回复：一次流星雨能有多少人看到？

Let r be the hight of the star. R is the radius of the earth. A is the area of the spherical cap and B is the area of the the surface of the earch. It is not difficult to get

A/B = r/(2(R+r)). Take r = 50, get A/B = 0.0038... r = 40 get A/B = 0.00310...