Can you tell if a photograph was taken at sunrise or at sunset? It's a question I get quite often.
Through the years my answer had always been no because, in spite of witnessing and photographing my share of twilights, I could never tell unless I took the picture myself. Maybe you can if you've familiar with the place and know how it looks like at sunrise or sunset, or if there is some element in the photograph that is present only at one time and not the other. Otherwise... just enjoy it. Enjoy.
(Pixel-peepers: This shot was definitely taken at sunset because I took it myself. The setting sun would be to my right, that's why the color of the clouds face that direction.)