The Chandler Wobble Theory
Earth spins on its axis of rotation. But it doesn’t spin perfectly. Like a toy top, it wobbles when it spins.
This displacement is known as Chandler wobbles. The Chandler wobble occurs because the Earth is not a perfect sphere.
It flattens out at the poles. The wobble is minuscule. It’s just 20 feet in deviation at the North Pole.
No longer a mystery, the key driver of wobbling is temperature and salinity changes at the bottom of the ocean.