Astronomical Observation
Astronomical observation, built during the period from the 13th and 16th year of Yuan Dynasty and having a history of more than 730 years, is the most intact existing astronomical observation instrument of Yuan Dynasty. According to its design, it could measure the length of the shadow of the sun so that seasons could be determined. In addition, it could help to observe the movement rules of the sun, the moon, and stars so that calendar could be made. Astronomical observation is the only existing observation among the 27 observations built by eminent astronomist Guo Shoujing of Yuan Dynasty during his measurement (1276 – 1279) of geological latitudes of different places of China, the first ever national wide measurement of its kind in Yuan Dynasty. With data collected by Guo Shoujing, Wang Xun and other people, the most advanced calendar of that period in the whole world, Shoushili had been published in 1281. Shoushili has calculated the length of a year as 365.2425 days, whose accuracy is as precise as today’s Gregorian calendar. The solid observation station, built from bricks and having accurate construction dimensions, is true representation of scientific architectural development of China in the 13th century. The observation is important pioneering work in world’s architecture and science. Zhougong observation on the south of astronomical observation is the instrument used by people in ancient China to measure the length of the shade of the sun and to confirm the division of seasons. It is comprised of two parts, pedestal and stand which are named as Gui and Biao respectively. At noon of summer solstice, there is no shade of Biao on the observation, where the observation is called shadeless observation. Hence, noon of summer solstice was regarded as earth centre in ancient China. Astronomical observation, Zhougong observation and Zhougongmiao temple comprise of a complete temple. And on the central axis stand buildings of Ming and Qing Dynasties including Zhaobi, Damen, Jinmen, Zhougongci temple and Diraodian temple. In addition, there are 12 tablet inscriptions and duplicates of astronomical instruments inside astronomical observation, all being important astronomical relics. Astronomical observation has been included in the first group of key national protection relics by the state council on March 4 of 1961.