Every Boy Scout knows how to find the North Star; just follow the two stars on the end of the Big Dipper’s bowl, and voila… you’re there! The North Star might be the most famous star in the entire sky, yet also the most misunderstood.
Perhaps the most widespread myth about the North Star, or Polaris, is that it is the brightest star in the sky. In reality it ranks 48th. Not bad, considering there are roughly 7,000 stars visible to the naked eye from a dark location, but still far from being the most brilliant bulb in the bunch.
The importance of the North Star lies not in its brightness, but rather its location. Polaris lies almost directly above Earth’s north geographic pole. This means that no matter where you stand in the northern hemisphere, if you look towards Polaris, you’re looking almost due north, unlike a compass, which points you towards magnetic north.
Because Polaris is in line with Earth’s rotational axis, it appears virtually stationary over the course of the night, while all the other stars appear to rotate around it. This leads us to our second North Star myth.
You’ve probably heard, or even used, the phrase “constant as the North Star.” While Polaris stays put from night to night, over longer periods of time the only thing constant about the North Star is change! Earth’s axis wobbles like a top, tracing out a circle over a 25,772 year period. This process, known as precession, causes the North Pole to point towards different parts of the sky. Polaris is currently our North Star out of pure coincidence, and has been so for only the last few hundred years. When the pyramids were being built in Egypt, the North Pole was aimed in the direction of a star named Thuban, which doesn’t even crack the list of the top 300 brightest stars.
When we think about it this way, we are very fortunate that a star as bright as Polaris currently occupies this important position in the sky. Not for another 12,000 years will we have a North Star as bright and beautiful as Polaris.
Western Slope Skies is produced by members of the Black Canyon Astronomical Society. This segment was written by Zach Schierl and recorded by Art Trevena.