I told you befor that I suspected I had actually caught some polar lights on my lucky train picture. About two days after it, and this one, were taken, I checked the forums again. People now had posted pictures with a similar pink glow and said it was faint polar lights. As they were taken approximately during the same time window, I am taking it as confirmation.
This picture was taken shortly before the train came back and gave me the chance to take to above mentioned foto. It’s my second lucky picture that day. Not so lucky for someone else, unfortunately, but I do appreciate the blue line.