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Public Radio's Environmental News Magazine (follow us on Google News)

Emerging Science Note/Star Times Three

Air Date: Week of

As Living on Earth’s Emily Taylor explains, the North star, Polaris, is actually three stars, not one.


TAYLOR: The three wise men might have been wise, but one thing they didn’t know was that they were navigating by not one star, but three. Astronomers say they finally have proof that the North Star is actually a system of three stars: Polaris A, Polaris B, and now, Polaris Ab.

Polaris B has been distinguishable, even with small telescopes, since its discovery in 1780 by William Herschel. And after working with NASA’s Hubble Space Telescope, astronomers are now able to distinguish and photograph Polaris Ab.

Because of a gravitational tug on Polaris A, astronomers thought there might be another star in the system, but Ab’s close proximity to the main star and its relative dimness made it until now impossible to see until now. Polaris Ab is about 2 billion miles from Polaris A orbits Polaris A and orbits it once every 30 years.

Although the triple star system is 430 light years from Earth, astronomers are watching Polaris Ab in order to determine its mass and orbit. They say these bits of information will assist in measuring the distances to other galaxies and the expansion rate of the universe. But, for right now, true north is still true. That’s this week’s Note on Emerging Science. I’m Emily Taylor.



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