Polaris the North Star

Polaris was so named because it was judged to sit just above the North Pole. It has guided mariners for centuries from this position. Interestingly enough, it has not always held this prominent position. Before 2300 BC the star closest to maintaining a polar position was in the constellation Draco. Nevertheless, the reader should not worry about the North Star moving again anytime soon. Polaris will remain the "North Star" until about 12000 AD when it will be supplanted by Vega. Such celestial changes occur because of the wobble of the Earth's axis.

The North Star in Autumn

The North Star is fairly easy to find, even when the evening sky is somewhat obscured by city lights. Besides residing generally in the north, the most prominent constellation in the sky points directly at it. The two stars at the end of the ladle form a line, as can be seen in our diagram.

As the seasons change, if the Big Dipper is viewed at the same time every night it will seem to circle around Polaris. In the spring, for example, just after sunset the ladle of the Big Dipper will appear above the North Star and will point down at it, instead of up.

Polaris is the last star on the handle of a minor constellation generally known as the Little Dipper, but more classically known as Ursa Minor. This constellation is difficult to see in the city because of the surrounding "light pollution". Even so, Polaris, on a clear night should easily be seen. It is the 40th brightest star in the night sky. Even so, it is a huge star, 2200 times brighter than our own sun. It only appears dimmer to us because of its distance, which is in the range of 430 light years from Earth. (A light year is the distance you could travel in a year moving at the speed of light.)

A common simile in literature is "True (or steady) as the North Star." This is because the star does not seem to move as the Earth spins. It hangs above the horizon at an angle approximately equal to the degree of latitude of the observer. From the North Pole it looks to be directly overhead. (Actually, it is about 1.5 degrees off.) At 45 degrees North Latitude it would appear 45 degrees off the horizon at due north. As the night progresses the entire night sky appears from Earth to revolve around Polaris in a counter-clock-wise progression.

Many people have been inspired by this star. Corporations, institutes, snowmobiles, ad infinitum, all bear the name, hoping to benefit from the reputation of the "Navistar". Yet it is interesting to note that the star derives its fame only relative to we tiny beings inhabiting a tiny planet circling a relatively small star. From most other positions of the galaxy the constellations and more particularly our North Star would appear completely different. Indeed, from the Southern Hemisphere of our own planet, the North Star cannot be seen at all, the mass of our own planet obliterates the view.

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Interesting Fact:

Polaris, or the North Star, is almost directly above the North Pole. It is about two-thirds of a degree off. An observer standing on the North Pole would see Polaris if he or she looked straight up.


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