Re: Not necessariy . . .
And if we're following a lunar orbit, not at all.
The lunar orbit is not directly on line with the Earth's equator, otherwise we would have lunar and solar eclipses every month. You periods of darkness would be just a few hours long, but there would not necessarily be 13 of them every year. Besides, battery-powered lighting could be readily available for any extended period of darkness.
What are you trying to figure out, anyway?
Well, I'm off the net, now. Gotta get some sleep for the morning's meteor-scare, then I'll be spending the day with various honey-dos.
Cheers,
Dan