Nick Carver, a photographer, had a really interesting video recently where he explained the progression of light at sunset. Prior to watching the video, I understood the primary phenomenon of Rayleigh scattering, so I didn't really expect to learn anything. However, there's a lot more going on as the sun sets than I realized. The properties of sunlight (color, hardness, direction) shift in interesting and surprising ways even after the sun falls below the horizon.
The segment begins at 7:10, but if you already have a basic familiarity with the science, you can probably skip to 12:00.