Yi Xing

Yi Xing (* 683 ; † 727 , Chinese 一行 , Pinyin Yīxíng , W.-G. I Hsing ) was a Chinese astronomer , mathematician , engineer and Buddhist monk during the Tang Dynasty (618-907). His monk name can equally mean “whole journey” or “the all-capable”. His worldly name was Zhāng Suì ( 張遂 / 张遂 ).

technology

He built a water-powered armillary sphere controlled by a balance wheel, the parts of which rotated automatically at different speeds with a common drive. The fastest gear moved by 2,928 teeth a day, the slowest by one tooth every five days. His masterpiece was a further development of similar devices that had been constructed in China since the 2nd century AD.

Measurements

Faced with the task of improving the calendar, but especially of predicting parallaxes, i.e. solar and lunar eclipses , he set up a system of twenty observatories, ten of which are distributed near the 114th degree of longitude (according to today's Greenwich date ) from the 17th parallel in Jiaozhou in Vietnam to the 50th parallel on Lake Baikal . His calendar work, calculated on the basis of the measurements, comprised seven volumes.

In Gaocheng , the site of one of his observatories, a larger one was built in the 11th century, followed by a new one in the 13th century under Kubilai Khan , the only one from ancient China that still exists today.

Discoveries

Yi Xing's value for the distance between the latitudes and thus the circumference of the earth was 11.4% above the actual one, 123.7 km instead of 111 km.

He realized that solar and lunar eclipses did not affect the entire globe, but had to occur at different times in different parts of the world.

He discovered the proper movement of the fixed stars , i.e. the change in the angles at which they can be seen from the earth. So he came to the realization that they could not sit on a spherical shell, as had been assumed in China until then.

Appreciation

The asteroid (1972) was named Yi Xing after Yi Xing .

Web links

personal data
SURNAME	Yi, Xing
ALTERNATIVE NAMES	I, Hsing; 一行 (Chinese); Yī, Xíng
BRIEF DESCRIPTION	Chinese astronomer, mathematician, engineer and Buddhist monk
DATE OF BIRTH	683
DATE OF DEATH	727