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Liu Chao
Sui classicist and calendar maker whose Huangji calendar first used second-order interpolation for solar and lunar motion but was never adopted
On an observatory terrace at night, a large bronze armillary sphere stands on a stone base while two people stand with their backs turned facing the view; stars are joined into constellation lines overhead, and a sundial and tiered dripping water vessels stand at the right.
Also known as Zi Shiyuan
- Roles
- Scientist
Liu Zhuo, courtesy name Shiyuan, came from Changting in Xindu. As a youth he and Liu Xuan studied the classics together and then read behind closed doors for ten years; the pair were known as the Two Lius. In the Kaihuang era he passed the examination with top marks, worked on the dynastic history and calendar reform, but quarrels with other scholars led to his dismissal, and he went home to teach and write. In the Renshou years he completed the Huangji calendar, which used equal-interval second-order interpolation to model the uneven motion of sun and moon and set precession at one degree in seventy-five years, but the court astronomer Zhang Zhouxuan kept it from being adopted. He also proposed measuring noon shadows at points a thousand li apart to test the old claim that the shadow changed by one inch per thousand li. He died in 610, and Li Chunfeng drew on his methods for the Tang Linde calendar.
Life and times
Dates 544 CE–610 CE