Computing the Apparent Angular Diameter of the Moon As Viewed From Any Given Distance Measured From the Lunar Surface
When a planet is viewed from a very great distance, we can generally treat its angular diameter as the diameter of a flat circular disc of the same diameter without significant error. However, this approximation only works for great distances, like a million miles or kilometers or more.
When viewing a sphere from much closer, such as the moon from 150000 miles, then the actual curvarure of the spherical surface significantly effects the apparent size and a circular approximation is insufficient. The following general formulas all take into account the spherical curvature of the lunar surface based on the mean value of the lunar radius as given above.
Assuming the mean lunar radius (
The radius and distance can be expressed in any units as long as both use the same units.
The distance (
For example, if we were
© Jay Tanner - 2017