What is the angular diameter of the earth viewed from the moon? What about the earth viewed from the sun?
Let P be the point of contact of the tangent from an observer O on Moon's surface to the Earth centered at E and
Really, this is angular chord. The length of the contact chord is little short of Earth's diameter. So, the angular diameter is a little more than
From the Sun instead, #EO = 149597871-696342 = 148901529 and
sin (alpha/2) = (EP)/(EO) = 6378/148901529 = 0.0000428