Precession is the slow wobble of Earth’s axis over a period of 26,000 years caused by the combined gravitational tugs of the sun and moon. As a spinning top slows down, you’ve probably noticed that the axis of the top describes a little circle (wobble) in the air before eventually tipping over. The Earth’s axis traces out a similar circle in the sky. Since the pole star is determined by where our axis points, it follows that the pole star will shift position and change in sync with that wobble. Right now, Polaris in the Little Dipper occupies the hallowed spot at which our axis points, but in 14,000 A.D., brilliant Vega will displace Polaris as the pole star. Due to the cyclic nature of precession, Polaris will return as the North Star again in 28,000 A.D.