Visible or Illuminated Fraction of Total Surface Area of a SphereThis program computes the visible fraction or illuminated fraction of the total surface area of a sphere at any distance from the eye or point light source as reckoned from the center or surface of the sphere.
The radius and distance can be in any convenient linear units. The default values are the mean lunar radius and the mean geocentric lunar distance in statute miles.
For a sphere of radius
or point-light source is
Visible or illuminated fraction of surface =
Invisible or shaded fraction =
© 2017 - Jay Tanner