Yuzhe ZHANG(Y.C. Chang) (1902-1986) was a Chinese astronomer who is widely regarded as the father of modern Chinese astronomy. He served as the president of the Chinese Astronomical Society for more than 40 years (1943-1985). He was born in Minhou, Fujian Province. In 1919, he entered Tsinghua University, and continued his study in USA later. He firstly studied engineering at Purdue University and architecture at Cornell University, and changed to astronomy at Chicago University finally. In 1928 he discovered No. 1125 asteroid which he named as 'China'. In 1929, he got his PhD degree and returned to China in the same year. He taught at Physics Department of the National Central University, and was appointed as the director of the Astronomical Institute of the former Academia Sinica in 1941. In 1941, he successfully organized a team who made a total solar eclipse observation in Gansu province. They risked their lifes to do observations under the Japanese air raids all the way.
During 1946-1948, he visited USA and worked on eclipsing binary spectrum. After 1949, as the director of Purple Mountain Observatory (director emeritus since Feb. 1984), he made great contributions to the observation of the light variation periods of asteroids by photoelectric photometry. He discovered a number of asteroids which were not numbered on the Ephemeris before and three comets was named by him as 'Tsuchinshan' (Purple Mountain). He was elected as a member of Chinese Academy of Sciences (academician) in 1956. He published 'Photoelectric Photometry of the Variable Minor Planets', 'Orbital Evolution and Its History of Halley's Comet', and other books and papers.
In 1957, Yuzhe Zhang studied the orbit of artificial satellites which is the basis of the theory of satellites in our country. In the 1960s he and his group were involved in the project of calculation and design of orbit of the first satellite of China, which was a great success and they made great contribution. They have made more than 8000 reliable observations of asteroids in total, and discovered more than 1000 new asteroids. To memorialize him, Zhang Yuzhe is credited by the Minor Planet Center for the discovery of 3789 Zhongguo under the name 'Y. C. Chang', and the asteroid No. 2051 Chang is named after him.