Polar Motion

Polar motion is the movement of Earth’s rotation axis relative to its crust, shifting the geographic poles by several meters over time. It results from mass redistribution within Earth’s system — including the atmosphere, oceans, and hydrosphere — and changes in angular momentum. Polar motion is continuously monitored by Earth Orientation Parameters (EOP), which link the terrestrial and celestial reference frames.

More Info: https://geodesy.science/item/earth-orientation-parameter/