[填空题]
Eclipses happen on Earth because of an amazing coinc8b/w na7pu6zfus (6tpym0ah 2 idence. Calculate, r 8vdti0el,+rusing the information inside the Front Cover, the angulaile +80v rd,rtr diameters (in radians) of the Sun and the Moon, as seen on Earth. Sun = $rad$ Moon = $rad$