Mars: Regional View of the Tharsis Volcanoes | PIA02049 | ||
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The volcanoes of the Tharsis region are highlighted by this color image mosaic obtained on a single martian afternoon by the Mars Orbiter Camera (MOC) onboard the Mars Global Surveyor (MGS) spacecraft. | ||
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Image Credit: NASA/JPL/Malin Space Science Systems | |||
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The
volcanoes of the Tharsis region are highlighted by this colour image mosaic
obtained on a single martian afternoon by the Mars Orbiter Camera (MOC)
onboard the Mars Global Surveyor (MGS) spacecraft. Olympus Mons dominates
the upper left corner--it is one of the largest known volcanoes and is nearly
550 km wide. The white or bluish-white features are clouds. Clouds are common over the larger Tharsis volcanoes in mid-afternoon. The four largest volcanoes are more than 15 km high. Viewed from Earth by telescope before any spacecraft had visited the planet, astronomers often described a 'W-shaped white cloud over the Tharsis region. This 'W' was actually the result of seeing the combined effects of bright clouds hanging over the Ascraeus, Pavonis, Arsia, and Olympus volcanoes. The clouds result when warm air containg water vapor rises up the slopes of each volcano, cools at the higher altitude, and causes the water vapor to freeze and form a cloud of ice crystals. |
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Pavonis
Mons lies on the martian equator, north is up, and sunlight is illuminating
the scene from the left. The picture is a mosaic of red and blue filter
images taken on three consecutive orbits. The slightly blurred appearance
of the left side of Arsia Mons results from distortion toward the edges
of the images used to make the mosaic. To remove the blurr, an image obtained
on another day would be added to the mosaic--however, this image would not
match well because the cloud patterns will have changed by the next day.
Mosaics such as the one shown here are used to monitor changes in martian
weather and to plan future observations. |
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