Zhougong geodesic platform

Zhougong geodesic platform

Zhougong scenery observation platform is a part of historical sites in Dengfeng, and the oldest Taoist architectural site in China.

Located 13 kilometers southeast of Dengfeng City, Gaocheng Town, the southern side of the observatory.

According to the records of Zhou Li, in the Western Zhou Dynasty, the fourth son of King Wen of Zhou, Duke Jidan of Zhou, was building the eastern capital of Luoyang, where he set up a wooden watch to measure the sun's shadow and set the 24 solar terms. In 723, when the famous astronomer and his party made astronomical observation, they ordered Nangong to replace Zhou Gong's Tu GUI wooden watch with Shi GUI stone watch, which has a history of more than 1200 years.

The height of Zhougong shadow platform is 3.91 meters, which is composed of stone GUI and stone table. Commonly known as "shadowless platform", also known as "eight foot watch", it is an instrument used in ancient China to measure the shadow of the sun, verify the time and year. It is made of bluestone, with the stone column as the table and the pedestal as the GUI.

The top of the table is a building type roof, and the character "Duke Zhou's scenery measuring platform" is engraved in the south.

Historical evolution

The earliest astronomical observation instrument in China was dedicated to the observation of the sun's shadow by tugui, and the earliest observatory to install the GUI meter was the Duke of Zhou's scenery (shadow) Observatory, which was established in Yangcheng in the early Western Zhou Dynasty. It was named because the Duke of Zhou built the Observatory to observe the sun's shadow when he built the site of Luoyi. The site is located in Gaocheng Town, Dengfeng City.

Duke Zhou was not only a famous statesman and strategist in the early Western Zhou Dynasty, but also made great achievements in astronomy and geography. He believed that in the sky, Polaris is the king of all stars, known as the "star of the emperor", located in the middle of the sky. Then the observatory must be built in the middle of the earth. After determination, he thought that Yangcheng (today's southeast Gaocheng town of Dengfeng) was "in the middle of the world". So he set up his watch here to measure the shadow of the sun. Its system is consistent with the theory of measuring the shadow of the sun by tugui recorded in Zhouli.

The watch (upright column) is eight feet (267 cm) high, and the GUI is the seat connected with the watch. The shadow of the sun's irradiator falls on GUI. On the summer solstice, the shadow at noon is the shortest, only one foot five inches (50 cm). On the winter solstice, the shadow is the longest. Using tugui to observe the shadow of the sun, we can accurately determine the two to two minutes (winter solstice, summer solstice, spring equinox and autumn equinox) and determine the length of the solar year, which provides a reliable basis for the establishment of the calendar. At the beginning of the Zhou Dynasty, the Duke of Zhou also determined "the boundary of the feudal land" according to the length of the sun shadow at the summer solstice.

Zhougong platform was used by later generations. Stone watch was built in the Tang Dynasty. According to the records of the old book of Tang Dynasty, in 723, Emperor Xuanzong of Tang Dynasty ordered Nangong, the eunuch, to imitate the old system of Duke Zhou's tugui and replace it with stone watch and stone watch.

The words "Duke Zhou's observation platform" engraved by Nangong, the astronomical official at that time, were left.

In the Yuan Dynasty, Guo Shoujing built a permanent observatory 20 meters north of the observatory, improved the original GUI and watch, and added a "peeping table" to measure the position of the moon. At that time, astronomer Guo Shoujing established observatories and observation stations in 27 places in China, and this is one of them. According to the observation and research, Guo Shoujing et al. Compiled a new calendar, the time serving calendar. It uses 365.2425 days for the return of the sun, which is the same as the current Gregorian calendar, but more than 300 years earlier. During the Ming and Qing Dynasties, the observatory was rebuilt. During the Anti Japanese War, it was destroyed by Japanese artillery.

The extant remains of the site include Zhaobi, mengmen, Jimen, Zhougong temple, Yaodian and some Ming and Qing inscriptions. Zhougong Observatory is more than 800 years earlier than Alexander Observatory and Rhodes Observatory, which were built in the second century BC. In 1961, the State Council announced the observatory as a national key cultural relic protection unit. Now there is a Chinese Astronomical Museum open to tourists.

Principle used

In fact, the study of astronomy with GUI and Biao dates back a long time. After human beings entered the animal husbandry and agricultural society, they found that both sowing and harvesting had strong seasonality. There was a difference of a few days between the morning and the evening, and the harvest was very different. People want to harvest more and better food. When to plant what crops and when to harvest. All these problems have been raised urgently. In the long-term production struggle and life experience, people have noticed that the length of the sun shadow is related to the changes of cold and summer. In order to accurately measure the seasonal changes of cold and summer, the method of instant effect has been produced.

In ancient China, the instrument used to measure the sun's shadow is called guibiao. Guibiao is a pole standing on Guiyi. Guiyi is a mound of earth on the ground. Using guibiao to measure the sun's shadow is also called pole measuring. It is a leap in the development of astronomy to study the calendar with pole measuring.

In the Zhou Dynasty, there was a standard for the use of guibiao. The pole (watch) was set at eight feet long. The Zhouli recorded that "when the sun comes, the ruler has five inches", which means that at noon on the day of the summer solstice in Gaocheng village, Dengfeng City, Henan Province, the shadow length of the eight foot watch is exactly one foot five inches.

Architectural features

The stone table is engraved with the five characters of "Duke Zhou's shadow measuring platform". The stone table is 3.95 meters high, divided into upper and lower parts. The lower part is a square stone seat with a small upper part and a large lower part. It is a willow shaped cone, called "Gui". It is about 1.965 meters high, and the upper part is a rectangular stone column, called "Biao". It is about 1.956 meters high, which is eight feet of Kaiyuan chizi in Tang Dynasty. The north side of the stone table is about 37 cm from the north side of the stone seat, about 1.5 feet in Kaiyuan of Tang Dynasty. On the day of the summer solstice, the shadow is one foot and five inches long. Therefore, the latitude of the place where the shadow was measured at that time is 34.3 degrees. On this day, the shadow length coincides with the length of the North upper edge of the stone block. There is no shadow around the lower part of the pedestal, as if it had been a day. Therefore, it is commonly known as "no shadow stage". On the back of the stone pedestal, there is a couplet inscribed by later generations: "Tao connects heaven and earth, and the stone is hidden in Yin and Yang without shadow".

The observatory is made of brick and wood. It is made up of a bucket shaped platform and a long stone wall. The height of the platform is 9.46 meters, with obvious upper and lower scores, reflecting the architectural characteristics of the song and Yuan Dynasties. In history, the observatory was destroyed by nature and man-made, and was repaired several times after Yuan Dynasty. It has become a place for academic circles and tourists at home and abroad to visit.

Reasons for setting address

"Gaocheng" means "Guyang city". "Shuo song" pointed out in the book: "Gaocheng Guyang city governance also." Mencius also talks about Yu's avoiding Shun's son in Yangcheng. After Wu Zetian held the ceremony of Dengfeng in Songshan, she arrived in Yangcheng. To celebrate the completion of the ceremony, she changed Yangcheng into Chengcheng. Cui Zhenhua and Xu Dengli pointed out in their book Chinese astronomical monuments that the reason why Zhou wanted to go to Yangcheng to measure the sun's shadow was that the capital of the Western Zhou Dynasty, hojing, was located in a remote place with inconvenient transportation, while Yangcheng was located in the Central Plains with rich products and developed culture, so the Duke of Zhou wanted to move his capital to the Central Plains. When astrology was in vogue, the rulers of Zhou Dynasty made the opinion that Yangcheng was located in the "Central Plains" and that it was the center of Jiuzhou.

"Zhou Li" has such a record: "when the sun comes, the scene is five inches long, which means that in the earth, the heaven and the earth meet, the four seasons meet, the wind and rain meet, and the Yang and Yin meet. However, Fuan is the building of a kingdom." As we all know, at the same latitude as Yangcheng, on the day of the summer solstice, the shadow of the eight foot watch is one foot five inches, which is called "Dizhong". In fact, it refers to the North-South central line of the territory at that time.

According to the county annals, Zhougong scenic platform was built when Zhougong built Luoyang, the eastern capital of Luoyang. Its function is to "measure the depth of the earth, set the sun, seek the middle of the earth, and test the four seasons". That is to say, the sun shadow is measured by setting up a tugui to measure the middle of the earth and test the seasonal variation of four o'clock. The principles and methods of measurement are as follows: first, a vertical angle (i.e. 90 degrees) must be formed between the GUI and the meter; second, the setting of GUI meter must be consistent with the local meridian (i.e. lower South due north direction); third, to observe the sun shadow, we must measure the shadow in the middle of every day, day after day, every day, and record the measured shadow length data one by one. According to the change of the sun shadow in the middle of every day, we can find out the seasonal change It's not easy. Duke Zhou defined the day with the longest shadow as "winter solstice". At noon, the sun is directly on the Tropic of cancer, and the day in the northern hemisphere is the shortest; the day with the shortest surface shadow is defined as the "summer solstice": in this day, the sun is directly on the Tropic of cancer, and the day in the northern hemisphere is the longest. The period from the day with the longest shadow in one year to the day with the longest shadow in the next year, that is, one cycle of the earth around the sun, is defined as a "regression year". In a year, two days with the same day and night, such as the appearance of the sun and shadow, are set as "spring equinox" and "autumn equinox", and then the 24 solar terms are gradually summed up to serve the production and life of human beings.

Address: in front of Zhougong temple, Gaocheng Town, 15km southeast of Dengfeng, Zhengzhou

Longitude: 113.150326

Latitude: 34.400641

Chinese PinYin : Zhou Gong Ce Jing Tai