Satisfactory Essays
Mars is the fourth planet from the sun at about 228 million-km (141 million miles) and the last terrestrial planet from the sun. The next five planets in order from the sun are gaseous. Mars follows closely behind Earth but is comparatively smaller, with about half the diameter of Earth and about one-tenth of Earth’s mass. Thus the force of gravity on Mars is about one-third of that on Earth. Though it is much smaller, Mars does have the same surface land area as Earth. Other than Earth, Mars posses the most highly varied and interesting known terrain in our solar system. The surface of Mars is a very hostile place however it is more like Earth’s surface than any other planet in our solar system.
Much of the Martian surface is rough and cratered, but expansive flat plains and smooth hills can also be found. Unlike any other planet, there is a striking difference between the northern and southern hemispheres of Mars; one is extremely rough and old while the other is young and relatively smooth. The southern hemisphere is strewn with ancient craters of all sizes and is also elevated by a several kilometers creating a visible boundary. On the opposite end the northern hemisphere consists of a wider variety of geological features, but is obviously smoother and much younger. There are large volcanoes, a great rift valley, and a variety of channels.
Volcanism is a geological process that occurs on Earth today, and has on many planetary bodies throughout the history of the solar system. No volcanism is occurring on the surface of Mars today. In the past, however, volcanism was one of the main forces creating and reshaping the surface of the planet. All of the rocks that have been observed by the Viking landers and the Mars Pathfinder Rover are generally agreed to be volcanic in origin.
Tharsis is the largest volcanic region on Mars. It is approximately four thousand kilometers across, ten kilometers high, and contains twelve large volcanoes. The largest volcanoes in the Tharsis region are four sheild volcanoes named Ascraeus Mons, Pavonis Mons, Arsia Mons, and Olympus Mons. The Tharsis Montes (Ascraeus, Pavonis, Arsia) are located on the crest of the crustal bulge and their summits are about the same elevation as the summit of Olympus Mons, the largest of the Tharsis volcanoes. While not the largest of the Tharsis volcanoes, Arsis Mons has the largest caldera on Mars, having a diameter of one hundred twenty kilometers!
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