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Gaocheng Astronomical Observatory

UNESCO World Heritage Site
Interactive map of Gaocheng Astronomical Observatory
Official name	Historic Monuments of Dengfeng in "The Center of Heaven and Earth"
Includes	Taishi Que Gates,Zhongue Temple Shaoshi Que Gates Qimu Que Gates Songye Temple Pagoda Architectural Complex ofShaolin Temple Kernel Compound Chuzu Temple Pagoda Forest Huishan Temple Songyang Academy of Classical Learning Observatory
Criteria	Cultural: (iii)(vi)
Reference	1305rev
Inscription	2010 (34thSession)
Area	825 ha (2,040 acres)
Buffer zone	3,438.1 ha (8,496 acres)

Gaocheng Astronomical Observatory, also known as theDengfeng Observatory, is an observatory inDuke of Zhou's shrine, Gaocheng Town, nearDengfeng inHenan province, China. This site has a long tradition of astronomical observations, from the time of theWestern Zhou up to the earlyYuan dynasty. There is also agnomon used for the Da Yan calendar in 729 AD and the great observatory of the Yuan dynasty. As part of the "Dengfeng Historic Monuments of Dengfeng 'in the Center of Heaven and Earth'" the observatory was listed as aUNESCOWorld Heritage Site in 2010.^[1]

It is believed that theDuke of Zhou (c. 1042 BC) had erected at this place aCeyingtai (observatory measuring the shade orgnomon) to observe the Sun, as he believed the area to be the centre of heaven and earth.^[2] His interest in mathematics, astronomy/astrology is reported in theZhoubi Suanjing.

The astronomerYi Xing (683–727) of theTang dynasty built 20 standardized gnomons spread out over China to measure theequation of time dependent on the geographical location. Following a proposition of Liu Zhuo from 604 AD, 10 of these were aligned along the meridian 114° east ofGreenwich from Central Asia down to Vietnam in order to determine the circumference of the Earth and deviations from a perfect sphere. One of these 10 observatories was situated at Gaocheng. The observations were used to establish the Da Yan calendar.

South of the observatory, in the temple dedicated to Zhou Gong can be found a Shigui chart made by Yi Xing. According to theZhou Li (Rites of Zhou) this place is the center of the Earth.^[2]

The great observatory was built in 1276 in the earlyYuan dynasty on the order ofKublai Khan and was designed by astronomersGuo Shoujing (1231–c.1215) and Wang Xun (1235–1281) to observe the movement of the sun and the stars and to record time.^[2]

It was built of stones and bricks. It has two parts: the body andshigui (also calledthe ruler to measure the sky). It is 9.46 meters high by itself, and 12.62 meters high if the 2 cabinets on the top are included. The somewhat unconventional gnomon is a bar mounted horizontally between the two cabinets. The shigui extending to the far north is 31.19 meters long and 0.53 meters wide. It is made up of 36 square stones with two parallel waterways on it to check its levelness. The location of shigui is in accordance with the direction we take today to measure the meridian. During measurement, a beam is put across the grooves. Jingfu (an instrument with many holes) on the waterways is used to measure the shadow, whose precision is within 2 millimeters. At winter solstice, the length of the shadow at noon is nearly as long as the shigui.

The very precise observations served for the new Shoushi calendar (Season-Granting Calendar) of 1281, which was in use for 364 years. It was by far the most advanced calendar for its time; the length of thetropical year was determined to 365 d 5 h 49 m 20 s, a value in accord with the value of theGregorian Calendar, but obtained 300 years earlier.^[2]

In 1787,Laplace applied these measurements to check his calculations on the secular changes of the obliquity of the ecliptic and the eccentricity of the Earth's orbit.

It is the first in a series of 27 observatories built in the early Yuan dynasty.

• Taosi (Xiangfen, Shanxi), a lateLongshan neolithic site suggested to contain an ancient observatory
• List of astronomical observatories

• The Antiquarian Society
• Early Chinese Astronomy
• Ancient Observatories
• Gaocheng at ChinaCulture.org showing both observatories
• Surveying of the meridian
• "Article on the Shoushi calendar from the National University of Singapore"(PDF). Archived fromthe original(PDF) on 2011-05-17. Retrieved2007-04-13. (509 KB)

34°24′10″N113°08′27″E / 34.40278°N 113.14083°E /34.40278; 113.14083

• Astronomical observatories in China
• Buildings and structures in Zhengzhou
• Tourist attractions in Zhengzhou
• World Heritage Sites in China
• Major National Historical and Cultural Sites in Henan
• Traditional Chinese architecture
• Dengfeng

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