Liu Hong (129–210),

courtesy name A courtesy name (), also known as a style name, is a name bestowed upon one at adulthood in addition to one's given name. This practice is a tradition in the East Asian cultural sphere, including China, Japan, Korea, and Vietnam.Ulrich Theobald ...

Yuanzhuo, was a Chinese astronomer, mathematician, and politician who lived in the late

Eastern Han dynasty The Han dynasty (, ; ) was an imperial dynasty of China (202 BC – 9 AD, 25–220 AD), established by Liu Bang (Emperor Gao) and ruled by the House of Liu. The dynasty was preceded by the short-lived Qin dynasty (221–207 BC) and a warr ...

. He developed a work on predicting the passage of the

moon The Moon is Earth's only natural satellite. It is the fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth (comparable to the width of ...

which was in use during the

Three Kingdoms The Three Kingdoms () from 220 to 280 AD was the tripartite division of China among the dynastic states of Cao Wei, Shu Han, and Eastern Wu. The Three Kingdoms period was preceded by the Han dynasty#Eastern Han, Eastern Han dynasty and wa ...

period of China.

Life

Liu Hong was from Mengyin County (),

Taishan Commandery Taishan Commandery ( zh, 泰山郡) was a historical commandery of China in present-day Shandong province, existing from Han dynasty to Sui dynasty. Taishan Commandery was created in 122 BC, when the king of Jibei offered the land surrounding Moun ...

, which is present-day

Mengyin County Mengyin County () is a county in the southwest-central part of Shandong province, People's Republic of China. It is under the administration of Linyi Linyi () is a prefecture-level city in the south of Shandong province, China. As of 2011, ...

Shandong Shandong ( , ; ; alternately romanized as Shantung) is a coastal province of the People's Republic of China and is part of the East China region. Shandong has played a major role in Chinese history since the beginning of Chinese civilizati ...

, and was a descendant of Liu Yu, the Prince of Lu, a son of Emperor Jing ( 157–141 BCE). He developed an interest in astronomy at an early age. He was made an officer at the Imperial Astronomy around 160 CE which led to him writing the lost works ''Qi Yao Shu'' (七曜術; ''The Art of the Seven Planets'') and ''Ba Yuan Shu'' (八元術; ''The Art of Eight Elements''). After the death of his father, Liu Hong retired for a short time but then returned to his work, collaborating with

Cai Yong Cai Yong (Chinese: ; 132–192), courtesy name Bojie, was Chinese astronomer, calligrapher, historian, mathematician, musician, politician, and writer of the Eastern Han dynasty. He was well-versed in calligraphy, music, mathematics and astrono ...

on the ''Qian Xiang Li'' (乾象曆; ''Qian Xiang Calendar''). This was considered so advanced for its time that it was adopted by the Han government immediately. The calendar predicted the movement of the moon, the first time such considerations had been made in China. This system marked the first appearance of the

argument of periapsis The argument of periapsis (also called argument of perifocus or argument of pericenter), symbolized as ''ω'', is one of the orbital elements of an orbiting body. Parametrically, ''ω'' is the angle from the body's ascending node to its periapsi ...

, a means to calculate the syzygy (the calculation between three celestial bodies), and a means of charting the moon through the seasons. His means of establishing the accuracy of the calendar was by the detection of

eclipse An eclipse is an astronomical event that occurs when an astronomical object or spacecraft is temporarily obscured, by passing into the shadow of another body or by having another body pass between it and the viewer. This alignment of three ce ...

s. This system replaced one which had been used by the Han dynasty since 85 CE, and following the end of the Han dynasty and beginning of the

period, it was adopted by the

Eastern Wu Wu ( Chinese: 吳; pinyin: ''Wú''; Middle Chinese *''ŋuo'' <

Eastern Han Chinese

: ''*ŋuɑ''), known in h ...

state until China was re-unified under the Jin dynasty in 280 CE. In 179 CE, he was asked by the Imperial Secretariat to consider proposals made by a private scholar called Wang Han regarding lunar calendars, but he did not support those proposals. A year later, the Minister of Ceremonies assigned him to review alternative means of calculating eclipses. Throughout his service under the Han government, Liu Hong held various positions, including:

Internuncio An apostolic nuncio ( la, nuntius apostolicus; also known as a papal nuncio or simply as a nuncio) is an ecclesiastical diplomat, serving as an envoy or a permanent diplomatic representative of the Holy See to a state or to an international o ...

(), ''gucheng menhou'' (), Commandant of the East District of

Kuaiji Shaoxing (; ) is a prefecture-level city on the southern shore of Hangzhou Bay in northeastern Zhejiang province, China. It was formerly known as Kuaiji and Shanyin and abbreviated in Chinese as (''Yuè'') from the area's former inhabitants. ...

(), Administrator of Shanyang () and Chancellor of Qucheng ().

References

{{DEFAULTSORT:Liu, Hong 129 births 210 deaths 2nd-century Chinese mathematicians 3rd-century Chinese mathematicians Ancient Chinese astronomers Ancient Chinese mathematicians Han dynasty politicians from Shandong Mathematicians from Shandong Politicians from Linyi