The sun dips toward the horizon only to arch away in this composite photo, taken over the course of 11 Martian days (or “sols”) by the Phoenix Mars Lander in July of 2008. Like the polar regions on Earth, the sun does not set for weeks during the summer season in the Martian far north.
The sun appears slightly smaller in the sky on Mars, since it is further from it than we are.
The stationary Phoenix Lander studied the polar region and its soil composition for evidence of water ice, and possible past habitability. It has fulfilled its mission objectives, and has ceased communications since December 21, 2008. It is unlikely that its instruments will survive the cold polar winter on Mars.
Image credit: NASA/JPL-Caltech/University of Arizona/Texas A&M University