央视网消息：位于河南登封的观星台遗址建筑群是我国现存最古老的天文台之一，也是元代科学家郭守敬编制《授时历》的重要遗址。这里既 体现了我国古代"天人合一"的文化思想，又彰显了古人探寻自然规律的"求真"精神。 在河南登封观星台遗址建筑群中，首先映入人们眼帘的是周公测影台。这座始建于周朝的观测日影的设备，是我国最早装置圭表的观测台。水 平为圭、垂直为表，在阳光的照射下，表的影子在圭上缓慢移动，人们由此判断时节的更替变化。这背后还流传着"周公测影定地中"的千古佳 话。相传西周初年，周公旦辅佐周成王理政时，为了确定天下的"中心"，派人遍历九州测量日影。 河南登封二十四节气非遗传承人郭杏介绍，周公在测量的时候发现，有一个日影最短的一天，影长一尺五寸，从气候上来说，从这一天了以后 就进入了最炎热的季节。从时长上来说，这一天白昼最长、黑夜最短。因为它是夏天，所以周公给它命了一个名字，叫做夏至，于是这就有了 中国二十四节气最早的第一个节气——夏至。 据《周礼》记载："日至之景，尺有五寸，谓之地中。"正是对这一观测结果的文字佐证。与夏至相对应，日影最长的那天被定为冬至，而夏至 与冬至日影长度的中点，则分别是春分和秋分。 郭杏表示 ...

Core Viewpoint - The article discusses the historical significance of the "Shou Shi Li" (授时历) and the innovations in astronomical instruments during the Yuan Dynasty, highlighting the transition from traditional observational methods to mathematical modeling in ancient Chinese astronomy [1][2]. Group 1: Historical Context - The exploration of time by humans evolved from simple observations of natural phenomena to the need for precise calendars as agricultural civilization developed [1]. - The "Si Hai Ce Yan" (四海测验) conducted by scholars like Xu Heng, Wang Xun, and Guo Shoujing involved extensive astronomical measurements across 27 locations, laying the foundation for the new calendar [1]. Group 2: Innovations in Astronomy - Guo Shoujing reformed traditional astronomical instruments, creating the "Jian Yi" (简仪) and "Yang Yi" (仰仪), which significantly improved observational accuracy and efficiency, surpassing the precision of the Song Dynasty's instruments [2]. - The "Jian Yi" became the precursor to modern equatorial instruments, symbolizing the ancient concept of "Heavenly Round and Earthly Square" through its design [2]. Group 3: The "Shou Shi Li" - The "Shou Shi Li" was developed based on precise astronomical measurements, achieving a year value of 365.2425 days, matching the Gregorian calendar and being 300 years ahead in precision [2]. - The calendar's solar terms were calculated with remarkable accuracy, differing by only 2 minutes from modern astronomical results, and it was used for over 380 years, influencing agricultural practices in China and neighboring regions [2].