“That’s my colourized version of the already-classic “Midnight Sun” image created by the Phoenix team, showing the path of the Sun across the sky as seen by the Phoenix lander. Up near the martian north pole Phoenix is in the martian Land of The Midnight Sun, and the Sun never sets, it just dips down towards and then rolls over the southern horizon at midnight before climbing up again…”
Taken from phoenixpics.wordpress.com, a nice Phoenix fan site featuring the best images of the Phoenix mission thus far.