Comment by PaulDavisThe1st

My impression was that you can only see them as they reflect sunlight in your direction. As the angle formed between you, the satellite and the sun changes, you will first not see the satellite, then see, then not see it again.

And of course, if it is 3am, and there is no sunlight at any altitude because the sun is on the other side of the world, no satellites are visible.

I could be wrong.