One of the other things that's intriguing about Polaris is that it's what astronomers refer to as a Cepheid Variable star. "This star pulsates because it is in a state that is unstable," says Palma. "It will swell up, and when it does, an outer layer of the star becomes transparent, which then makes the star cool off. As a result of it cooling off, it will shrink until it becomes opaque again, which causes it to heat up and swell again. It will do this over and over again, pulsating in and out, which causes its brightness to fluctuate."
And although you can't tell when you gaze at Polaris in the night sky, it's actually part of a triple star system. "The two fainter stars (Polaris Ab and B) do not vary in brightness because they are on the 'main sequence,' or are generating energy by fusing hydrogen nuclei into helium nuclei only in the core of the star," Schuler explains.
Polaris won't be the North Star forever. "If you look at the 14,000 C.E. point, you'll see a star that's much, much brighter than Polaris but farther from the circle," Fienberg says. "That's Vega, which our descendants some 12,000 years from now (if humans are still around) will consider their North Star."
Originally Published: Nov 20, 2019