Source This design is based on the Suzhou star-chart rubbing (Song dynasty planisphere). Chinese astronomy differs from the ecliptic-based Chaldeo-Greek tradition by its equatorial character, due to the central role of the polar star (Biot, 1862; de Saussure, 1930). The celestial region close to the equator is divided into 28 asterisms, called xiu (宿) — “mansions” or “lunar lodges” — an equatorial Chinese zodiac. A mansion is defined by the hourly interval between the meridian passage of two successive leading stars. Beyond the equatorial region, the rest of the sky is divided into nearly three hundred small asterisms, most tied to practical objects or persons of the Chinese empire.
[ Source: Dunhuang VII, Atlas Coelestis ]