Tell me why it is twelve constellations instead of thirteen constellations.

Constellations originated in the west, and there are only twelve constellations in western astrology. Zodiac 12 is synonymous with the orientation of the universe. When a person is born, every star falls into the position of the zodiac, which shows a person's innate character and talent. Zodiac 12 symbolizes the psychological level and reflects a person's behavior. So the ecliptic is divided into 12 constellation, which is called 12 constellation.