The pole star is a star of medium brightness, it is by no means the brightest in the sky. In terms of overall range, there are quite a few stars brighter than this one. In fact, Polaris isn’t even in the top 40 (it ranks 48th).
Why is it so well known then?
The reason that Polaris or Pole Star is so important is because the Earth’s axis is pointing almost directly at it . During the course of the night, the pole star does not rise or set, it remains almost at the same point on the northern horizon throughout the year, not like the other surrounding stars.
Hence, at any time of the night, at any time of the year in the northern hemisphere, we can easily find the pole star ; it is always in a northerly direction. If you were at the North Pole, Polaris would be directly overhead.
However .. Polaris will not always be the North Star.
Polaris is a Cepheid variable, which means that it has a regular cycle of brightness and dimming, similar to other stars of its kind. However, it has gotten brighter over the past two decades, for reasons that are not yet fully understood. While the star is still relatively faint, as of 2014, a group of scientists estimated that Polaris could be around 4.6 times brighter today than it was in ancient times.
How to find the pole star
Polaris is in the constellation Ursa Minor. The seven stars with which we draw the little bear make up Ursa Minor. Among all of them, Polaris, the North Star, is in the tail. Also, it is the brightest of the seven – the others are quite faint. With very little moonlight or city lighting, most of the stars in Ursa Minor are invisible to our eyes.
The best way to find Polaris is to use a pair of stars within the constellation Ursa Major (also known as The Chariot): first locate its “Big Dipper” asterism, which is visible throughout the year in the Northern Hemisphere; then the stars Dubhe and Merak, which form the back of the drawing of El Carro. We have to draw a line between these two stars and draw it about five times, and we will unequivocally run into Polaris.
Interestingly, Ursa Major and Ursa Minor are arranged so that when one constellation is upright, the other is upside down. Also, its ends appear to extend in opposite directions. Of course, the Big Dipper is the brighter of the two.
Interesting Facts About the Pole Star
Polari s is located at a distance of 434 light years from Earth and has a luminosity almost 4,000 times that of our sun. Polaris shines in 2nd magnitude. On this astronomical scale, the smaller numbers represent brighter objects, with the brightest stars and planets in the night sky having a magnitude of around zero or even negative magnitude.
The North Star is a “pulsating” star that appears to vary slightly in brightness (only one-tenth of a magnitude) over a period of just four days.
Seeing Polaris in the northern sky depends on our latitude. From New York, for example, it is 41 degrees above the northern horizon, which also corresponds to the latitude of New York. At the North Pole, you would find it right above your head. At the equator, Polaris appears to sit right on the horizon. As we travel north, the star progressively rises as we move in this direction. When you head south, the star descends further and finally disappears once you cross the equator and head towards the southern hemisphere.
And always keep this fact in mind: Polaris is more accurate than any compass . A compass is subject to periodic variations and can only show you the direction of the strongest magnetic force lines for a particular point and for a particular time. But even Polaris is not positioned exactly north. Only about 0.7 degrees separate Polaris from the point known as the Celestial North Pole, the imaginary point where the stars move.
