DW> Actually, the ISS is in darkness for less than half the time. It's a
DW> few hundred kilometres above the surface fo the earth, so it receives
DW> sunlight when the ground below it is just in darkness. Suppose it's 400
DW> km up. The earth's diameter is about 13,000 km. So the length of the
DW> tangent from the surface to the station would be sqr(400 * 13400),
DW> which is about 2300 km. That's about 1/20 of the circumference of the
DW> orbit. If my brain is working right, that means the station is in
DW> sunlight for about 60% of the time, when the sun is in the plane of
DW> the orbit. When it isn't, the fraction would be even higher.
 
I think there even is a scenario where the ISS is 100% of the day, or close
to it, in sunlight. I would say with its orbit in the right inclination
there comes a time during summer and a time during winter when al of it
might be exposed to the sun on a 24hr basis. For a while at least.
 
 \%/{at}rd 

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