So you want to know how you can see the International Space station with your naked eye even when it’s dark on Earth?
Very easily, because up there the sun is still shining while you’re in the dark. Kind of like seeing the peak of a mountain in the sunlight while the valley has long ago become dark. The ISS does go dark too, but there’s a period when it’s dark where you are and light where it is.
Once I had a cat caught on the roof of my house. It was early evening and dark. I got a ladder and climbed up to the roof to rescue the cat when this mysterious, very bright light moved steadily, silently and perfectly straight across the sky. It was, of course, the ISS, which was at that time directly over my head. It was awesome.