North star closer to Earth than previously thought

[Judi Lynn]

November 30, 2012, 3:45 PM
North star closer to Earth than previously thought

The famed North Star has been a beacon in the night sky throughout human history, but a new study reveals the star is actually closer to our solar system than previously thought.

Scientists studying the North Star Polaris found that it is about 323 light-years from the sun and Earth, substantially closer than a previous estimate of 434 light-years by a European satellite in the late 1990s. The new distance measurement may help astronomers in the pursuit of several cosmic mysteries, such as the hunt for elusive dark energy, researchers said.

Polaris is what astronomers call a Cepheid variable star, a pulsating star used by scientists to measure distances in space. Astronomers can measure the distance to a Cepheid variable by studying how it changes in brightness over time.

Since Polaris is the nearest Cepheid variable star to our solar system, an accurate distance to the star could serve as a benchmark for measurements of other Cepheids used to determine the scale of the universe.

More:
http://www.cbsnews.com/8301-205_162-57556534/north-star-closer-to-earth-than-previously-thought/

[longship]

1. Polaris is also a double star.

My copy of Burnham's Celestial Handbook (1978) states that it's over 300 LY away, without stating specifics.

It is good that astronomers have resolved this. Measuring distances is difficult. Fortunately, Alpha Ursa Minoris is a Cepheid variable. Not a very bright star, about 49th brightest in our northern skies (according to Burnham).