I just came across the site http://bluehoursite.com/ . It is a really cool site and tells about the blue hour. It even gives the time in your given location.You can get really neat pictures of a dark blue sky after sunset and before sunrise.
Last night as I was having a bath I noticed the blue hour was approaching since there is a window with a nice view of the lob lolly pines from our second floor bathroom. I decided to put my camera on the night setting and try a few photos. The first is facing toward the West where the sun sets and it had not gotten quite to the full blue light stage.
The second is facing more towards the East. This captured more of the blue light but I did get a bit of a halo thing or double on the moon.
I will have to have more fun with this at some point. But if you go to their link you will find all kinds of interesting stuff about it.