Martian Sunset.

This month, the Mars Exploration Rovers are celebrating their 5th anniversary of operations on the surface of the Red Planet. The serene sunset view , part of their extensive legacy of images from the martian surface , was recorded by the Spirit rover on May 19, 2005. Colors in the image have been slightly exaggerated but would likely be apparent to a human explorer's eye . Of course, fine 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 planet Earth.