Wei Pu (; Wade-Giles: Wei P'u) was a Chinese

astronomer An astronomer is a scientist in the field of astronomy who focuses their studies on a specific question or field outside the scope of Earth. They observe astronomical objects such as stars, planets, moons, comets and galaxies – in either ...

and politician of the

Song Dynasty The Song dynasty (; ; 960–1279) was an imperial dynasty of China that began in 960 and lasted until 1279. The dynasty was founded by Emperor Taizu of Song following his usurpation of the throne of the Later Zhou. The Song conquered the rest ...

(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 Kaifeng () is a prefecture-level city in east-central Henan province, China. It is one of the Eight Ancient Capitals of China, having been the capital eight times in history, and is best known for having been the Chinese capital during the No ...

.Sivin, III, 6. Wei became a trusted colleague of the famous Song polymath 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.

Achievements at court

When Shen Kuo became the Supervisor of the Directorate of Astronomy in 1072 AD, Wei Pu became Shen's protégé, and was eager to partake in Shen's ideal reforms to the Chinese calendar 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 A clock or a timepiece is a device used to measure and indicate time. The clock is one of the oldest human inventions, meeting the need to measure intervals of time shorter than the natural units such as the day, the lunar month and t ...

, and the sighting tube.Sivin, III, 17. Shen Kuo calibrated the standard diameter of the sighting tube's width, hence allowing the observation of the

pole star A pole star or polar star is a star, preferably bright, nearly aligned with the axis of a rotating astronomical body. Currently, Earth's pole stars are Polaris (Alpha Ursae Minoris), a bright magnitude-2 star aligned approximately with its ...

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.Sivin, III, 18. 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 Cosmology () is a branch of physics and metaphysics dealing with the nature of the universe. The term ''cosmology'' was first used in English in 1656 in Thomas Blount's ''Glossographia'', and in 1731 taken up in Latin by German philosopher ...

hypotheses in explaining the variations of

planetary motion In celestial mechanics, an orbit is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an object or position in space such as a ...

s, including the concept of retrogradation.Sivin, III, 16. 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.Sivin, III, 19. 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 Tang astronomer, mathematician, and mechanical engineer

Yi Xing Yi Xing (, 683–727), born Zhang Sui (), was a Chinese astronomer, Buddhist monk, inventor, mathematician, mechanical engineer, and philosopher during the Tang dynasty. His astronomical celestial globe featured a liquid-driven escapement, the ...

(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.Sivin, III, 18-19. 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.Sivin, II, 73. 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.Sivin, III, 7. 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!"

Notes

References

* Sivin, Nathan (1995). ''Science in Ancient China: Researches and Reflections''. Brookfield, Vermont: VARIORUM, Ashgate Publishing.

External links

The complete chapter on Shen Kuo in Nathan Sivin's book
{{DEFAULTSORT:Wei, Pu Year of death unknown Year of birth unknown 11th-century Chinese astronomers Song dynasty politicians

Achievements at court

See also

Notes

References

Further reading

External links