Shoushi calendar (tropical year of 365.2425 days)
Calendario Shoushi y año trópico de 365,2425 días
- Date
- 1280-1281 · confidence high
- Place
- Dadu (Beijing), China
- Credited to
- Guo Shoujing, Wang Xun and Xu Heng
- People
- 👤 Guo Shoujing1231–1314👤 Wang Xun👤 Xu Heng1209–1281
- Field
- Cosmos & Earth
What was discovered
With a 40-foot gnomon at Gaocheng and a network of 27 observatories, they fixed the length of the year at 365.2425 days, the same value later adopted by the Gregorian calendar. It remained in force for 364 years.
The value matches that of the Gregorian calendar (1582), obtained independently.
What it led to
- official Chinese calendar until 1644
- third-order interpolation methods in astronomy