
The (almost) full moon was out, to the right of the frame, and the black spot is actually the shadow cast by the cliff on the waterI would clone in that black spot in the lower left corner.
I only saw my first light show a couple years ago and have been an "aurora hunter" ever since. It's addictive, really. I've uploaded a couple more images to my FB page in case you're interested.Excellent capture! I'm lucky enough to have witnessed this once in my life in the U.P. MI. I could only stare in disbelief.