Astronomical Observation Terrace

The Observatory was built in the early Yuan Dynasty. It is the oldest astronomical observatory in my country and also an astronomical science building in the world. Guo Shoujing once re-observed the positions of the twenty-eight constellations and some other stars here, and compiled the advanced calendar at that time - the Shushi calendar. The establishment of the Observatory represented the great achievements of my country's astronomical science at that time. The front and back courtyards of the Observatory are divided into seven sections: the screen wall, the mountain gate, the hanging flower gate, the Zhougong Shadow Observation Platform, the main hall, the Observatory, and the Locust Hall. More than ten kinds of astronomical instruments are replicated and installed in the courtyard. The Observatory is a mixed brick and stone structure, consisting of two parts: the platform body and the stone gui. The platform body is square and bucket-shaped, and the four walls are made of water-ground bricks. The platform is 9.46 meters high, and the small room on the top of the platform is 12.62 meters high. The top side is more than 8 meters long, and the base side is more than 16 meters long. The four walls of the platform are obviously inclined inward to the center, and its proportion of points shows the characteristics of early Chinese architecture. The small room on the top of the platform was built during the renovation in the seventh year of Jiajing in the Ming Dynasty (1528 AD). There are two symmetrical steps on the north wall below the platform, from which people can climb to the top of the platform. In order to drain the rainwater on the top of the platform and the steps, a water channel hole is set at each corner of the steps, and the water outlet is carved into a stone dragon head. In the middle of the north wall of the platform, there is a groove that goes straight up and down. The east and west walls are narrowed, and the south wall is vertical up and down, 36 cm away from the south end of the stone gui. The stone gui is used to measure the length of the sun's shadow, so it is also called "the ruler of measuring the sky". Its surface is paved with 36 square bluestone slabs in succession, and the lower part is a brick base. The stone gui is 31.196 meters long, 0.53 meters wide, 0.56 meters high at the south end, and 0.62 meters high at the north end. The stone gui is in the meridian direction. There are two water channels engraved on the surface of the gui. There is a square water filling pool at the south end of the waterway, and a long strip water discharge pool at the north end. There are water discharge holes at the east and west ends of the water discharge pool. The bottom of the pool and the channel is higher in the south and lower in the north. After filling, the water can be filled into the entire channel. When not in use, the water can be discharged. At the bottom of the water discharge pool, there is a water receiving stone base, which is a rectangular east-west orientation, and a circle of water troughs is also carved on it.