中国东汉科学家张衡发明的天球仪是世界上最早的天球仪。它可以测出太阳和月亮的角直径都是0.5度，黄赤交角为24度。

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°.