This rare view of a Mars sunset, part of their extensive legacy of images from the martian surface, was recorded by the Spirit rover on May 19, 2005. The martian dust particles suspended in the thin atmosphere lend the sky a reddish color, but the dust also scatters blue light in the forward direction, creating a bluish sky glow near the setting Sun. The Sun is setting behind the Gusev crater rim wall some 80 kilometers (50 miles) in the distance. Because Mars is farther away, the Sun is less bright and only about two thirds the size seen from the rumored-to-be-life-bearing planet called Earth.
Image Credit: Mars Exploration Rover Mission, Texas A&M, Cornell, JPL, NASA.