生平

元太宗三年（1231年），郭守敬生于邢州境內的邢台。

王恂、郭守敬等同一位尼泊爾建築師阿尼哥合作，在元大都興建了一座新天文台，台上就安置著郭守敬所創製的天文望遠鏡。它是當時世界上設備最完善的天文台之一。

元至元元年（1264年），科學家郭守敬與唆脫顏前在寧夏視察河渠水道，負責修複寧夏平原附近因長期戰亂而破壞淤塞的渠道。郭守敬提出建滾水壩以減弱水勢，在渠道引水處築堰以提高水位，建渠首進水閘以保証渠道有充足水量，建退水閘以調節流量等技術方案，為水利工程之創新，共修複疏浚興州、靈州、應理州、鳴沙州等四州主乾渠12條、支渠68條，使寧夏平原9萬餘頃土地恢復了灌溉。這次修複的沿河渠道壩閘，設計精細，質量堅固，直到明代中期還在繼續使用。

郭守敬曾擔任都水監，負責修治元大都至通州的運河通惠河。1276年修訂新曆法，經4年時間制訂出《授時曆》，通行360多年，是當時世界上最先進的一種曆法。

他採用了類似現在球面三角算法的「弧矢割圓術」來處理黃道和赤道的坐標換算，在計算太陽、月亮和行星原形位置時創造運用了「招差法」，也就是三次差內插法。並設計製作了多種天象觀測儀器，包括簡儀和高表。組織了大量的天象觀測工作，包括測定恆星位置，測定冬至點、近地點以及黃道和白道交點位置，編制月亮運動表，測定全國27個觀測點的緯度。確定了一個月為29.530593日，一年為365.2425日。正式廢除以前曆法積累的時差，以實際觀測為准。確定以一年的1/24作為一個節氣，以沒有中氣的月份為閏月，此原則一直採用至今。

1279年郭守敬提案「四海測驗」，奉旨後進行，聽從郭守敬的建議元世祖派了14位天文家，除大都外到當時國內另外26個地點，進行幾項重要天文觀測。這一天文觀測的規模之大，在世界天文史上也是少見的。在其中的6地點特別測定了夏至日的表影長度和晝、夜的時間長度。這些觀測的結果，都為編制全國適用曆法提供了科學的數據。

今日為了紀念他，邢台市將一條主要的街道命名為「守敬路」（即現在橋西區的守敬北路和守敬南路），還設立郭守敬紀念館（在達活泉公園內）。

現存于河南嵩山的郭守敬觀星台是研究天文的儀器，系郭守敬所建。觀星台曾于1944年遭侵華日軍炮擊，沒有被完全破壞，後被中國文物部門修複。

紀念

小行星2012以郭守敬的名字命名。1981年，為紀念郭守敬誕辰750周年，國際天文學會以他的名字為月球上的一座環形山命名。

2010年4月17日上午，LAMOST望遠鏡冠名儀式正式舉行。LAMOST望遠鏡被正式冠名 為「郭守敬望遠鏡」。

注釋

Early life

In 1231, in Xingtai, Hebei province, China, Guo Shoujing was born into a poor family. He was raised primarily by his paternal grandfather, Guo Yong, who was famous throughout China for his expertise in a wide variety of topics, ranging from the study of the Five Classics to astronomy, mathematics, and hydraulics. Guo Shoujing was a child prodigy, showing exceptional intellectual promise. By his teens, he obtained a blueprint for a water clock which his grandfather was working on, and realized its principles of operation. He improved the design of a type of water clock called a lotus clepsydra, a water clock with a bowl shaped like a lotus flower on the top into which the water dripped. After he had mastered the construction of such water clocks, he began to study mathematics at the age of 16. From mathematics, he began to understand hydraulics, as well as astronomy.

Career

At 20, Guo became a hydraulic engineer. In 1251, as a government official, he helped repair a bridge over the Dahuoquan River. In the late 1250s, Kublai Khan became the Khan and ruler of most of China, which was under Mongol rule. Kublai Khan realized the importance of hydraulic engineering, irrigation, and water transport, which he believed could help alleviate uprisings within the empire, and sent Liu Bingzhong and his student Guo to look at these aspects in the area between Dadu (now Beijing or Peking) and the Yellow River. To provide Dadu with a new supply of water, Guo had a 30 km channel built to bring water from the Baifu spring in the Shenshan Mountain to Dadu, which required connecting the water supply across different river basins, canals with sluices to control the water level. The Grand Canal, which linked the river systems of the Yangtze, the Huai, and the Huang since the early 7th century, was repaired and extended to Dadu in 1292–93 with the use of corvée (unpaid labor). After the success of this project, Kublai Khan sent Guo off to manage similar projects in other parts of the empire. He became the chief advisor of hydraulics, mathematics, and astronomy for Kublai Khan.

Guo began to construct astronomical observation devices. He has been credited with inventing the gnomon, the square table, the abridged or simplified armilla, and a water powered armillary sphere called the Ling Long Yi. The gnomon is used to measure the angle of the sun, determine the seasons, and is the basis of the sundial, but Guo Shoujing revised this device to become much more accurate and improved the ability to tell time more precisely. The square table was used to measure the azimuth of celestial bodies by the equal altitude method and could also be used as protractor. The abridged or simplified armilla was used to measure the angle of the sun, as well as the position of any celestial body. The Ling Long Yi is similar to an abridged armilla except larger, more complex, and more accurate. Kublai Khan, after observing Guo's mastery of astronomy, ordered that he, Zhang, and Wang Xun make a more accurate calendar. They built 27 observatories throughout China in order to gain thorough observations for their calculations. In 1280, Guo completed the calendar, calculating a year to be 365.2425 days, just 26 seconds off the year's current measurement. In 1283, Guo was promoted to director of the Observatory in Beijing and, in 1292, he became the head of the Water Works Bureau. Throughout his life he also did extensive work with spherical trigonometry. After Kublai Khan's death, Guo continued to be an advisor to Kublai's successors, working on hydraulics and astronomy.

Personal life

Death

His year of death is variously reported as 1314 or 1316.

Analysis of his contributions

Guo Shoujing was a major influence in the development of science in China. The tools he invented for astronomy allowed him to calculate an accurate length for the year, which allowed Chinese culture to set up a whole new system of exact dates and times, allowing for increasingly accurate recording of history and a sense of continuity throughout the country. The calendar stabilized the Chinese culture allowing subsequent dynasties to rule more effectively. Through his work in astronomy, he was also able to more accurately establish the location of celestial bodies and the angles of the Sun relative to Earth. He invented a tool which could be used as an astrological compass, helping people find north using the stars instead of magnets.

Within the field of hydraulics, even at a young age, Guo was revolutionizing old inventions. His work on clocks, irrigation, reservoirs, and equilibrium stations within other machines allowed for a more effective or accurate result. The watches he perfected through his work in hydraulics allowed for an extremely accurate reading of the time. For irrigation, he provided hydraulics systems which distributed water equally and swiftly, which allowed communities to trade more effectively, and therefore prosper. His most memorable engineering feat is the man-made Kunming Lake in Beijing, which provided water for all of the surrounding area of Beijing and allowed for the best grain transport system in the country. His work with other such reservoirs allowed people in inner China access to water for planting, drinking, and trading. Guo's work in mathematics was regarded as the most highly knowledgeable in China for 400 years. Guo worked on spherical trigonometry, using a system of approximation to find arc lengths and angles. He stated that pi was equal to 3, leading to a complex sequence of equations which came up with an answer more accurate than the answer that would have resulted if he did the same sequence of equations, but instead having pi equal to 3.1415.

As people began to add onto his work, the authenticity of his work was questioned. Some believe that he took Middle Eastern mathematical and theoretical ideas and used them as his own, taking all the credit. However, he never left China which would have made it more difficult for him to access others' ideas. Otherwise, Guo was highly regarded throughout history, by many cultures, as a precursor of the Gregorian calendar as well as the man who perfected irrigation techniques in the new millennium. Many historians regard him as the most prominent Chinese astronomer, engineer, and mathematician of all time.

His calendar would be used for the next 363 years, the longest period during which a calendar would be used in Chinese history. He also used mathematical functions in his work relating to spherical trigonometry, building upon the knowledge of Shen Kuo's (1031–1095) earlier work in trigonometry. It is debated amongst scholars whether or not his work in trigonometry was based entirely on the work of Shen, or whether it was partially influenced by Islamic mathematics which was largely accepted at Kublai's court. Sal Restivo asserts that Guo Shoujing's work in trigonometry was directly influenced by Shen's work. An important work in trigonometry in China would not be printed again until the collaborative efforts of Xu Guangqi and his Italian Jesuit associate Matteo Ricci in 1607, during the late Ming Dynasty.

Influence

Guo Shoujing was cited by Tang Shunzhi 唐順之 (1507–1560) as an example of solid practical scholarship, anticipating the rise of the Changzhou School of Thought and spread of the "evidential learning".

Asteroid 2012 Guo Shou-Jing is named after him, as is the Large Sky Area Multi-Object Fibre Spectroscopic Telescope near Beijing.