What astronomical phenomenon causes the identity of the North Star to change over thousands of years?

Answer

The precession of the equinoxes

Due to the slow wobble of the Earth’s axis over extremely long periods, known as the precession of the equinoxes, the North Celestial Pole slowly wanders, causing the closest star to change over millennia.

What astronomical phenomenon causes the identity of the North Star to change over thousands of years?
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