Guo Shoujing

From Wiki China org cn

In 1279, the astronomer Guo Shoujing (1231-1316) devised a number of astronomical instruments, including the armillary sphere and celestial body, and used them to conduct a series of large-scale geodetic surveys and celestial observations in 27 places in China. According to the results of his observations, Guo formulated the Shoushi Calendar, which became the most advanced calendar of that time, and used for the longest time. He calculated a solar year to be 365.2425 days, the same as the Gregorian calendar.

Model of Guo Shoujing's abridged armillary sphere