Thursday, October 18, 2007

Astronomy in China has a very long history. Oracle bones from the Shang Dynasty (2nd millennium BC) record eclipses and novae. Detailed records of astronomical observations were kept from about the 6th century BC until the introduction of Western astronomy and the telescope in the 16th century. The practice of astronomy in China was fundamentally changed by extended contact with Western astronomy. Today, China continues to be active in astronomy, with many observatories and its own space program.

Early history
One of the main functions was for the purpose of timekeeping. The Chinese used a lunisolar calendar , but because the cycles of the Sun and the Moon are different, intercalation had to be done.
The Chinese calendar was considered to be symbol of a dynasty. As dynasties would rise and fall, astronomers and astrologers of each period would often prepare a new calendar to be made, with observations for that purpose.
Astrological divination was also an important part of astronomy. Astronomers took careful note of "guest stars" which suddenly appeared among the fixed stars. The supernova that created the Crab Nebula in 1054 is an example of a guest star observed by Chinese astronomers, recorded also by the Arabs, although it was not recorded by their European contemporaries. Ancient astronomical records of phenomena like supernovae and comets are sometimes used in modern astronomical studies.

Purpose of astronomical observations in the past

Chinese constellations
The divisions of the sky began with the Northern Dipper and the 28 mansions.
In early 1980s, a tomb was found at Xi Shui Po (西水坡) in Pu Yang, Henan Province. There were some clamshells and bones forming the images of the Azure Dragon, the White Tiger and the Northern Dipper. It is believed that the tomb belongs to the Neolithic Age, about 6,000 years ago.
Star names relating to the 28 lunar mansions were found on oracle bones dating back to the Wuding Period, about 3,200 years ago.
In 1978, a lacquer box was excavated from the tomb of Zeng Hou Yin in Suixian, Hubei Province. Names of the 28 lunar missions were found on the cover of the box, proofing that the use of this classification system was made before 433 BC.
As lunar mansions have such an ancient origin, the meaning of most of their names have become obscure. Even worse, name of each lunar mansion consists of only one Chinese word, and the meaning of which could vary at different times in history. So the meaning of the names are sill under discussion.
Besides 28 lunar mansions, most constellations are based on the works of Shi Shen-fu and Gan De, who were astrologists during the period of Warring States (481 BC - 221 BC) in China.
In the late period of the Ming Dynasty, the agricultural scientist and mathematician Xu Guangqi (1562 - 1633 AD) introduced 23 additional constellations which are near to the Celestial South Pole, which are based on star catalogues from the West (see Matteo Ricci).

History of Chinese constellations
Unlike the West, where the starry sky is a pantheon of Greek legendary hero and mystic creatures, the Chinese treat the heavens as a miniature of their earthly world, a reflection of their feudal society.

Chinese astronomy Classification

Star catalogues and Maps
In the 4th century BC the two Chinese astronomers responsible for the earliest information going into the star catalogues are Shi Shen, Gan De of the Warring States period. The Chinese classic text "Star Manual of Master Wu Xian" (巫咸星經), and its authorship is still in dispute because it mentioned names of Twelve Countries, which did not exist in the Shang Dynasty, the era of 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 (78 - 139 AD) not only catalogued some 2500 different stars, but also recognized over 100 different constellations. Zhang Heng also published his work Ling Xian, a summary of different astronomical theories in China at the time. In subsequent period of the Three Kingdoms (220 - 280 AD), Chen Zhuo (陳卓) 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 (1279 - 1368 AD) created a new catalogue which was believed to contain thousands of stars. Unfortunately, many of documents at that period were destroyed, including that of Shoujin. Imperial Astronomical Instruments (儀象考成) published in 1757 containing 3083 stars exactly.
The Greek Hipparchus later created the first star catalogue for the Western world during the 2nd century BC.

Star catalogues

Main article: Chinese star maps Star maps
The ancient Chinese astronomer Shi Shen (fl. 4th century BC) was aware of the relation of the moon in a solar eclipse, as he provided instructions in his writing to predict them by using the relative positions of the moon and sun.

Lunar and solar eclipses

Equipment and innovation
The earliest development of the armillary sphere in China goes back to the astronomers Shi Shen and Gan De in the 4th century BC, as they were equipped with a primitive single-ring armillary instrument. It is of great importance to note that the world's first hydraulic (i.e. water-powered) armillary sphere was created by Zhang Heng, who operated his by use of an inflow clepsydra clock (see Zhang's article for more detail).

Armillary sphere (渾儀)
Designed by famous astronomers Guo Shoujing in 1276 AD, it solved most problems found in armillary spheres at that time.
The primary structure of Abridged Armilla contains two large rings that are perpendicular to each other, of which one is parallel with the equatorial plane and is accordingly called "equatorial ring", and the other is a double-ring which is perpendicular to the center of the equatorial ring, revolves around a metallic shaft, and is called "right ascension double-ring".
The double-ring holds within itself a sighting tube with crosshairs. When observing, astronomers aim the star with the sighting tube, stars' position can be read out at the dials of the equatorial ring and the right ascension double-ring.
A foreign missionary melted the instrument in 1715 AD. The survived one was built in 1437 AD, and was taken by Germany and stored in France Embassy in 1900 during Eight-Nation Alliance. Under the pressure of international public voice the German returned it to China. In 1933 it was placed in Purple Mountain Observatory for preventing it being destroy in war. In the 1980s it had already been eroded seriously and was nearly destroy. To deal with it Nanjing government spent 11 months to repair it.

Abridged armilla (簡儀)
Besides star maps, the Chinese also made Celestial globes, which show stars position liked a star map and can present the actual sky in a specific time. Because of its Chinese name, the Chinese always make it up with Armillary sphere, which is just one word different (渾象 vs. 渾儀).
According to records, the first Celestial globe was made by Geng Shou-chang (耿壽昌) between 70BC and 50BC. In Ming Dynasty, celestial globe at that time was a huge globe, showing with the 28 mansions, celestial equator and ecliptic. But just like many other equipment, none of them survived.

Celestial globe (渾象) before Qing Dynasty
Celestial globe was named 天體儀 in Qing Dynasty. The one in Beijing Ancient Observatory was made by Belgian missionary Ferdinand Verbiest (南懷仁) 1673 AD. Unlike other Chinese celestial globes, it employs 360 degrees rather than the 365.24 degrees (which is a standard in ancient China). It is also the Chinese-first globe which shows constellations near to the Celestial South Pole.

Celestial globe (天體儀) in Qing Dynasty
The first to invent the hydraulic-powered armillary sphere was Zhang Heng (78-139 AD) of the Han Dynasty. Zhang was well-known for his brilliant applications of mechanical gears, as this was one of his most impressive inventions (alongside his seismograph to detect the cardinal direction of earthquakes that struck hundreds of miles away).
Started by Su Song (蘇頌) and his colleagues in 1086 AD and finished in 1092 AD, his large astronomical clock tower featured an armillary sphere (渾儀), a celestial globe (渾象) and a mechanical chronograph. It was operated by an escapement mechanism and the earliest known chain drive. However 35 years later the invading Jurchen army dismantled the tower in 1127 AD upon taking the capital of Kaifeng. The armillary sphere part was brought to Beijing, yet the tower was never successfully reinstated, not even by Su Song's son.
Fortunately two versions of Su Song's treatise written on his clock tower have survived the ages, so that studying his astronomical clock tower is made possible through medieval texts.

True north and planetary motion

Gan De
Guo Shoujing
Shen Kuo
Shi Shen
Su Song
Xu Guangqi
Zhang Heng Famous Chinese astronomers

Beijing Ancient Observatory
Astro Observatory Observatory
The introduction of Western science to China by Jesuit priest astronomers was a mixed blessing during the late 16th century and early 17th century.
Telescope was introduced to China in the early 17th century. The telescope was first mentioned in Chinese writing by Emanuel Diaz (Yang Ma-Nuo), who wrote his Tian Wen Lüe in 1615.

Jesuit activity in China

Book of Silk
Chinese astrology
Chinese constellation
History of astronomy
Timeline of Chinese astronomy Notes

Needham, Joseph (1986). Science and Civilization in China: Volume 3. Taipei: Caves Books, Ltd.

No comments: