Location and Orbit
Atmosphere and Magnetosphere
Missions to Mars
References & Links
Life on Mars?
Mars: From Surface to Core
Facts in Brief
Due to the short distance between Mars and Earth, astronomers can clearly see surface features of Mars with the aid of telescopes. White ice caps can be seen at the North and South Poles of the planet, shrinking as they near the Sun and growing as they move away. There are noticeable dark and bright areas in these caps. The brighter areas are possibly weathered material, mostly fine dust particles, while the darker areas hide unweathered bare rock. Mars is also known for its great yellowish dust storms. These storms sometimes completely cover Mars for months. At other times, white water vapor clouds are visible.
Many myths have surfaced concerning possible alien life forms on the planet. Who has not heard of the famous face on Mars? The early Viking probes of the 1970's transmitted low-resolution images, particularly in the Cydonia region. Upon release of these computerized photographs, some of which seemed to be a large face, the public quickly accepted these as evidence of a Martian civilization. The Mars Global Surveyor '96, however, provided an enhanced photograph of the region in 1998, confirming that the "face" is simply a hill. Another oddity blown out of proportion includes the canals. Percival Lowell, a very creative writer, suggested that these canali were irrigation canals that brought water to Martian crops. More recent studies, however, prove that these canals are merely optical illusion, caused by the subconscious brain that instinctively draws connections between low-resolution, fuzzy images.
In 1996, a meteorite containing Martian rock crashed into the Earth, and analysts found fossil evidence of life in it. But all known forms of life require water, and no major bodies of water can be found on the Martian surface. Evidence does exist, however, that water may have been present on Mars sometime in its history. If true, the source of it would have probably been icy comets crashing into the planet earlier in its history.
Researchers commonly characterize Mars in terms of its northern and southern hemispheres, because they are so very different in topology. The northern half of the planet contains many large volcanoes and a great rift valley. Interspersed in the large plains are a variety of channels which will be discussed in detail later. This is contrasted with the many impact craters of the south, including the largest impact basin on the planet. Hellas Planitia is approximately 2,000 km across and was probably formed from a meteorite impact. The southern highlands are the oldest terrain on the planet and are, on average, 5 km higher than the northern plains. Consequently, liquid water would run from south to north. On a side note, the highest point on the surface is 30 km higher than the lowest. Also both polar caps have alternating layers of dust and ice, which may have been formed during drastic climate changes.
The channels noted earlier can be classified into three distinct types: channel networks, fretted channels, and outflow channels. These may have been formed when water was still present on Martian surface. Channel networks are very old and indigenous to the southern highlands. Fretted channels are simply eroded preexisting channels. Outflow channels, found at the boundary between the northern and southern highlands, may have been the cause of large floods. The Mars Global Surveyor '96 recently discovered a system of buried flood channels, obviously supporting the existance-of-water theory. Researchers believe, however, that Mars was once a warmer place until its molten core cooled, weakening its magnetic field, which allowed sunlight to parch the planet.
Mars boasts the solar system's largest known volcano, Olympic Mons, 24 km high and 550 m in diameter. One of the most noticeable features in the Tharsis bulge, it is nestled with the lesser Alba Patera, Ascraeus Mons, Arsia Mons, and Pavonis Mons volcanoes--Mars's Himalaya, so to speak. The Tharsis bulge greatly affects Martian weather, so much so as to have possibly changed the planetary rotation! Another notable terrain feature is the Valles Marineris, a great rift valley extending from this region to east-southeast at depths of up to 7 km and widths of up to 700 km.
Very similar to Earth, Mars has a core, a mantle, and a crust. The core is solid iron with nickel and other elements. Molten rock from the mantle formed the much-noticeable volcanoes and rifts. The crust ranges from 15 km at its thinnest to 130 km at its thickest. No active plate tectonics are known to exist on the planet.