For an agricultural economy like China, it was of vital importance that the people to be told of the beginning and end of the rainy seasons, or the rise and the fall of the rivers. At some time unbeknownst to us, the ancient Chinese came to discover that there were mysterious yet subtle links between the seasons and the movement of celestial bodies across the sky. From then on, the Chinese became the most persistent and assiduous sky watchers, and devised one of the most accurate calendars in the world.

Compared with its western counterparts, ancient Chinese astronomy constitutes a vastly different system of its own. Seeing the sky as a miniature of the earthly world, the Chinese divided the heavens into the Three Enclosures and Twenty-eight Mansions. Kings, nobles, aristocrats, important government officials and comers all had their special places in the sky. Unlike the West, astronomy and astrology in traditional China never parted from each other. The Chinese emperors hoped, through the study of astronomy, to be forewarned of their dynastic destinies or any looming calamities that would befall the nation. The Imperial Astronomical Bureau was set up to observe, record and interpret astronomical phenomena in detail. Against this backdrop, the ancient Chinese not only invented a multitude of astronomical instruments which boasted remarkable accuracy, they also kept the most comprehensive astronomical records.