It is the dragonfly, in particular one named the Four-Spot Skimmer. I have not yet seen a Four-Spot Skimmer here, but I did see this dragonfly last night:Richard Orr -- thanks, Richard!)
nautical or astronomical twilight. I have gotten used to sleeping with a light sky, but I still find myself staying up very late as there is no darkness "cue" to tell me to get sleepy. Good thing the Internet is always there to entertain me!