'''Wei Pu''' ({{zh|t=衛朴}}; Wade-Giles: '''Wei P'u''') was a Chinese astronomer and politician of the Northern Song dynasty. He was born a commoner, but eventually rose to prominence as an astronomer working for the imperial court at the capital of Kaifeng.<ref name="sivin III 6">Sivin, III, 6.</ref> Wei became a trusted colleague of the famous Northern Song polymath statesman and scientist Shen Kuo, 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.<ref name="sivin III 6"/> 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.<ref name="sivin III 6"/> With the aid of Wei Pu, Shen planned to make a series of nightly astronomical observations over a period of five years.<ref name="sivin III 6"/> 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.<ref name="sivin III 17">Sivin, III, 17.</ref> Shen Kuo calibrated the standard diameter of the sighting tube's width, hence allowing the observation of the pole star indefinitely (which had shifted since the time of Zu Geng in the 5th century).<ref name="sivin III 17"/> 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.<ref name="sivin III 18">Sivin, III, 18.</ref> 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.<ref name="sivin III 18"/> Shen Kuo made a cosmological hypotheses in explaining the variations of planetary motions, including the concept of retrogradation.<ref name="sivin III 16">Sivin, III, 16.</ref> 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.<ref name="sivin III 19">Sivin, III, 19.</ref> Hence, he incorporated solar motion into the eclipse theory.<ref name="sivin III 19"/>
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 (683-727 AD), which after 350 years had devolved into a state of considerable error.<ref name="sivin III 18"/> To fix this, Shen and Wei kept similar astronomical records, three times a night over five years, for the orbital path of the moon.<ref name="sivin III 18"/> 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.<ref name="sivin III 18 19">Sivin, III, 18-19.</ref> 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.<ref name="sivin II 73">Sivin, II, 73.</ref> 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.<ref name="sivin III 18 19"/> 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.<ref name="sivin III 7">Sivin, III, 7.</ref> 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!"<ref name="sivin II 73"/>
==See also== *Science and technology of the Song Dynasty
==Notes==
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==References== *Sivin, Nathan (1995). ''Science in Ancient China: Researches and Reflections''. Brookfield, Vermont: VARIORUM, Ashgate Publishing.
==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.
==External links== *[http://ccat.sas.upenn.edu/~nsivin/shen.pdf The complete chapter on Shen Kuo in Nathan Sivin's book] {{Song dynasty topics}} {{DEFAULTSORT:Wei, Pu}} Category:Year of death unknown Category:Year of birth unknown Category:11th-century Chinese astronomers Category:Song dynasty government officials