Does the North Star ever change? In other words, will Polaris always be the North Star?
Yes, the North Star does change, and Polaris will not always be it. Like a top, Earth’s axis precesses; that is, it slides along the surface of an imaginary cone. The precessional motion is very slow; one complete cycle of the axis about the cone requires about 26,000 years. In the course of 26,000 years, the north celestial pole will move on the celestial sphere along a circle of approximately a 23-1/2 degree radius, centered on the pole of the ecliptic (where the perpendicular to Earth’s orbit intersects the celestial sphere). In the 20th century, the north celestial pole is very near Polaris, but in about 12,000 years, the celestial pole will be fairly close to the bright star Vega.
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