Midnight Sun on Mars

Image source with more information
Credit: NASA/JPL-Caltech/University of Arizona
/Texas A&M University

Whichever planet you're on, as long as it has a tilted axis, the seasons work the same. This is essentially a time-lapse image taken by Phoenix, showing the movement of the sun in the Martian arctic as the Red Planet enters northern winter.

So: a photo of an alien sunset that doesn't happen. Rather nifty, I think.