What is a constellation?

Constellation is an indispensable part of astrology and a group of stars in the sky. Since ancient times, human beings have associated three or five stars with their mythical figures or artifacts, which are called "constellations". Constellation is a means to determine the orientation of the sky in almost all civilizations and is widely used in the field of navigation. The division of constellations is completely artificial, and different civilizations have different divisions and names. Constellations have no uniform and precise boundaries. Until 1930, in order to unify the complicated constellation division, the International Astronomical Union divided the sky into 88 official constellations with precise boundaries, so that every star in the sky belonged to a specific constellation. Most of these official constellations are based on ancient Greek myths handed down from the Middle Ages. In contrast, some widely circulated star combinations are not recognized as official constellations, such as the Big Dipper (see star list).

In the three-dimensional universe, there is no necessary connection between these stars. Their positions on the celestial sphere are similar, but in fact they may be far apart. If we were in another solar system of the Milky Way, the starry sky we saw would be completely different. Since ancient times, people have been interested in the arrangement and shape of stars, and naturally linked some stars with similar positions to form constellations.