"NASA's Curiosity Mars rover recorded this view of the sun setting at the close of the mission's 956th Martian day, or sol (April 15, 2015), from the rover's location in Gale Crater.This was the first sunset observed in color by Curiosity. The image comes from the left-eye camera of the rover's Mast Camera (Mastcam)."

If you look closely, you can see Tars Tarkas leading a tribe of Tharks into battle.

http://feeds.boingboing.net/~r/boingboing/iBag/~3/qrKV7twEEjQ/martian-sunset-photo.html