Liu Hong and the conquest of the moon

In this chapter, we look at the work of Liu Hong, who emerges as the principal technical consultant involved in the later phases of the debates discussed in the last chapter, although it seems that he only had an official post concerned with celestial observation or calculation at the beginning of his career. He created the last great astronomical system that we shall discuss—the Qian xiang li ‘Uranic Manifestation’ system. This was the first system to give a complete account of the main irregularities of lunar motion, based on a subtle analysis of the mass of data gathered by the routine observations of Han sky-watchers in preceding centuries, and made it possible to predict when solar eclipses might take place. The methods used by Liu Hong set the pattern for the handling of such questions in later centuries.