Constellations serve as a mnemonic to aid our memory. The organization of the stars is random to the untutored eye. By finding a relationship among groups of stars, early man made it easier to both remember them and to locate them quickly among the thousands visible in a segment of sky. Gradually, these images took on beliefs about their properties and myth was woven around the natural phenomena that were thought to control fortune. This ability to notice coincidence and attach causal properties to it underlies not only superstitious belief but also lay the foundation for predicting seasons, counting years, observing comets, and eventually reaching the moon.

In China, the stars were closely tied to the events within the dynasties. The Emperor was seen as the Son of Heaven with a mandate from the power of heaven to rule. Most constellations were related to the hierarchy on earth which was seen as a reflection of that in the heavens. By the end of the Han Dynasty court astronomers had grouped 1464 stars into 283 constellations. Detail was important for advising the Emperor and predicting events. Thus, astrology led to meticulous astronomy.

On a map, regions are marked by political or regional boundaries. Cities are indicated by name. It makes it easier to read the map and to find what you are looking for. Considering the size and complexity of the heavens, it is convenient to break the sky into sectors and to name the sectors and the stars within them. In Chinese astronomy/astrology they did just that. While there are many more named constellations than are given in the table below, these major segments serve as a reference for locating objects in smaller areas of the sky just as we specify a State or Province and then a city within that area when looking for an address rather than searching the entire country.

Because the stars revolve around the celestial Pole, it is seen as the center of heaven and belongs to all directions; it is divided into three regions of sky surrounding Polaris (北极星 Běijíxīng). The three regions are: the Purple Forbidden Enclosure (紫微垣, Zǐ Wēi Yuán), the Supreme Palace Enclosure (太微垣, Tài Wēi Yuán) and the Heavenly Market Enclosure (天市垣, Tiān Shì Yuán). These regions reflect the organization of the dynastic hierarchy on earth, with the Purple Forbidden Enclosure being the most important. The concept that earthly government is organized like that of heaven gives its structure and actions legitimacy and supports the Mandate of Heaven.

The constellations or Xiù (宿) are grouped by the four directions, East, West, South and North. The dragon occupies the East and contains the constellations:

角 (Jiăo) Horn
亢 (Kàng) Neck
氐 (Dĭ) Root
房 (Fáng) Room
心 (Xīn) Heart
尾 (Wěi) Tail
箕 (Jī ) Winnowing basket