Liu Hong (129–210),

courtesy name A courtesy name ( zh, s=字, p=zì, l=character), also known as a style name, is an additional name bestowed upon individuals at adulthood, complementing their given name. This tradition is prevalent in the East Asian cultural sphere, particula ...

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

Eastern Han dynasty The Han dynasty was an Dynasties of China, imperial dynasty of China (202 BC9 AD, 25–220 AD) established by Liu Bang and ruled by the House of Liu. The dynasty was preceded by the short-lived Qin dynasty (221–206 BC ...

. He developed a work on predicting the passage of the

moon The Moon is Earth's only natural satellite. It Orbit of the Moon, orbits around Earth at Lunar distance, an average distance of (; about 30 times Earth diameter, Earth's diameter). The Moon rotation, rotates, with a rotation period (lunar ...

which was in use during the

Three Kingdoms The Three Kingdoms of Cao Wei, Shu Han, and Eastern Wu dominated China from AD 220 to 280 following the end of the Han dynasty. This period was preceded by the Eastern Han dynasty and followed by the Jin dynasty (266–420), Western Jin dyna ...

period of China.

Life

Liu Hong was from Mengyin County (), Taishan Commandery, which is present-day Mengyin County,

Shandong Shandong is a coastal Provinces of China, province in East China. Shandong has played a major role in Chinese history since the beginning of Chinese civilization along the lower reaches of the Yellow River. It has served as a pivotal cultural ...

, 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 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, 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 which 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 ...

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 language, Chinese: 吳; pinyin: ''Wú''; Middle Chinese *''ŋuo'' < Eastern Han Chinese: ''*ŋuɑ''), known in historiography as Eastern Wu or Sun Wu, was a Dynasties of China, dynastic state of China and one of the three major sta ...

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 (; 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 organization. A nuncio is ...

(), ''gucheng menhou'' (), Commandant of the East District of Kuaiji (), Administrator of Shanyang () and Chancellor of Qucheng ().

References

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