Zhang Yuzhe

Zhang Yuzhe or Yu-Che Chang (zh-tspw |t=張鈺哲|s=张钰哲|p=Zhāng Yùzhé|w=Chang Yu-che) (16 February 1902 – 21 July 1986) was a Chinese astronomer who is widely regarded as the father of modern Chinese astronomy [http://adsabs.harvard.edu/abs/1987S&T....73Q.481. accessed 3 October 2006] .

He was born in Minhou, Fujian province. In 1919, he entered Tsinghua University and graduated in 1923. That same year he went to the United States and, in 1925, entered the University of Chicago and got his Ph.D. in 1929. That same year he returned to China and took up a teaching post at National Central University.

While studying in Chicago in 1928, he discovered an asteroid, which was given the provisional designation 1928 UF and later the number 1125. He named it "China" or "中華" ("Zhōnghuá"). However, this asteroid was "lost", that is, it was not observed beyond its initial appearance and a precise orbit could not be calculated. In 1957, the Purple Mountain Observatory in China discovered a new asteroid, and with his agreement the new object mp|1957 UN|1 was re-assigned the official designation 1125 China in place of the lost 1928 UF. However, in 1986, the newly discovered object mp|1986 QK|1 was confirmed to be a rediscovery of the original 1928 UF, and this object was named 3789 Zhongguo. Note "中国" ("Zhōngguó") is the Mandarin Chinese word for "China", in pinyin transliteration, and "Zhōnghuá" is a slightly older word for "China".

From 1941 to 1950, he was head of the astronomy research institute at National Central University. From 1946 to 1948, he once again went to the United States to study variable stars. From 1950 to 1984, he was director of Purple Mountain Observatory, and, from 1955 on, he was a member of the Chinese Academy of Sciences.

He devoted himself to observing and calculating the orbits of minor planets and comets. Many asteroids were discovered at Purple Mountain Observatory, as well as three new comets: two periodic, 60P/Tsuchinshan (Tsuchinshan 2) and 62P/Tsuchinshan (Tsuchinshan 1), and one not, C/1977 V1. The name "Tsuchinshan" is an obsolete transliteration corresponding to the modern pinyin "Zĭjīn Shān", which is Mandarin Chinese for "Purple Mountain".

He studied the light curves of asteroids and thus their rotation, and also studied the variable star CZ Cassiopeiae, and the evolution of the orbit of Comet Halley.

Zhang Yuzhe is credited by the Minor Planet Center for the discovery of 3789 Zhongguo under the name "Y. C. Chang". The asteroid 2051 Chang is named after him.

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