Crossing a desert in search of an oasis, high in the mountains on their way to summer pastures, moving from place to place following the herds, the ancients looked to the sun and the stars to orient themselves, find their way, foretell the seasons, and for their gods.

The evidence of these prehistoric stargazers shows man searching for guidance, not only on foot but through life. The gods lived among the stars and planets, or were the stars and planets. Once early man saw the regularity of patterns they began to see conscious entities guiding those patterns. Once they could predict the seasons and direction, they looked to the stars to predict everything.

In China, the history of astronomy begins before the written record. While there is some evidence going back to the 15th century BC, it was during the Neolithic Age that the earliest records of stars are found carved into shells and bones. Evidence of celestial observation has been found dating back to at least 14000 BC and perhaps earlier.

Astronomy truly is an ancient science in China. In fact, mankind's first record of an eclipse of the Sun was made in China in 2136 BC. By 2300 BC, ancient Chinese astrologers, already had sophisticated observatory buildings, and as early as 2650 BC, Li Shu was writing about astronomy. Observing total solar eclipses was a major element of forecasting the future health and successes of the Emperor, and astrologers were left with the onerous task of trying to anticipate when these events might occur. Failure to get the prediction right, in at least one recorded case in 2300 BC resulted in the beheading of two astrologers. Because the pattern of total solar eclipses is erratic in any specific geographic location, many astrologers no doubt lost their heads. By about 20 BC, surviving documents show that Chinese astrologers understood what caused eclipses, and by 8 BC some predictions of total solar eclipse were made using the 135-month recurrence period. By AD 206 Chinese astrologers could predict solar eclipses by analyzing the Moon's motion.

Ancient Chinese astronomy was primarily a government activity. It was the astronomer's role to keep track of the solar, lunar, and planetary motions as well as divine what astronomical phenomena may mean for the ruling emperor. Solar eclipses, infrequent and dramatic, were important enough to be recorded in chronicles and on "oracle" bones. Oracle bones are pieces of animal bones and tortoise shells inscribed with astronomical observations that were probably used for divinations. Oracle bones hail from the Shang dynasty during 1600 until 1050 BC and make many references to solar eclipses.
Eclipse observations from the Chou dynasty and Warring States period during 1050 until 221 BC and onward it appears that some astronomers recognized eclipses as naturally occurring phenomena. From the Chou dynasty, 36 solar eclipse observations are recorded in the Ch'un-ch'iu beginning around 720 BC. The Piao and the Shih-chi documents refer to nine solar eclipses from the Warring States period.

Records of solar eclipses from the Han dynasty (206 BC - 220 AD) are found primarily in two official histories: the Han-shu and the Hou-han-shu. There are no records of eclipses from the Ch-in dynasty which came just prior to the Han dynasty (221 BC - 206 BC). During the Ming dynasty from 1368 until 1644 AD, total solar eclipse observations are found in the histories of Ming provinces after 1500 AD. Prior to 1500 AD, eclipse records can be found in the Imperial Annals. These observations, however, are not of total solar eclipses. Aug 20, 1514 AD: "At the hour of wu suddenly the Sun was eclipsed; it was total. Stars were seen and it was dark. Objects could not be discerned at arm's length. The domestic animals were alarmed and people were terrified. After one (double-)hour it became light."

Earliest Chinese Calendar

The earliest calendars can be traced to the Neolithic period. Rudimentary calendar were carved into turtle bones before 2000 BC and oracle bones show that the Chinese used a year of 365 days and a lunar month of about 29 or 30 days. But it is only with the beginning of the dynastic period that calendars were standardized and formalized. From the Shang Dynasty (1523-1027 BC) to the Warring States Period (770-221 BC) there was continuous improvement in observation and thus the calendar improved, all of the calendars were based on the average motion of the moon and measured a month as starting and ending with the new moon. During the Yin period of the Shang Dynasty the calendar gradually took an embryonic form, then developed more and more. The best records start with the Spring and Autumn Period (722-481 BC) and the Warring States Period (403-221 BC) of the Zhou Dynasty. The Huangdi Li, Zhuanxu Li, Xia Li, Yin LiZhou Li, and Lu Li were some of the earliest formal calendars officially recognized by the dynasties at the time.

The Chinese calendar developed on a lunisolar basis. Observations of both the lunar cycle and the solar cycle were necessary to predict recurring events. The challenge of combining the two cycles stimulated developments in mathematics and astronomy through history. The function of the calendar was both agricultural and astrological. Divination of the future was an important part of the power of the ruler. Harnessing the magic of the calendar to do so meant that dynasties through history supported the science of astronomy in order to get more accurate astrological predictions.

It was during the Warring States Period that the 24 Seasonal Segments or èrshísì jiéqì were incorporated into the calendar. The sky is divided into 24 segments or jiéqì based on the seasons of the year. The earliest calendars assumed that the motion of the sun was constant and divided the year into 24 segments with equal numbers of days. This method is called píngqì. Because the motion of the sun is not consistent, this was found to be inaccurate. The calendar then changed to a method where the ecliptic, the path of the sun as seen from earth was divided into 24 equal parts of 15 degrees. This method is called dìngqì. Calendars from the Warring States Period through the Ming Dynasty used the pingqi method in their designs and only changed to the more accurate dingqi method during the Qing Dynasty.

Astrology and the need for symmetry drove the form of the calendar, but also drove the Daoists to develop new and better techniques to observe the stars and to keep time. They both contributed to the advance of astronomy and influenced its course through the dynasties. Daoist beliefs supported the astrological principle that the Emperor bore a Mandate from Heaven. The obsession of the throne with time and time keeping came from a desire to be in harmony with the heavens and the belief that the emperor was indeed chosen by the gods to be one with them and to rule on earth.

Confucius wrote about ritual and the need for proper observation of ritual to maintain good government, but that was a reflection of the belief system that supported elaborate ritual to affect change in or to appease the heavens. Performing the rites of Spring on the correct day at the correct hour and in the correct manner as defined by the position of the stars and the moon would determine whether your dynasty would last and your personal good fortune would continue.

Calendar creation served religious, philosophical and political purposes well beyond the need to predict the correct day to plant the wheat. Evenness and balance were imposed on the calendar and when it was no longer accurate it was reset. The external principles and concepts had more reality than did the actual days.

Chinese Constellations - The Four Quarters of the Night Sky

Constellations serve as a mnemonic to aid our memory. The organization of the stars is random to the untutored eye. By finding a relationship among groups of stars, early man made it easier to both remember them and to locate them quickly among the thousands visible in a segment of sky. Gradually, these images took on beliefs about their properties and myth was woven around the natural phenomena that were thought to control fortune. This ability to notice coincidence and attach causal properties to it underlies not only superstitious belief but also lay the foundation for predicting seasons, counting years, observing comets, and eventually reaching the moon.

Because the stars revolve around the Celestial Pole it is seen as the center of heaven and belongs to all directions, it is divided into three regions of sky surrounding Polaris (Beijíxing). The three regions are: the Purple Forbidden Enclosure (Zi Wei Yuán), the Supreme Palace Enclosure (Tài Wei Yuán) and the Heavenly Market Enclosure (Tian Shì Yuán). These regions reflect the organization of the dynastic hierarchy on earth, with the Purple Forbidden Enclosure being the most important. The concept that earthly government is organized like that of heaven gives its structure and actions legitimacy and supports the Mandate of Heaven.

The constellations or Xiù are grouped by the four directions, East, West, South and North. The dragon occupies the East, the tiger is in the West, the scarlet or vermillion bird is in the South and the tortoise occupies the North.

Chinese Advanced Theories of the Solar System

There were three major theories of cosmology over the course of Chinese history. The first view of the heavens as a great canopy or cover was by Gài Tian and originated around the 12th century BC. The second, Hún Tian, proposed by Zhang Heng, compared the cosmos to an egg with the earth at the center. The third saw all heavenly bodies floating in space, Xuan Yè. The second and third were both proposed during the Eastern Han Dynasty (25-220 AD). Chinese astronomy paid little attention to cosmology, accepting the spherical heavens model as proposed by Zhang Heng as adequate. The Polestar was seen as the center of the heavens and the fact that it was not at the zenith was explained in folk tales by charming stories to explain how the south had slipped down and the north had risen in relation to the heavens.

Ancient Chinese Discovered Halley's Comet in 240 BC

Comets (Huìxing) have been observed and recorded in China since the Shang Dynasty (1600-1046 BC). The set of comet illustrations shown above is from a silk book, Bóshu, written during the western Han period. The different shapes and characteristics of the comet tails were outlined and on some of the comets differences in the appearance of the core of the comet were noted.
From the Yin period of the Shang Dynasty to the end of the Qing Dynasty in 1911, comets were observed and recorded more than 360 times. In 635 BC, Chinese astronomers pointed out that the comet tail always pointed away from the sun.

The first verified record of Halley's Comet was made in China in 240 BC. However, in 613 BC in the Spring and Autumn Annals (Chunqiu) of Confucius, reference was made to a comet. It said: "In July, there was a comet that entered the Big Dipper." This may have been a reference to the appearance of Halley's comet that would have been in 620 BC. British astronomer, Sir Edmond Halley, did not record its appearance until centuries later in 1531 AD.

Zhang Heng Invents the Odometer

Zhang Heng was an astronomer, mathematician, engineer, and painter who lived during the Eastern Han Dynasty (25-220 AD, Dong Hàn). He is one of a long line of astronomers who served the emperors through the various dynasties. Astronomers served an important function of State by creating and maintaining calendars, making predictions concerning celestial events, and keeping records of the events observed in the heavens. The belief that the organization of civil life was a reflection of and controlled by the heavens demanded careful attention to events that might influence government.

Zhang Heng was the influenced from every source and excelled in most fields. In mathematics he estimated the mathematical value of pi as the square root of 10 or 3.1622. He also invented a cart to measure the Chinese mile. It was the first odometer.

In his treatise Líng Xiàn or Mystical Laws he proposed a theory of the universe that compared it to an egg. "The sky is like a hen's egg and is as round as a crossbow pellet. The Earth is like the yolk of the egg, lying alone at the center. The sky is large and the Earth is small." The universe originated from chaos or yuánqì. He said that the sun, moon, and planets were on the inside of the sphere and moved at different rates. He explained lunar eclipses and demonstrated the process with an armillary such as the one shown below. He demonstrated that the moon did not have independent light but that it merely reflected the light from the sun. He showed that lunar eclipses occurred relatively frequently because the moon moved faster within the sphere of the heavens.

Geng Shòucang Invents the Celestial Globe

The armillary sphere or celestial globe (tianti yí) was invented by Geng Shòucang between 70 BC and 50 BC. Zhang Heng had a bronze celestial globe constructed on the basis of a bamboo model. He improved it by remapping over 2000 stars and by powering it so that it would make one rotation per year. He employed a complicated gear system to link the armillary to a kettle clepsydra or water clock. As the water dripped from one pan to another the weight would drive the gears and the sphere would advance. He added a gear-driven device that demonstrated the waxing and waning of the moon. This was the first powered armillary.

After Zhang Heng, Ge Heng of the Wu (229 to 280) in the Three Kingdom Period and then Qian Lezhi (Liu Song Dynasty 420-478) also developed water powered celestial globe. In 721 AD the monk Yi Xing and the military engineer Liang Lingzan and others designed and made a water powered celestial globe that was an improvement on Zhang Heng's. This one not only could demonstrate apparent motion of celestial bodies, but also installed two wooden men who hit a drum to sound the time. The stars could move according to time but the planets also moved in their irregular patterns by means of a series of bronze wheels. They installed it on the grounds of the palace in the capital Chang'an.

Su Song and Han Gonglian and others made ones even bigger, ones that you looked through a pinhole to see the lights of the stars reflected on the inside. The light source was outside of the globe. Modern versions have the light source inside the globe so that they can project as in a planetarium or they glow and the surface is examined like a globe.

Zhang Heng Invents the Seismometer

The seismometer or hòufeng dìdòng yí that Zhang Heng invented in 132 AD was an urn with some type of pendulum apparatus contained within it. We don't know the exact mechanics because they were lost in history. The pendulum was extremely sensitive to vibration. When it swung it released a ball from the mouth of one of eight dragons and the ball fell into the mouth of a patiently waiting frog. The loud clang that resulted notified attendants of some sort of seismological event. It is said that one day the ball fell but people in the court felt nothing. A few days later a runner arrived from a village 400 miles away to inform the Emperor that his area had been devastated by an earthquake. While Zhang Heng's seismograph couldn't predict a quake it could notify the court when one occurred so that aid could be sent.

China has been plagued by quakes through history. The most recent major quake was the Tangshan earthquake in 1976 measuring 8.2 on the Richter scale. Tangshan is on the north China plane. The quake killed more than a quarter million people. There is frequent activity along the Gansu Corridor, the Shanxi plateau, the Xi'an (Chang'an) area, the Beijing area and the western and northern edges of the north China plain. In the east, from Shenyang in the north to Nanjing in the south there are moderately frequent quakes. The western provinces of Sichuan, Yunnan, Tibet and Xinjiang also have high levels of quake activity. In the south quakes are centered on the Fujian coast and Taiwan. For that reason, China is a major source of earthquake detection and prediction research. Historical records are of great interest to study both the risk level and to look for patterns over time. As part of that research, Feng Rui and Yu Yan-xiang concluded that the earthquake that first set off Zhang Heng's seismograph was magnitude 7 in Longxi with an epicenter at Tianshui on December 13, 134 AD.

Li Lán Invents the Steelyard Clepsydras (Water Clocks)

The steelyard clepsydra or chènglòu is a type of water clock invented in the Northern Wei Dynasty (386-584) by a Daoist monk named Li Lán. Water is siphoned from one bucket to the other and as the weight changes in the brass bucket the steelyard changes position. The beam is marked as shown below with ridges and the guide clicks into the ridges telling the time. There should be a counter-weight or plumb hanging from the right side of the steelyard, but it seems to be missing. The steelyard clepsydra was so accurate that it replaced other forms of clepsydra or lòukè and was used into the Northern Song Dynasty (960-1127).

Up to the Eastern Han Dynasty, clepsydras were marked in gradations of 100 parts to an hour. At that time, clepsydras were primarily of the leaky bucket type, where one bucket had a pinhole in it and leaked into a second that had a floating marker which would rise and the time could be told off the gradations. There were 12 hours in a day. During the reign of Emperor Aidi, a Daoist convinced the emperor to change to 120 parts to the hour. Daoists were strongly involved in astronomy through history because they were astrologers.

For Daoists, there is a correspondence between heaven and earth. The constellations have spirits that influence events on earth. Praying to the Big Dipper or Plough is believed to change the course of events on earth and in the personal lives of the people. The Daoist calendar was based on the 28 constellations. Each constellation had its own powers. It began with the Kui constellation and at midpoint the Jiao constellation.

The Emperor was seen as the Son of Heaven with a mandate from the power of heaven to rule. Most constellations were related to the hierarchy on earth which was seen as a reflection of that in the heavens. By the end of the Han Dynasty court astronomers had grouped 1464 stars into 283 constellations. Detail was important for advising the Emperor and predicting events. Astrology led to meticulous astronomy.

In China, the stars were closely tied to the events within the dynasties, so the heavens weren’t remote from everyday life, the sky was a mirror of the Earth. Every time that something unexpected occurred in the sky, it showed a disruption on the Earth which, in effect, meant somewhere in China. To pinpoint exactly where, the Chinese split the stars into 283 small constellations, representing different parts of the Empire.

For instance, ancient Chinese astronomers spotted a brilliant new star and reported: “A guest star appeared within the Southern Gate. It was as large as half a mat; it showed the five colours and it scintillated.” The Astronomer Royal alerted the Emperor, and decisive action was taken against the region corresponding to the Southern Gate. “The governor of the metropolitan region Yuan Shao punished and eliminated the middle officials and several thousand people were killed.”

The Chinese astronomers kept watch from a raised platform, where four observers faced north, south, east and west; while a fifth lay on his back and looked straight upwards, surely the best job. The next morning they reported to the Astronomical Bureau, which kept records from 206 BC to AD 1912, the longest-lived bureaucracy the world has ever seen. Today's world astronomers can mine this ancient Chinese archive for unique information on astronomical events.