Why is the polar star (Pole star) important?

Answer: (b) It indicates the direction of the north pole

Polaris sits almost above the North Pole, showing true north.

The idea

A star near the extension of Earth’s rotation axis appears to stay almost fixed while other stars circle around it. This makes it a useful direction marker. In the northern hemisphere, the angle of Polaris above a level horizon is approximately the observer’s latitude.

Why the others are wrong

(a) Sirius is brighter.

(c) There is no bright south pole star.

The trap

“Brightest” is a myth — Polaris is only ~48th brightest.

Also know

The two outer stars of the Big Dipper’s bowl help locate Polaris. Near the equator Polaris is close to the horizon; near the North Pole it is nearly overhead. Earth’s axis slowly changes direction through precession, so the same star does not remain the pole marker for all of history.