Zhang Yuzhe (; 16 February 1902 – 21 July 1986), also known as Yu-Che Chang, 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 obse ...

and director of the Purple Mountain Observatory who is widely regarded as the father of modern Chinese astronomy. accessed 3 October 2006 He studied the

light curves In astronomy, a light curve is a graph of light intensity of a celestial object or region as a function of time, typically with the magnitude of light received on the y axis and with time on the x axis. The light is usually in a particular frequ ...

of asteroids, and thus their

rotation period The rotation period of a celestial object (e.g., star, gas giant, planet, moon, asteroid) may refer to its sidereal rotation period, i.e. the time that the object takes to complete a single revolution around its axis of rotation relative to the ...

s. He also researched the variable star CZ Cassiopeiae and the evolution of the orbit of

Comet Halley Halley's Comet or Comet Halley, officially designated 1P/Halley, is a short-period comet visible from Earth every 75–79 years. Halley is the only known short-period comet that is regularly visible to the naked eye from Earth, and thus the on ...

. Zhang discovered 3

comet A comet is an icy, small Solar System body that, when passing close to the Sun, warms and begins to release gases, a process that is called outgassing. This produces a visible atmosphere or coma, and sometimes also a tail. These phenomena are ...

s and is credited under the name Y. C. Chang by the Minor Planet Center for the discovery of one

minor planet According to the International Astronomical Union (IAU), a minor planet is an astronomical object in direct orbit around the Sun that is exclusively classified as neither a planet nor a comet. Before 2006, the IAU officially used the term ''mino ...

, the outer main-belt asteroid

3789 Zhongguo 3789 Zhongguo, provisional designation ', is a resonant asteroid from outermost region of the asteroid belt, approximately in diameter. It was discovered in 1928 by Chinese astronomer Zhang Yuzhe at the Yerkes Observatory in Williams Bay, Wiscon ...

Biography

Zhang was born in Minhou,

Fujian province Fujian (; alternately romanized as Fukien or Hokkien) is a province on the southeastern coast of China. Fujian is bordered by Zhejiang to the north, Jiangxi to the west, Guangdong to the south, and the Taiwan Strait to the east. Its ...

in 1902. In 1919, he gained entrance to

Tsinghua University Tsinghua University (; abbr. THU) is a national public research university in Beijing, China. The university is funded by the Ministry of Education. The university is a member of the C9 League, Double First Class University Plan, Project ...

. Graduating in 1923, he traveled to the United States where he began graduate studies at the University of Chicago in 1925, receiving his Ph.D. in 1929. Later that year, he returned to China and accepted a teaching post at the National Central University in Nanjing, China (now known as Nanjing University). While pursuing his Ph.D. at the University of Chicago in 1928, Zhang discovered an

asteroid An asteroid is a minor planet of the inner Solar System. Sizes and shapes of asteroids vary significantly, ranging from 1-meter rocks to a dwarf planet almost 1000 km in diameter; they are rocky, metallic or icy bodies with no atmosphere. ...

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" as it was not observed beyond its initial appearance and a precise orbit could not be calculated (see

lost asteroids A minor planet is "lost" when today's observers cannot find it, because its location is too uncertain to target observations. This happens if the orbital elements of a minor planet are not known accurately enough, typically because the observat ...

). In 1957, while Zhang was director of the Purple Mountain Observatory in China, the observatory discovered a new asteroid. With his agreement the new object was reassigned the official designation 1125 China in place of the lost 1928 UF. However, in 1986, the newly discovered object was confirmed to be a rediscovery of the original 1928 UF, and this object was named

("中国" (''Zhōngguó'') is the Mandarin Chinese word for "China", in pinyin transliteration, whereas ''Zhōnghuá'' is a slightly older word for "China"). From 1941 to 1950, Zhang was head of the astronomy research institute at National Central University. Between 1946 and 1948, he returned to the United States to study variable stars. In 1950 Zhang became the director of the Purple Mountain Observatory, a position he held until 1984. In 1955 he was elected a founding academician of the

Chinese Academy of Sciences The Chinese Academy of Sciences (CAS); ), known by Academia Sinica in English until the 1980s, is the national academy of the People's Republic of China for natural sciences. It has historical origins in the Academia Sinica during the Republ ...

. Zhang 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 60P/Tsuchinshan, also known as Tsuchinshan 2, is a periodic comet in the Solar System with an orbital period of 6.79 years. Tsuchinshan is the Wade-Giles transliteration corresponding to the pinyin ''Zĭjīn Shān'', which is Mandarin Chinese f ...

(Tsuchinshan 2) and

62P/Tsuchinshan 62P/Tsuchinshan, also known as Tsuchinshan 1, is a periodic comet discovered on 1965 January 1 at Purple Mountain Observatory, Nanking. It will next come to perihelion on 25 December 2023 at around apparent magnitude 8, and will be from Earth ...

(Tsuchinshan 1), and one non-periodic, C/1977 V1. ''Tsuchinshan'' is the Wade-Giles transliteration corresponding to the pinyin ''Zĭjīn Shān'', which is Mandarin Chinese for "Purple Mountain", named after the observatory he oversaw. The lunar crater ''

Zhang Yuzhe Zhang Yuzhe (; 16 February 1902 – 21 July 1986), also known as Yu-Che Chang, was a Chinese astronomer and director of the Purple Mountain Observatory who is widely regarded as the father of modern Chinese astronomy. accessed 3 October 2006 He ...

'' and the main-belt asteroid 2051 Chang are named after him.

References

{{DEFAULTSORT:Zhang, Yuzhe 1902 births 1986 deaths 20th-century astronomers Boxer Indemnity Scholarship recipients Chinese astronomers Educators from Fujian Discoverers of asteroids Discoverers of comets Members of the Chinese Academy of Sciences Nanjing University faculty National Central University faculty People from Fuzhou Scientists from Fujian Tsinghua University alumni University of Chicago alumni Directors of the Purple Mountain Observatory