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Future North Poles

July 18, 2020

Perhaps the most famous star in the night sky is Polaris. It’s not especially bright or close by. Instead, it’s famous for its location. It marks the north celestial pole, so it’s also known as the North Star or Pole Star. Today, it’s about two-thirds of a degree from the true celestial pole. But over the next century, it’ll snuggle even closer.

The change is caused by a slow “wobble” in Earth’s rotation. Over a period of 26,000 years, that causes our planet’s axis to draw a big circle on the northern sky. So while Polaris itself will still be around, it won’t keep its position as the North Star.

The axis is moving counterclockwise. So the next moderately bright star it’ll point to is Gamma Cephei. It’s to the right or lower right of Polaris as darkness falls this month. It’ll take over as the North Star in about a thousand years.

After moving past another star of Cepheus, the pole will take aim at Deneb, the “tail” of Cygnus, the swan, around the year 10,000. And 3500 years after that we’ll have the brightest pole star of all, Vega. Neither Deneb nor Vega will be all that close to the true celestial pole, but their brilliance will make up for the gap.

And in about 20,000 years, the pole will come around to Thuban. It marked the pole about 4500 years ago, when it helped architects align the pyramids of Giza. Finally, around the year 28,000, the pole will return to Polaris — closing its great circle on the sky.


Script by Damond Benningfield

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