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MARS
A rust covered planet, the fourth from the sun and the last of the four terrestrial worlds in the solar system.
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Mars is much like Venus-- it's very bright and therefore easily spotted in the night sky. Because of this, we don't know who exactly discovered Mars. We do know it was named after the Roman god of war, because its reddish color reminded people of blood.
In 1659, Christian Huygens discovered a strange feature on the surface of the Red Planet. It was later called the Syrtis Major. Fear of Martian invasion has been in society ever since. In 1802, one scientist was so convinced there was life on Mars that he wanted to draw huge figures in the snow to signal the Martians.
In 1877, astronomer Giovanni Schiaparelli discovered what he believed to be several lines crossing one another. He claimed they were water canals made by intelligent creatures. His work spawned many science fiction books and movies, such as H.G. Wells' War of the Worlds. Eventually, we sent spacecraft to investigate the Red Planet.
In 1971, Mariner 9 visited Mars and sent back images of enormous volcanoes and vast canyons. It discovered Olympus Mons, now the most famous volcano not on Earth. This massive volcano could cover the state of Missouri, and reaches 15 miles above the surface! Mariner 9 also found evidence that water once flowed on Mars. However, there were no sightings of Schiaparelli's famous canals.
In 1975, two spacecraft named Viking I and II landed on Mars to study its surface. They analyzed the rocks and soil of the planet while providing us with information about its atmosphere and weather patterns. Even today we are exploring Mars. The Mars Global Surveyor made a detailed 3-dimensional map of the planet. Unfortunately, the loss of the Mars Climate Orbiter and the Mars Polar Lander has been a big setback in our research.
In 1877, astronomer Asaph Hall spotted the two moons and named them Phobos, which means fear, and Deimos, which means panic. They were named after the mythical horses that drew the chariot of the Roman god, Mars.
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 The uniquely red global surface of Mars is marked by many interesting features - some like those on the Earth and others strangely different. The reddish color is caused by rust (iron oxide) in the soil.
Some of these features are; volcanoes, canyon systems, river beds, cratered terrain, and dune fields.
Of these features, the most interesting includes the apparently dead volcano Olympus Mons, which rises 23 km (~75,000 ft) above the surrounding plains and is the highest known peak in the Solar System. Valles Marineris is a giant canyon system that runs about 2,500 miles across the surface of the planet and reaches depths of 6 km or 4 miles (for comparison, the Grand Canyon is not more than 1 mile deep).
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The atmosphere of Mars is much thinner than that of Earth, with a surface pressure averaging 1/100th that at the surface of the Earth. Surface temperatures range from -113oC at the winter pole to 0oC on the dayside during summer.Although the length of the Martian day (24 hours and 37 minutes) and the tilt of its rotational axis (25 degrees) are similar to the values for these parameters on Earth (24 hours and 23.5 degrees), the eccentric orbit of the planet about the Sun impacts the lengths of the seasons the most. The atmosphere is composed mainly of carbon dioxide (95.3%), nitrogen (2.7%), and argon (1.6%), with trace amounts of other gases. Oxygen, which is so important to us on earth, makes up only 0.13% of the atmosphere at Mars. There is only one-fourth as much water vapor in the atmosphere.Although small, this is thought to be enough to allow water ice to be frozen into the near subsurface at mid to high latitudes. With so little water, clouds are rarely seen in the Martian sky. The possible role in the distant past of liquid water in forming the dry river beds which we can see is still unknown, particularly because water ice is not plentiful on the surface of the planet.
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Planet
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Diameter: 6,794 km
Mass: 0.64191 x 1027 g
Density: 3.94 gm/cm3
Name in Roman/Greek Mythology: Ares
Surface Gravity: 371 cm/s2
Temperature Range: 186 to 268 K
Average Surface Temperature: 218 K
Number of Satellites: 2
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