Comment 4 for bug 1131847

Hi again!
I used Adobe Illustrator to study the geometry involved in the shadow casting of Saturn: this is my analysis for Celestia rendering.

Clearly the shadow ellipse (drawn in red) is tangent to Saturn circonference (not drawn, but easily recognizable): the effect is a shadow that casts itself onto the rings.

I admit that there are errors in the drawing itself, but this picture gives a clear idea of the situation involved in objects casting shadows.

BTW: I am a programmer since many many years and I know problems and difficulties related to shadow rendering in OpenGL! I'm quite expert in Astronomical matters like Eclipse and Celestial Mechanics...
And, why not, If I had time, I'd like to collaborate with you all, in this project I followed since the first versions!!

Thanks for your attention