Precession of the Earth's Spin Axis
A spinning object will maintain both the magnitude and direction of its spin angular momentum unless some external torque acts to change that angular momentum. In the presence of external torque, the spinning object will precess . Observations indicate that the Earth's spin axis is precessing with a period of about 26,000 years. The spin axis currently points close to Polaris, but in 13,000 years it will be pointed about 47 degrees away from Polaris since the tilt of the spin axis with respect to its orbital plane is about 23.5 degrees.
Solar System Illustration
Solar System Concepts