Chinese astronomy

Astronomy in China has a long history stretching from the Shang dynasty, being refined over a period of more than 3,000 years. The ancient Chinese people have identified stars from 1300 BCE, as Chinese star names later categorized in the twenty-eight mansions have been found on oracle bones unearthed at Anyang, dating back to the mid-Shang dynasty. The core of the "mansion" system also took shape around this period, by the time of King Wu Ding.
Detailed records of astronomical observations began during the Warring States period. They flourished during the Han period and subsequent dynasties with the publication of star catalogues. Chinese astronomy was equatorial, centered on close observation of circumpolar stars, and was based on different principles from those in traditional Western astronomy, where heliacal risings and settings of zodiac constellations formed the basic ecliptic framework. Joseph Needham has described the ancient Chinese as the most persistent and accurate observers of celestial phenomena anywhere in the world before the Islamic astronomers.
Some elements of Indian astronomy reached China with the expansion of Buddhism after the Eastern Han dynasty, but most incorporation of Indian astronomical thought occurred during the Tang dynasty, when numerous Indian astronomers took up residence in the Chinese capital Chang'an, and Chinese scholars, such as the Tantric Buddhist monk and mathematician Yi Xing, mastered the Indian system. Islamic astronomers collaborated closely with their Chinese colleagues during the Yuan dynasty, and, after a period of relative decline during the Ming dynasty, astronomy was revitalized under the stimulus of Western cosmology and technology after the Jesuits established their missions. The telescope was introduced from Europe in the seventeenth century. In 1669, the Peking observatory was completely redesigned and refitted under the direction of Ferdinand Verbiest. Today, China continues to be active in the field of astronomy, with many observatories and its own space program.

Early history

Purpose of astronomical observations in the past

One of the main functions of astronomy was for the purpose of timekeeping. The Chinese used a lunisolar calendar, but as the cycles of the Sun and the Moon are different, leap months had to be inserted regularly. The Chinese calendar was considered to be a symbol of a dynasty. As dynasties would rise and fall, astronomers and astrologers of each period would often prepare a new calendar, making observations for that purpose.
Astrological divination was also an important part of astronomy. Astronomers took note of "guest stars", usually supernovas or comets, which appear among the fixed stars. The supernova which created the Crab Nebula, now known as SN 1054, is an example of an astronomical event observed by Ancient Chinese astronomers. Ancient astronomical records of phenomena like comets and supernovae are sometimes used in modern astronomical studies.

Cosmology

The Chinese developed multiple cosmological models before Western influences changed the field:

Gai Tian – The sky is a hemisphere, the Earth is a disc at the bottom, surrounded by water, which rotates around the North Pole once a day. The Sun traces a circle in the hemisphere, the size of which varies with the seasons. As described in the Zhoubi Suanjing.
Hun Tian – Similar to Gai Tian, but the sky is a full sphere. The seasons are explained by the North Pole shifting rather than remaining directly overhead.
Shuen Ye, ''Xuan Ye, or Suan Ye – The heavens are infinite in extent, the celestial bodies are floating about on their own'' at rare intervals, and "the speed of the luminaries depends on their individual natures, which shows they are not attached to anything." Very few pieces of information are known about this school of thought.''''
Constellations

The divisions of the sky began with the Northern Dipper and the 28 mansions. In 1977, a lacquer box was excavated from the Tomb of Marquis Yi of Zeng, in Suixian, Hubei Province. Names of the 28 lunar mansions were found on the cover of the box, proving that the use of this classification system was made before 433 BCE.
As lunar mansions have such an ancient origin, the meanings of most of their names have become obscure. Contributing to later confusion, the name of each lunar mansion consists of only one Chinese word, the meaning of which could vary at different times in history. The meanings of the names are still under discussion.
Besides the 28 lunar mansions, most constellations are based on the works of Shi Shen-fu and Gan De, who were astrologists during the period of the Warring States in China. In his Shiji, the Western Han era historian Sima Qian provided a star catalogue that includes 90 constellations. The Eastern Han era polymath scientist and inventor Zhang Heng published a star catalogue in 120 CE that features 124 recorded constellations. In the late period of the Ming dynasty, the agricultural scientist and mathematician Xu Guangqi introduced 23 additional constellations near to the Celestial South Pole, which are based on star catalogues from the Western world introduced by his colleague, the Italian Jesuit Matteo Ricci.

Star catalogues and maps

Star catalogues

In the fourth century BCE, the two Chinese astronomers responsible for the earliest information going into the star catalogues were Shi Shen and Gan De of the Warring States period.

Author	Translated name	Chinese catalogue name	Pinyin
Shi Shen	Shi Shen astronomy	石申天文	Shi Shen tianwen
Gan De	Astronomic star observation	天文星占	Tianwen xingzhan

These books appeared to have lasted until the sixth century, but were lost after that. A number of books share similar names, often quoted and named after them. These texts should not be confused with the original catalogues written by them. Notable works that helped preserve the contents include:

Author	Translated name	Chinese name	Pinyin	Comments
Sima Qian	Book of Celestial Offices	天官書	Tianguan shu	This is the astronomical chapter of the Records of the Grand Historian, a massive history compiled during the late 2nd century BCE by the Han-era scholar and official Sima Qian. This chapter provides a star catalogue and discusses the schools of Gan De and Shi Shen.
Ma Xian	Star Manual of the Masters Gan and Shi	甘石星經	Gan Shi Xingjing	Despite having the name credited to Shi and Gan, it was lost and later compiled circa 579 CE as an appendix to the Treatise on Astrology of the Kaiyuan Era, and summarized in the book 郡齋讀書志.
	Book of Jin	晉書	Jin shu	In the astronomical chapters of the text
	Book of Sui	隋書	Sui shu
Gautama Siddha	Treatise on Astrology of the Kaiyuan Era	開元占經	Kaiyuan Zhanjing	During the reign of Emperor Xuanzong of Tang. After analyzing and providing a summary on the work of Gan De and Shi Shen, Tang era astronomers mentioned the names of more than 800 stars that were found, 121 of them marked with positions. The astronomical table of sines by the Indian astronomer and mathematician Aryabhata were also translated into the Kaiyuan Zhanjing.
	The Great Firmament Star Manual Common to Astrology	通占大象曆星經	Tongzhan taxiangli xingjing	This renamed star manual is incorporated in the Taoist book Daozang.

Wu Xian has been one of the astronomers under debate. He is often represented as one of the "Three Schools Astronomical tradition", along with Gan and Shi. The Chinese classic text Star Manual of Master Wu Xian and its authorship is still in dispute, because it mentioned names of twelve countries that did not exist in the Shang dynasty, the era in which it was supposed to have been written. Moreover, it was customary in the past for the Chinese to forge works of notable scholars, as this could lead to a possible explanation for the inconsistencies found. Wu Xian is generally mentioned as the astronomer who lived many years before Gan and Shi.
The Han dynasty astronomer and inventor Zhang Heng not only catalogued some 2500 different stars, but also recognized more than 100 different constellations. Zhang Heng also published his work Ling Xian, a summary of different astronomical theories in China at the time. In the subsequent period of the Three Kingdoms, Chen Zhuo combined the work of his predecessors, forming another star catalogue. This time, 283 constellations and 1464 stars were listed. The astronomer Guo Shoujin of the Yuan dynasty created a new catalogue, which was believed to contain thousands of stars. Unfortunately, many of the documents of that period were destroyed, including that of Shoujin. Imperial Astronomical Instruments was published in 1757 and contains 3083 stars exactly.

Star maps

The Chinese drew many maps of stars in the past centuries. It is debatable as to which counts as the oldest star maps, since pottery and old artifacts can also be considered star maps. One of the oldest existent star maps in printed form is from Su Song's celestial atlas of 1092 CE, which was included in the horological treatise on his clocktower. The most famous one is perhaps the Dunhuang map found in Dunhuang, Gansu. Uncovered by the British archaeologist Marc Aurel Stein in 1907, the star map was brought to the British Museum in London. The map was drawn on paper and represents the complete sky, with more than 1,350 stars. Although ancient Babylonians and Greeks also observed the sky and catalogued stars, no such complete record of the stars may exist or survive. Hence, this is the oldest chart of the skies at present.
According to recent studies, the map may date the manuscript to as early as the seventh century CE. Scholars believe the star map dates from 705 to 710 CE, which is the reign of Emperor Zhongzong of Tang. There are some texts describing the movement of the sun along the sky each month, which was not based on the observation at that time.