Earth wobbles just slightly as it spins on its axis, similarly to when a spinning top begins to slow down. This wobble, known as precession, is primarily caused by the gravity of the sun and moon pulling on Earth's equatorial bulges.

What is precession wobble?

Precession – As Earth rotates, it wobbles slightly upon its axis, like a slightly off-center spinning toy top. This wobble is due to tidal forces caused by the gravitational influences of the Sun and Moon that cause Earth to bulge at the equator, affecting its rotation.

What is the wobble of Earth called?

The Wobble of Earth's Axis

The third orbital change that Milankovich studied is called precession, the cyclical wobble of Earth's axis in a circle. The motion is like a spinning top when it is about to fall over. One complete cycle for Earth takes about 26,000 years.