Built in 1422, when Yong Le moved the Chinese capital to Beijing, the Imperial Observatory had a major part to play in the decision-making processes of Chinese emperors.
As suggested by Confucius, an ethical ruler should perform certain rituals at precisely the right time of year, or he would subject himself and his people to natural and man-made disasters.
Because of this, an emperor would base even minor decisions on the advice of his astronomers: when is a good time to go hunting? Try Tuesday or Thursday, but definitely not Friday.
Originally, measurements were based on a combination of Mongol and Islamic techniques, but in 1603 Matteo Ricci arrived in Beijing and brought with him European timekeeping innovations, which began a period of over a hundred years of Jesuit influence on Beijing’s timekeeping.
When you enter the two-storey compound today, you’ll see various nautical instruments along with sundials and other astrological devices.
On the roof are a number of bronze tools for measuring the position of the stars (these are perhaps replicas cast by Jesuits who were enlisted as astronomers during the Qing dynasty), which the ancient astronomers would have used.
The instruments have beguiling names such as celestial globe, dragon quadrant, ecliptical armilla and azimuth theodolite.