Mars From Afar
Volcano
This mosaic of images taken by Viking 1 on June 22, 1978, shows
Olympus Mons, the highest known volcano in the solar system. Its
summit caldera lies over 78,500 feet above the surrounding plains,
making it over two and a half times the height of Mt. Everest. The
volcano proper, defined by the roughly circular cone visible in the
center of the image, is about 340 miles in diameter, revealing just
how gradual a slope the mountain's flanks display. Encircling the
volcano is a moat of lava thought to have come from Olympus Mons.