Wei Pu
Encyclopedia
Wei Pu was an 11th century Chinese
astronomer
of the Song Dynasty
(960
-1279 AD). He was born a commoner, but eventually rose to prominence as an astronomer working for the imperial court at the capital of Kaifeng
. Wei became a trusted colleague of the famous statesman and scientist Shen Kuo
(1031-1095 AD), who served as the head official for the Bureau of Astronomy, and worked on various projects with Wei Pu.
system. With the aid of many different scholars and a large assortment of gathered books written on astronomy, Shen and Wei embarked on this enormous project. With the aid of Wei Pu, Shen planned to make a series of nightly astronomical observations over a period of five years. To allow more accurate astronomical observations and recordings, Shen Kuo improved the technical designs of the rotating armillary sphere
, the gnomon
, the clepsydra
clock
, and the sighting tube. Shen Kuo calibrated the standard diameter of the sighting tube's width, hence allowing the observation of the polestar indefinitely (which had shifted since the time of Zu Geng in the 5th century). With these, Shen and Wei attempted to predict the mean speeds of the planets as well as the accurate positions of the planets in their orbits. They established a system of observing and recording on a star map the exact coordinates of the planets, done three times a night for a total of five years. Shen Kuo made a cosmological hypotheses in explaining the variations of planetary motions, including the concept of retrogradation
. On the other hand, Wei Pu realized that the old calculation technique for the mean sun was inaccurate compared to the apparent sun, since the latter was ahead of it in the accelerated phase of motion, and behind it in the retarded phase. Hence, he incorporated solar motion into the eclipse
theory.
The Song Dynasty astronomers of Wei's day still retained the lunar theory and coordinates of the earlier Yi Xing
(683
-727
AD), which after 350 years had devolved into a state of considerable error. To fix this, Shen and Wei kept similar astronomical records, three times a night over five years, for the orbital path of the moon. Wei and Shen's work was deeply opposed by the officials and fellow astronomers at court, who were offended by their insistence that the coordinates of the renowned Yi Xing were inaccurate. The elite, well-educated ministers and leading astronomers were also insulted by the fact that Wei Pu was born a commoner, yet held more expertise in his field than many of them. When Wei and Shen made a public demonstration using the gnomon to prove the doubtful wrong, the other ministers reluctantly agreed to correct the lunar error. Although correcting the lunar error was a success, the other ministers and officials eventually dismissed Wei and Shen's recorded course plotting of planetary motions, while the court relied upon the inefficient and older model. This meant that only the very worst errors were corrected for planetary motion, and in his disappointment, Shen wrote, "How sad that the backbiting of that bunch of calendar-makers could have kept him from bringing his art to fruition!"
History of China
Chinese civilization originated in various regional centers along both the Yellow River and the Yangtze River valleys in the Neolithic era, but the Yellow River is said to be the Cradle of Chinese Civilization. With thousands of years of continuous history, China is one of the world's oldest...
astronomer
Astronomer
An astronomer is a scientist who studies celestial bodies such as planets, stars and galaxies.Historically, astronomy was more concerned with the classification and description of phenomena in the sky, while astrophysics attempted to explain these phenomena and the differences between them using...
of the Song Dynasty
Song Dynasty
The Song Dynasty was a ruling dynasty in China between 960 and 1279; it succeeded the Five Dynasties and Ten Kingdoms Period, and was followed by the Yuan Dynasty. It was the first government in world history to issue banknotes or paper money, and the first Chinese government to establish a...
(960
960
Year 960 was a leap year starting on Sunday of the Julian calendar.- Europe :* Edgar the Peaceable is crowned King of England. Dunstan becomes Archbishop of Canterbury and Edgar's chief adviser. He reforms monasteries and enforces the rule of Saint Benedict: Poverty, Chastity and Obedience for...
-1279 AD). He was born a commoner, but eventually rose to prominence as an astronomer working for the imperial court at the capital of Kaifeng
Kaifeng
Kaifeng , known previously by several names , is a prefecture-level city in east-central Henan province, Central China. Nearly 5 million people live in the metropolitan area...
. Wei became a trusted colleague of the famous statesman and scientist Shen Kuo
Shen Kuo
Shen Kuo or Shen Gua , style name Cunzhong and pseudonym Mengqi Weng , was a polymathic Chinese scientist and statesman of the Song Dynasty...
(1031-1095 AD), who served as the head official for the Bureau of Astronomy, and worked on various projects with Wei Pu.
Achievements at court
When Shen Kuo became the Supervisor of the Directorate of Astronomy in 1072 AD, Wei Pu became Shen's protege, and was eager to partake in Shen's ideal reforms to the Chinese calendarChinese calendar
The Chinese calendar is a lunisolar calendar, incorporating elements of a lunar calendar with those of a solar calendar. It is not exclusive to China, but followed by many other Asian cultures as well...
system. With the aid of many different scholars and a large assortment of gathered books written on astronomy, Shen and Wei embarked on this enormous project. With the aid of Wei Pu, Shen planned to make a series of nightly astronomical observations over a period of five years. To allow more accurate astronomical observations and recordings, Shen Kuo improved the technical designs of the rotating armillary sphere
Armillary sphere
An armillary sphere is a model of objects in the sky , consisting of a spherical framework of rings, centred on Earth, that represent lines of celestial longitude and latitude and other astronomically important features such as the ecliptic...
, the gnomon
Gnomon
The gnomon is the part of a sundial that casts the shadow. Gnomon is an ancient Greek word meaning "indicator", "one who discerns," or "that which reveals."It has come to be used for a variety of purposes in mathematics and other fields....
, the clepsydra
Clepsydra
Clepsydra may refer to:*Clepsydra , the Greek word for water clock. Also, in ancient Greece, a device for drawing liquids from vats too large to pour, which utilized the principles of air pressure to transport the liquid from one container to another.* Clepsydra Geyser in the Lower Geyser Basin of...
clock
Clock
A clock is an instrument used to indicate, keep, and co-ordinate time. The word clock is derived ultimately from the Celtic words clagan and clocca meaning "bell". A silent instrument missing such a mechanism has traditionally been known as a timepiece...
, and the sighting tube. Shen Kuo calibrated the standard diameter of the sighting tube's width, hence allowing the observation of the polestar indefinitely (which had shifted since the time of Zu Geng in the 5th century). With these, Shen and Wei attempted to predict the mean speeds of the planets as well as the accurate positions of the planets in their orbits. They established a system of observing and recording on a star map the exact coordinates of the planets, done three times a night for a total of five years. Shen Kuo made a cosmological hypotheses in explaining the variations of planetary motions, including the concept of retrogradation
Retrogradation
Retrogradation is the term for the landward change in position of the front of a river delta with time. This occurs when the mass balance of sediment into the delta is such that the volume of incoming sediment is less than the volume of the delta that is lost through subsidence, sea-level rise,...
. On the other hand, Wei Pu realized that the old calculation technique for the mean sun was inaccurate compared to the apparent sun, since the latter was ahead of it in the accelerated phase of motion, and behind it in the retarded phase. Hence, he incorporated solar motion into the eclipse
Eclipse
An eclipse is an astronomical event that occurs when an astronomical object is temporarily obscured, either by passing into the shadow of another body or by having another body pass between it and the viewer...
theory.
The Song Dynasty astronomers of Wei's day still retained the lunar theory and coordinates of the earlier Yi Xing
Yi Xing
Yi Xing , born Zhang Sui , was a Chinese astronomer, mathematician, mechanical engineer,and Buddhist monk of the Tang Dynasty...
(683
683
Year 683 was a common year starting on Thursday of the Julian calendar. The denomination 683 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years.- America :* The reign of Pacal the Great, ruler of...
-727
727
Year 727 was a common year starting on Wednesday of the Julian calendar. The denomination 727 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years.- Byzantine Empire :* Umayyad troops under Abdallah...
AD), which after 350 years had devolved into a state of considerable error. To fix this, Shen and Wei kept similar astronomical records, three times a night over five years, for the orbital path of the moon. Wei and Shen's work was deeply opposed by the officials and fellow astronomers at court, who were offended by their insistence that the coordinates of the renowned Yi Xing were inaccurate. The elite, well-educated ministers and leading astronomers were also insulted by the fact that Wei Pu was born a commoner, yet held more expertise in his field than many of them. When Wei and Shen made a public demonstration using the gnomon to prove the doubtful wrong, the other ministers reluctantly agreed to correct the lunar error. Although correcting the lunar error was a success, the other ministers and officials eventually dismissed Wei and Shen's recorded course plotting of planetary motions, while the court relied upon the inefficient and older model. This meant that only the very worst errors were corrected for planetary motion, and in his disappointment, Shen wrote, "How sad that the backbiting of that bunch of calendar-makers could have kept him from bringing his art to fruition!"
Further reading
- Needham, Joseph (1986). Science and Civilization in China: Volume 3, Mathematics and the Sciences of the Heavens and the Earth. Taipei: Caves Books Ltd.