solar insolation formula needed

Kurt Jonckheere (
Mon, 30 Sep 1996 23:24:25 +0100


as you all know a satellite orbiting the earth in regularly obscured
from the sun when it is in the shadow of the earth.

Now, I would like to see the variations of the mean shadowing as a function
of time.

This mean time in the shadow of the earth will probably be a function of 
time of the year (indicating the angle between orbital plane of the sat 
and the plane of the sun), inclination, mean height and maybe some other elements.

Is there somebody who knows a *simplified* formula to calculate the mean
time in shadow given the date and the orbital elements for that epoch?

The output of the formula only has be correct within a percent or so.


Kurt Jonckheere (