North Star is also called Beichen, Zi Gong and Zi Wei Yuan. Polaris is an important indicator for sky navigation (that is, identifying directions by observing celestial bodies) and can be used in field activities and navigation activities. Before there was a compass, seafaring peoples, especially those near the Mediterranean, often navigated by observing the North Star.
Polar Star refers to the star closest to the North Celestial Pole and is the polar star visible in the northern hemisphere. The current North Star is Alpha Ursa Minor (Gouchen 1).
Due to the precession of the equinox, the North Star is different in different periods. About 4,800 years ago, the North Star at that time was Alpha Draconis. In ancient Greek times, the North Star was Beta Ursa Minor. By around 2100, the angle between the current Alpha Ursae Minoris and the North Pole will become the smallest (only 27'38"). After the 31st century, Gamma Ursae Minoris (γ Cephei) will become the North Star. Around 14,000 years , Alpha Lyra (Vega) will become the North Star
Extended information
Unlike the Western astronomical system centered on ecliptic coordinates, ancient China developed an astronomical system centered on equatorial coordinates. In this system, Polaris is located in the true north of the celestial sphere, and it undoubtedly has a unique status. It was often used as a symbol of the emperor in ancient China. However, Alpha Ursa Minor has not been the Polaris since ancient times due to the periodic slow swing of the earth's rotation axis. Therefore, the position in the sky where the North Pole of the Earth's rotation axis points is also changing, and the "throne" of Polaris may also take turns.
The sky where the Earth's rotation axis points to the North Pole moves at a speed of 15 arc seconds per year. 3000 years ago, Polaris was not Alpha Ursae Minoris, but Alpha Draconis, a dark star of magnitude 3.7. In ancient China, it was called Youshu. By 1000 BC, Beta Ursae Minoris (Chinese name Polaris II) ) is relatively close to the North Celestial Pole. Since all the stars in the sky revolve around it, the ancients thought it was the Son of Heaven in the sky, so it was also named Emperor Star. Because it is in the center of Ziwei Yuan, it was also called Ziwei Star.
During the Sui and Tang Dynasties, Polaris (32H in Camelopardalis) became the North Star. This star was extremely dim and was the dimmest North Star in the history of human civilization until the 21st century. In the early years of the Northern Song Dynasty in China, The sky where the Earth's North Pole points is still 6 degrees away from the North Star Alpha Ursa Minor (i.e. Gouchenyi). It can be seen that it was far from being the North Star at that time, but by the Ming and Qing Dynasties, Gouchenyi had become the polar star. A veritable North Star
Baidu Encyclopedia - North Star