mars

 

mars the fourth planet from the Sun and the second smallest planet in the Solar System, after Mercury Romans then did likewise, associating the planet’s blood-red color with Mars, their own god of war. Mars is the fourth planet from the Sun. Named after the Roman god of war, and often described as the “Red Planet” due to its reddish appearance.

 

composition

with a thin atmosphere composed primarily of carbon dioxide.Martian surface gravity is only 37% of the Earth’s (meaning you could leap nearly three times higher on Mars).Its mass is 0.107 Earth masses and its gravity is about 62 percent less than Earth’s gravitational tug. That means you would weigh less on Mars than you do on Earth.

The Martian atmospheric pressure is about a hundred times less than Earth’s, almost completely carbon dioxide with a few traces of nitrogen, oxygen, and water vapor.  the temperatures on Mars never get much warmer than 20 C at noon on the equator. It’s more likely to be below around most of the time, with wintertime measurements as low as -153 C in polar wintertime.Clearly there has been volcanic activity in the past, eruptions that built Olympus Mons and the other volcanoes that rise up from the rusty red surface.
      Today mars shows us a dry, dusty, rocky surface.divided into the south and north poles, the southern half of the planet is much more rugged, with many more craters and highlands while The northern half of Mars has more smooth  dry lake-beds and sinuous riverbeds and it is suspected that long-gone oceans and lakes explain the smoothness of some areas, while the motion of long-melted glaciers may have carved out interesting terrain in other places. There are ice caps at both poles that grow and shrink with the change of seasons. This difference in surface characteristics is called the Martian dichotomy. Impact craters account for part of the dichotomy, the Planet has a solid iron core, which is believed to help generate the planet’s weak magnetic field.

mars' thin atmosphere may be the result for its depreciating habitability
The lack of a magnetosphere and extremely thin atmosphere of Mars are a challenge: the planet has little heat transfer across its surface, poor insulation against bombardment of the solar wind and insufficient atmospheric pressure to retain water in a liquid form (water instead sublimes to a gaseous state), its soil nutrients may be able to support life, but life would still have to be shielded from the intense ultraviolet light which the absence of atmosphere couldn't solve.the planet's thin (low-pressure) atmosphere prevents liquid water from existing over large regions for extended periods. The past flow of liquid water demonstrates the planet's potential for habitability. Some recent evidence has suggested that any water on the Martian surface may have been too salty and acidic to support regular terrestrial life.
    in the past it was much warmer, wetter and thicker, at some point, the atmosphere began to escape to space, and the Mars surface water began to disappear. 
     the solar wind interacts directly with the Martian ionosphere, lowering the atmospheric density by stripping away atoms from the outer layer.The atmosphere of Mars consists of about 96% carbon dioxide, 1.93% argon and 1.89% nitrogen along with traces of oxygen and water, quite dusty and containing particulates about 1.5 µm in diameter which give the Martian sky a tawny color when seen from the earth surface