Polaris III

StarDate: February 21, 2013

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If paparazzi chased the real stars, the one with the biggest following would be the most famous star of all: the North Star, Polaris. It’s the hub of the northern sky — all the other stars appear to rotate around it.

Yet despite its fame — and centuries of study — Polaris retains some mystery. In fact, one mystery is its distance.

An orbiting spacecraft measured the distance at about 435 light-years. It plotted Polaris’s position compared to more distant stars when Earth was on opposite sides of the Sun. The shift in Polaris’s apparent position revealed its distance.

But a study released last year came up with a distance that’s a hundred light-years closer. The study was led by David Turner of Saint Mary’s University in Nova Scotia. The team broke Polaris’s light into its individual wavelengths, and compared the results to models of how stars like Polaris behave. That technique showed that Polaris must be closer than revealed by the space mission.

The difference is important because Polaris is a type of star that astronomers use to measure distances to other galaxies. Those measurements, in turn, help reveal the distances to much farther galaxies. And those measurements help probe the rate at which the universe is expanding, and the effect of mysterious dark energy.

So learning the intimate details of the night sky’s most famous star is more than just nosiness — it’s a critical clue in understanding the fate of the entire universe.

 

Script by Damond Benningfield, Copyright 2012

For more skywatching tips, astronomy news, and much more, read StarDate magazine.

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