天球儀

The celestial globe invented by Zhang Heng, Chinese scientist of the East Han Dynasty （25 A.D. - 220 A.D.), was the first of its kind in the world. It determined that the angular diameter of both the sun and the moon was 0.5° and the obliquity of the ecliptic was 24°. 中國東漢科學家張衡發明的天球儀是世界上最早的天球儀。 它可以測出太陽和月亮的角直徑都是0.5度，黃赤交角為24度。