Observation of Solar and Lunar Eclipses

     All dynasties in ancient China carried a fine tradition of recording in detail the results of astronomical observations. From the Han to the Yuan dynasties 596 solar eclipses were recorded. Ancient Chinese recorded 2,000 lunar eclipses, including 400 total eclipses. Outside China the earliest records of solar eclipses were found in the ruins of ancient Babylon, and the earliest solar eclipse among the six records took place in 911 BC. Yet in China the earliest record of solar eclipse, found in the inscriptions on bones and tortoise shells unearthed at the Yin ruins, was in 1200 BC, nearly 300 years earlier than the ancient Babylon record and more than 600 years earlier than the first record of solar eclipse in Europe. The Spring and Autumn Annals compiled by Confucius recorded 37 solar eclipses in 244 years, and 32 of them have been proved reliable.

Ancient Chinese observers made detailed records of the eclipses, including the first contact, the maximum phase, and the last contact. Ancient Chinese astronomers were so clever as to work out the cycle of repeated solar eclipses to be 777 nodical months (solar months), or 716 lunation (lunar months). This doubles the cycle of 388.5 months computed by American astronomer Simon Newcomb (1835-1909), but Newcomb calculated the cycle more than 1,000 years later. As their forecasts were so accurate, ancient Chinese astronomers were able to tell people to prepare a basin of water on the date a solar eclipse was due to occur so that they could observe the whole eclipse process, with the image of the sun reflected in the water. By studying ancient Chinese records of eclipses and other astronomical phenomena, Western scientists have established a new branch of astronomy ¨C historical astronomy.

    Astronomers in ancient China also made close observations and detailed records of lunar eclipses. China's earliest record of lunar eclipse is found in The Book of Songs, the first collection of ancient Chinese poetry. A verse in the book says, "The moon was eclipsed, and it is a normal celestial phenomenon." Studies found that this lunar eclipse occurred in the eighth month of 776 BC. It is also the earliest record of lunar eclipse in the world, 55 years earlier than the record in ancient Egypt of a lunar eclipse that occurred in the second month of 721 BC. Astronomers in ancient China also explored the cause of lunar eclipses. The Book of Changes says a lunar eclipse usually comes after increscence, or around the fifteenth day of the lunar month. Zhang Heng (78-139), a great scientist of the Eastern Han Dynasty, gave a much clearer explanation for lunar eclipses. He said that since the moon was illuminated by the sun, a lunar eclipse took place when the earth blocked the sunlight.