Astronomy

Most of the ancient Chinese were farmers, and hence paid special attention to astronomy, which could help them to predict the arrival of different seasons. As a result, many astronomic instruments were invented and records of observation of stars and astronomic events were made.

 Astronomical Observations and Records
 Astronomical Inventions



Astronomical Observations and Records
According to some myths, in around 1000 B.C., the first Zhou Emperor had ordered his people to build an observatory, called Ling-Tai(ÆF¥x). The Zhou astronomers observed and made records of different orbits here. They had noticed and been worried about the sun spots, which were thought to be symbols of the fate of the country. The results of the astrologers' observation and studies would be basis of the holy almanac. The Chinese's making of almanac might have begun at a very early time. It prescribed not only the lengths of different months, but also lengths of the four seasons and the date of the summer and winter solstices and spring and autumnal equinoxes, so that the length of day and night time in the equinoxes are equal, but have the greatest difference in the solstices.

The Chinese treated the changes happening in the sky as very important events. They made descriptive and detailed records of what they saw and these astronomic records became irreplaceable even in modern time.

The records of sun-spots made by the ancient Chinese has been used for modern researches. The Chinese's records of comets were also more detailed and complete than those of other old civilizations. The well known Halley's comet was first observed and recorded in 240 B.C. in China. The details of Halley's comet in this record become the basis of the calculation of its orbit nowadays. The Chinese had also recorded the occurrence of sun and moon eclipses early in the Shang Dynasty on oracle bones. This was 700 years earlier than the west-Asian Babylonians. Similar kind of records were made in later periods. After the third century, these records were more exhaustive. The astronomists at that time began to calculate the frequencies of sun eclipses and moon eclipses. However, although the Chinese scientists' calculation had been improving, they sometimes still made mistakes in their calculations. The Chinese also made star charts in early periods. The earliest star chart was written in the Period of the Warring States by Shih-shen (¥Û¥Ó) and Kan-te (¥Ì¼w) this star chart, together with a star chart which was said in myths to be written in the Shang Dynasty by Hsien (§Å«w) were included in star studies in later dynasties. Their surveys of stars were rewritten in the Period of the Six Dynasties by Chien Le-chih (¿ú¼Ö¤§) his sky chart, using the colours white, black and red.

Among the numerous stars, the stars which were paid most attention were the supernovae. The Chinese's records of these, which were the earliest in human history, had amazed modern Western astronomists. The data and information in it were the earliest and help with researches of supernovae in modern times.



Astronomical Inventions

Apart from making astronomic records, the Chinese also invented astronomic instruments, among which the armillary spheres were the most important.

This instrument was first invented in early Han Dynasty by Keng Shou-ch'ang (¯Õ¹Ø©÷).
It basically consisted of a metallic sphere and various hoops, used to separate and measure the sky. This instrument was further developed in the Eastern Han Dynasty, by the famous scientist, Chang- heng (±i¿Å) in 124 A.D.

The instrument's diameter was about one yard long. It consisted of layers of rings and hoops, representing various orbits in the universe. Chang had also made four ring gauges, representing the Equator, Prime Meridian, the Horizon and the path of the Sun seen from the Earth, called "the Yellow Orbit". These four orbits, especially the "Yellow Orbit", had helped much in predicting the coming of sun and moon eclipses and also the orbits of different stars. This advanced armillary sphere also helped in the discovery of the twenty minutes' time difference between each year. Chang also invented the water clock. It is a water-powered clock which looked like a smaller armillary sphere. The hoops and rings, with the energy of the tapping water, would rotate regularly. People could hence observe the movement of stars from this instrument.

The invention of astronomical instruments had leapt forward greatly in the Tang Dynasty. In 721, a group of well-educated monks worked with the engineer Liang Ling-tsan (±ç¥OÅÐ) in the palace in Ch'ang-an (ªø¦w). They made an astronomical clock, called the orrery. It was the first machine in the world to use time escarpment, and hence can be said to be the ancestor of clocks and watches. This instrument made use of water power to push the hoops, and hence showed the movement of stars in sky. There were also two wooden dolls at the bottom of the instrument to strike the clock regularly.
 

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