Title: Olympus Mons, Mars

Source: Viking 1 Orbiter

Information: The great Martian volcano, Olympus Mons, was photographed by the Viking 1 Orbiter on July 31 from a distance of 8000 kilometers, (5000 miles). The 24 kilometer high (15 miles) mountain is seen in mid-morning, wreathed in clouds that extend up the flanks to an altitude of about 19 kilometers (12 miles). The multi-ringed caldera (volcanic crater), some 80 kilometers (50 miles) across, pushes up into the stratosphere and appears cloud-free at this time. The cloud cover is most intense on the far western side of the mountain. A well defined wave cloud train extends several hundred miles beyond the mountain (upper left). The planet's limb can be seen at upper left corner. It also shows extensive stratified hazes. The clouds are thought to be composed principally of water ice condensed from the atmosphere as it cools while moving up the slopes of the volcano. In the Martian afternoon, the clouds develop sufficiently to be seen from Earth, and it is known that they are a seasonal phenomenon largely limited to spring and summer in the northern hemisphere. Olympus Mons is about 600 kilometers (375 miles) across at the base and would extend from San Francisco to Los Angeles.