What is the star that can only be due north in the clear night sky in the northern hemisphere?

Polaris is located at the northern end of the earth's axis, which is five times as long as the extension line connecting Tian Xuan and Shu Tian in the Big Dipper. Because the earth rotates, and Polaris happens to be on the axis of celestial rotation, it is still relative to other stars. Polaris is about 434 light years away from the earth and has a diameter of about 52 million kilometers.

"Gouchenyi" is actually composed of three celestial bodies: Polaris Aa, Polaris B and Polaris Ab. It was once named Vega, and its name comes from the story of Yan Zi Shi (matriarchal tribal leader) weaving linen clothes in the late Paleolithic period, but now it is called the North Star because it is closest to the north celestial pole.

Extended data:

Polaris is a very important directional indicator in ancient navigation and outdoor activities, ranging from stargazing to astrophotography, and it is also a directional constellation, so the precise positioning of the Equatorial Observatory in the observation room is very important. Because Polaris is closest to true north, people on earth have been navigating by its starlight for thousands of years.

In the night sky in the northern hemisphere, the Big Dipper stands out in the northern sky. These seven stars are Shu Tian (Hungry Wolf), Tian Xuan (Giant Gate), Tianji (Lucun), Tian Quan (Wen Qu), Yuheng (Lian Zhen), Kaiyang (Wu Qu) and Etta Ursa (Pojun) in Ursa major.

They look brighter than other stars and are arranged in a spoon shape. If you extend about five times in the direction of Tian Xuan and Shu Tian, you will find another bright star, the Polaris.

Baidu encyclopedia-Polaris