Guo Shoujing memorial hall stargazing platform

Stargazing platform, also known as "shadow measuring platform". Located behind the bronze statue of Guo Shoujing in Dahuoquan Park, Xingtai. This is a building altimeter, which is used to measure the length of the sun shadow. 1985 completed in September. The three characters "Stargazing Platform" were inscribed by Liu, director of the Standing Committee of Hebei Provincial People's Congress. In A.D. 1279, Guo Shoujing presided over the famous Four Seas Test. During this period, he personally presided over the construction of the Dengfeng Star Observatory in Henan Province, which has been listed as a national key cultural relics protection unit. The observatory is modeled after the scale of Dengfeng Observatory 1: 1. It consists of two parts, one is a terrace building, and the other is a stone laurel paved by a groove on the north wall of the terrace. The platform building is 8.9 meters high, and the observation room at the top of the platform is 1 1.96 meters high. The length of the platform is16.85m from east to west,16.37m from north to south, 8.05m from east to west and 7.55m from north to south. Astronomical instruments, such as simple instruments and eye-up instruments, can be placed on the top of the platform to observe the sun, moon and stars. A copper bar with a length of 1.97 m and a diameter of 0.08 m is horizontally placed between two observation rooms, which is also called a beam. There is a laurel under the beam, which is 3 1.39 meters long, 0.53 meters wide and 0.4 meters off the ground. It consists of 36 bluestones. The reed surface has scales, so it is also called a measuring ruler. Stone laurel, groove and beam form a standard table, which can observe the sun shadow. At noon, when the sun rises to the upper meridian, that is, due south, the shadow of the light beam is cast on the water surface of Guiyu in a certain proportion. By continuously observing the length of the shadow of the light beam, we can calculate the length of the tropic year and the time of the twenty-four solar terms. In that year, Guo Shoujing calculated by this method that the length of a tropical year was 365.2425 days.