The pole star, known as Polaris, is famous for being nearly still in our sky while the entire northern sky moves around it. People in ancient times determined directions during the night with the help of stars.
Being the most useful in determining the directions, Polaris is not easy to locate as there are about 50 more objects in the night sky brighter than Polaris. (Refer the picture below to get an idea how confusing this would be)
How to locate the Polaris?
Polaris is easy to locate by using the prominent group of stars known as the Big Dipper.
Big Dipper known as ‘The Saptarishi’ who are identified with the seven rishis of ancient India, Agastya, Atri, Bharadwaj, Gautam, Jamdagni, Vashistha and Vishwamitra. The corresponding western names of these stars are: Dubhe, Merak, Phad, Megrez, Alioth, Mizar and Alkaid.
To locate the Polaris, all you have to find is the Big Dipper pointer stars ‘Dubhe’ and ‘Merak’ and simply draw a line from Merak through Dubhe, and go about five times the Merak/Dubhe distance to Polaris.
The Big Dipper, like a great big hour hand, goes full circle around Polaris in one day. More specifically, in a counter-clockwise direction in 23 hours and 56 minutes. Although the Big Dipper travels around Polaris all night long, the Big Dipper pointer stars always point to Polaris on any day of the year, and at any time of the night. Polaris marks the centre of Nature’s grandest celestial clock!
You can observe the entire sky rotating around the Polaris in above Timelapse.
History of Polaris.
Polaris hasn’t always been the North Star and won’t remain the North Star forever. For example, a famous star called Thuban, in the constellation Draco the Dragon, was the North Star when the Egyptians built the pyramids.
Our present Polaris, being sky’s 50th brightest star, it’s still noticeable. Polaris will continue its reign as the North Star for many centuries to come. It will align most closely with the north celestial pole – the point in the sky directly above Earth’s north rotational axis – on March 24, 2100.
Meanwhile, there is no visible star marking the celestial pole in the Southern Hemisphere. Southern Hemisphere won’t see a pole star appreciably close to the south celestial pole for another 2,000 years. In a way, we are quite lucky :P
Information courtesy : earthsky.org