Hello Ward,

On Thursday March 20 2008 09:19, you wrote to DAVID WILLIAMS:

 DW>> Another thing... Think of the solar panels on the space station.
 DW>> For good efficiency, they always have to aim at the sun. But if
 DW>> the station were rotating, the panels would have to be on fancy
 DW>> pivots so as to turn to keep facing the sun. They aren't, so they
 DW>> don't, so it isn't.

 WD> It depends how one looks upon it. There's as much logic in it to claim
 WD> that the ISS rotates all the time.

Contrary to linear translation, rotation is not relative. There is a
preferrerd frame of reference that does not rotate.

So no, it does not depend on how one looks at it and there is not as much
logic in the claim that it rotates all the time instead of it not rotating.

 WD> And I also think there are plenty of moments when the Sun is shielded
 WD> from the ISS by Earth.

Of course. You can observe that yourself when it flies over shortly after
sundown or before sunrise. If it goes from the west to east after sundown
or from east to west before sunrise, you see it as a bright light that
quite suddenly "turns off" when it enters the earth's shadow.

Have seen that happen many times.

If it flies in the other direction, one should be able to see it "turn
on" when coming out of the shadow cone, but you need to look in the
right direction at the right moment. I have not seen that yet. Seen from
the station it would be "sunrise".

Cheers, Michiel

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