What always indicates the north, so it is considered as the constellation with the least significant movement.

In the northern hemisphere, Polaris is undoubtedly the most important directional star. On the starry background, Polaris is less than 1 from the north celestial pole, so if you find Polaris at night, you will basically find the north. Polaris belongs to Ursa minor and is the brightest star (secondary star). Because all the stars in Ursa minor are dark except Polaris, we usually look for Polaris according to the Big Dipper.

The position of the earth's rotation axis in the sky is very stable, so people define the direction of the earth's rotation axis in the sky as south and north. Polaris is just in the direction of the earth's rotation axis, so in ancient times, when people sailed in the sea and trudged in deserts, forests and wilderness, they always turned to it to indicate the direction. People worship it so much that China even regarded it as a symbol of ancient emperors. It is in today's highly developed science and technology that Polaris is of great significance in astronomical observation, aerospace, navigation, geography and many other scientific and technological fields because of its special positioning function. In any place in the northern hemisphere, you can directly use Polaris to find the north direction.

You can search Ursa minor in Baidu Encyclopedia. There are specific things.