Night Lights

Night Lights
Originally uploaded by europeanspaceagency.

I'm very curious about the illuminated yellow ring here. Could that possibly be illuminated water vapor in the atmosphere, or is it more likely to be an optical effect from the window or camera, or even an artifact? It doesn't seem to be the latter, but I know little about how the various elements in this sort of photography combine. And it seems too even and too far south to have anything to do with auroras, but I could be wrong there, too.