scientists carefully track this subtle motion because Earth’s center of mass serves as an essential reference point for satellite navigation and measurements of surface elevation.

Researchers led by NASA’s Jet Propulsion Laboratory in Southern California have now developed a method designed to measure these seasonal shifts with exceptional precision. Their technique and results are described in a new study published in Geophysical Journal International. The research shows how major seasonal changes, including melting snow, moving ocean water, and dense winter air, redistribute enormous amounts of mass across Earth’s surface.