Home >> Science & Nature >> Astronomy

Unique Characteristics of Mars

Mars is the outermost terrestrial planet after Mercury, Venus and Earth. The planets beyond Mars are composed almost entirely of gas, without any land formations. There have been 17 successful Mars missions, going back to 1964,

that have resulted in more data on Mars than we have of any other planet in our solar system. "The Red Planet," so called because of the layer of iron oxide dust that covers the surface, has unique characteristics beyond just its color that distinguish it from its planetary neighbors.

Geologic Structure
- Of all the planets in the solar system, Mars is the most like Earth, yet the differences are dramatic.
  
  The surface of Mars is stable in that it is very slow to change, but it is also referred to as chaotic due to its large areas of collapsed terrain and short, tangled collections of ridges and valleys. Unlike Earth, the rocky surface of Mars is not structured in crustal plates that are subject to the destructive tectonic force of subduction, the collision of crustal plates resulting in one being drawn over the other. The large, dry river beds on the surface of Mars are probable evidence that the planet once had flowing water, but it hasn't seen significant precipitation in billions of years.
Largest Volcano
- Mairner 4 was the first successful mission to Mars in 1964, followed by Mariners 6 and 7 in 1969.
  
  Olympus Mons on Mars is the largest shield volcano in the solar system. A shield volcano is a particular type of volcano characterized by its eruptions of low-viscosity lava that forms the volcano's gently sloping sides over a very long period of time. Olympus Mons has a height of over 15 miles (twice the height of Mt. Everest, the tallest mountain on Earth) and is almost 342 miles wide. Mars has three other shield volcanoes that are almost as large. Since the crust of the planet is not made up of tectonic plates, volcanoes occur as single hot-spots; they are not moved away from their magma sources through plate motion. Martian volcanoes remain over their magma source and are active as long as the magma source exists. For this reason, the channeling of lava can take place over billions of years, allowing the volcanoes to build to monstrous size.
Deepest Canyon
- Valles Marineris in Mars is four times the size of the Grand Canyon on Earth.
  
  The deepest canyon in the solar system, Valles Marineris, is on Mars. With a length of 3,000 miles, a width of 435 miles at its widest point and a depth of almost 5 miles, it is four times the size of Earth's Grand Canyon.
Atmosphere
- The dark areas of Mars are the result of massive wind storms.
  
  The atmosphere on Mars has a density less than one one-hundredth that of Earth. The winter gets so cold at the poles that the carbon dioxide (CO2), making up 95.3 percent of the atmosphere, freezes, condensing out of the atmosphere and causing a decrease in atmospheric pressure. The frozen CO2 turns directly into gas through sublimation, a process in which a solid is converted to vapor without going through a liquid state. Strong winds blow from pole to pole. The temperature difference is so extreme from day to night that the wind on the dark side freezes the CO2 and the daylight side vaporizes it. Martian winds of up to 300 mph create the largest dust storms in the solar system.

Astronomy