Question

What is the Pole Star? How can the Saptarishi be used to locate it?

Answer 1

HintIt is also named the North Star, it is the brightest star that appears closest to either celestial pole at any particular time. Owing to the precession of the equinoxes, the position of each pole defines a small circle in the sky over a period of more than 25000 years.

Step by step solutionThe Pole Star is the only star that is recognized for retaining its position in the sky always. We can locate the position of the Pole Star referring to the constellation Saptarishi. If an imaginary line is drawn joining the “pointer stars” of the Saptarishi and extended further, it will point to the Pole Star automatically. A pole star or polar star, both are the same. Shining bright, nearly aligned with the axis of a rotating astronomical body. In order to navigate Polaris, all you have to do is, search for the Big Dipper pointer stars that are called Dubhe and Merak. These two stars are the only stars that outline the outer part of the Big Dipper's bowl. Simply draw an illusionary line from Merak through Dubhe, and go about five times the Merak/Dubhe distance to Polaris. If you can locate the Big Dipper, you can find Polaris automatically.

Note As of now, Earth's pole stars are Polaris (Alpha Ursae Minoris), which is a magnitude-2 star aligned approximately with its northern axis, and a pre-eminent star in celestial navigation, and Polaris Australis (Sigma Octantis), a much dimmer star. From around 1700 BC until just after 300 AD, Kochab and Pherkad were twin northern pole stars, though neither was as close to the pole as Polaris is now.