Guo Shoujing

Directed the compilation of the Shoushi Calendar, among the most accurate in the world at the time, and built many hydraulic works.

Life

Youth of Xingzhou

Guo Shoujing came from a scholarly family in Xingzhou. As a child he studied arithmetic and hydraulics with his grandfather, an expert mathematician, and as a young man he helped repair local canals and weirs and survey water sources. His outstanding ability got him recommended to the court, where he was highly valued by Kublai Khan, and thereafter he long took part in the Yuan dynasty's calendar reform and in planning hydraulic works in Dadu and along the canals.

Shoushi Calendar

He improved astronomical observation instruments such as the armillary sphere and the simplified armillary sphere, and directed large-scale astronomical surveys at 27 observation sites across the country. On this basis he completed the Shoushi Calendar in 1281, which measured the length of the year as 365.2425 days, almost exactly the same as the current Gregorian calendar, making it one of the most accurate calendars in the world at the time. He also directed the digging of the Tonghui River, linking Dadu with the Beijing–Hangzhou Grand Canal and easing grain transport.

Reappraised

The Shoushi Calendar remained in use for more than 360 years and was one of the longest-used and most accurate calendars in the history of ancient Chinese calendrics. Guo Shoujing's achievements were long credited more to an abstract "flourishing of Yuan science and technology," and his own specific innovations in instrument design and observation methods were fully revealed and recognized only after modern research in the history of science deepened.

Legacy

Guo Shoujing was one of the most outstanding scientists of ancient China. The Shoushi Calendar, based on large-scale observations, was among the most accurate in the world at the time and remained in use in China for more than 300 years; the instruments he designed, such as the simplified armillary sphere, were structurally quite advanced. The Tonghui River, whose excavation he directed, solved Dadu's grain transport problem. His achievements represent the peak of Yuan science and technology and have won broad international recognition in modern times.

Major works & achievements

• Oversaw compiling the Shoushi Calendar
• Created the simplified armillary sphere, tall gnomon and other instruments
• Led the "Survey of the Four Seas" astronomical observation
• Dug the Tonghui River

Did you know? The international astronomical community has named an asteroid and a lunar crater after him.

Key dates

• 1231Born in Xingzhou
• 1262Recommended to the court and appointed superintendent of rivers and canals
• 1276Commissioned to help reform the calendar
• 1279Directed nationwide astronomical surveys
• 1281Shoushi Calendar promulgated
• 1293Tonghui Canal completed and opened to shipping
• 1316Died in Dadu