Celestial Globe
The celestial globe is a device that was used in ancient China to observe the motion of celestial bodies. It is composed of two main observing devices: the armillary sphere and the celestial sphere. The armillary sphere measures the spherical coordinates of celestial bodies, while the celestial sphere demonstrates celestial phenomena. Its theoretical basis is the huntianshuo, a geocentric theory in ancient Chinese astronomy, that views the universe as a sphere, like an egg, with the Earth as the central yolk. That was a useful perspective back then.
Zhang Heng (78-139), an astronomer of the Eastern Han Dynasty (25 - 220) made significant improvements to the celestial globe based on the work of his predecessors. He created a copper celestial globe in 117. According to records, the main body of the celestial globe was a copper sphere surrounded by several layers of circles that could all rotate. The vertical circle passing through the North and South poles was called the celestial meridian, and another circle representing the horizon was called the horizon circle. On the surface of each layer were carved the South pole, the North pole, the equator, the ecliptic, the Twenty-Four Solar Terms, the twenty-eight mansions in astrology, the sun, the moon, and other celestial bodies. This ingenious design allowed the speed of the copper sphere's rotation to match that of the Earth's rotation, simulating the movement of the stars in real time.
The celestial globe is a remarkable product of ancient Chinese astronomy that had a profound impact on the world's astronomical theory and practice. Before the invention of telescopes in the 17th century, it was an essential instrument for astronomers to determine the position of celestial bodies.
浑天仪
浑天仪是中国古代观测天体运行的仪器，主要由浑仪和浑象构成。浑仪是测量天体球面坐标的一种仪器，浑象是古代用来演示天象的仪表。其理论基础是“浑天说”。该学说认为天是一个圆球，像鸡蛋，地球就像鸡蛋黄一样，立于其中，这是当时天文学说中先进的认识。
东汉天文学家张衡（78—139）在前人的基础上对浑天仪进行了重要改进，在117年制成一件铜铸浑天仪。据记 载，其主体是一个由几层均可运转的圆圈组成的铜球，其中通过南北极的圆环叫子午圈，另一个是表示地平线的地平圈。各层分别刻着南、北极，黄、赤道，二十四节气， 二十八列宿，日、月等天象。通过精妙的设计，铜球转动一周的速度和地球自转一周的速度相同，使得铜铸浑天仪能够实时模拟星空的运行。
浑天仪是中国古代天文学成就的杰出代表，对世界天文学理论及实践产生了深远的影响。在17世纪望远镜发明之前，浑天仪是天文学家在测定天体方位时必不可少的仪器。
