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Mars

The Red Planet

Mars is the fourth planet from the Sun and is commonly referred to as the Red Planet. The rocks, soil and sky have a red or pink hue. The distinct red color was observed by stargazers throughout history. It was given its name by the Romans in honor of their god of war. Other civilizations have had similar names. The ancient Egyptians named the planet Her Descher meaning the red one. Before space exploration, Mars was considered the best candidate for harboring extraterrestrial life. Astronomers thought they saw straight lines crisscrossing its surface. This led to the popular belief that irrigation canals on the planet had been constructed by intelligent beings. In 1938, when Orson Welles broadcasted a radio drama based on the science fiction classic War of the Worlds by H.G. Wells, enough people believed in the tale of invading Martians to cause a near panic.

The first spacecraft to visit Mars was Mariner 4 in 1965.





Several others followed including Mars 2, the first spacecraft to land on Mars and the two Viking landers in 1976. Ending a long 20 year hiatus, Mars Pathfinder landed successfully on Mars on July 4th 1997 . In 2004 the Mars Expedition Rovers "Spirit" and "Opportunity" landed on Mars sending back geologic data and many pictures; they are still operating after more than three years on Mars. In 2008, Phoenix landed in the northern plains to search for water. Three Mars orbiters (Mars Reconnaissance Orbiter, Mars Odyssey, and Mars Express) are also currently in operation.

Right: The site of the Vicking 2 landing in 1976

Left: The site of the Pathfinder landing in 1997

 

Mars is 4220 miles (6791 km) in diameter (Earth - 7926 miles). It has one-tenth the mass of Earth, being less dense, however, its surface area is only slightly less than the total area of Earth's dry land. Gravity is 0.38 that of Earth, which means that if you weigh 100 pounds or kg on Earth, you would weigh 38 pounds or kg on Mars. Gravity is one of the problems future human missions to Mars will have to deal with, since living in a low-gravity environment will cause problems for human health.

Mars is a cold planet with temperatures droping as low as -133 deg Celsius (-207 deg Fahrenheit). Occasionally at the equator the temperature of the surface can rise to above the melting point of ice which is 0 deg Celsius (32 deg Fahrenheit). Due to great temperature variations occasionally vast dust storms occur on Mars that can cover almost the entire planet. One of such dust storms happened during the Mars Exploration Rover Mission. Mars rovers Spirit and Opportunity hardly survived that harsh environment.

The martian day is only 41 minutes longer than a day on Earth and scientists beleive that Mars was once very similar to our planet with evidencs that liquid qater once existed on the red planet's surface.

 

The Martian Atmosphere

It was once believed that Mars had an atmosphere much like Earth's and that if we could find a way to get there, we could breath Martian air. As often happens, knowledge brings a new outlook. Composition of the Martian air is 95% Carbon Dioxide, 3% nitrogen and trace amounts of oxygen and water. The density of the Martian atmosphere is only 1% of Earth. One surprise was the pale yellowish-pink sky rather than the blue we are so accustomed to. Our sky is blue because incoming sunlight is scattered by the gas molecules in our atmosphere. Blue light is scattered the most, and that is why we see a blue sky. Mars sky is pinkish-orange because dust particles scatter light even more. It is believed that dust particles are suspended in the atmosphere all the time, instead of just when there is a dust storm. The presence of all that dust would further scatter the sunlight giving the Martian sky that characteristic color. With all that Carbon Dioxide in Mars' atmosphere, you might expect to find a runaway greenhouse effect like that on Venus, but it is not the case. Mars density is so low that the carbon dioxide creates only a minor greenhouse effect. And Mars is so cold that clouds of dry ice (frozen CO2) and some water crystals drift about in the Martian atmosphere.





Facts about Mars

  • Mars has the biggest mountain in the solar system - Olympus Mons is a dormant volcano and reaches 15.5 miles high 372 miles across. (Mt Everest is between 5 and 6 miles high)

  • People always wondered about life on Mars because of the numerous canals - This is why we have always imagined alien invaders coming from there, and not Jupiter or Venus. Actually, Mars is one of the least habitable planets, with freezing temperatures, solar winds, and almost no atmosphere.

  • Mars is named after the Roman god of war because its red color reminded early observers of blood - The reason for the red color is that the soil is composed of iron oxide, or what we commonly call rust.

  • When compared to other planets in our solar system, Mars is quite small - It is half the size of earth. Mars has about a third of the earth's gravity, which means that you can jump three times as high.

  • In the 1970's, the Viking orbiter took pictures of what appear to be giant faces and pyramids carved into the planet's surface in the Cydonia region - The biggest image resembles that of a Sphynx but scientists insist that these images are eroded hills.

  • Mars has 2 moons and one is on a collision course with the red planet - The moon Phobos orbits dangerously close to Mars' atmosphere. Someday, the gravitational pull with smash the moon to bits. The debris will stay in Mars' orbit, making a ring like the rings of Saturn. Eventually, it will rain down on Mars.

  • Only 1/3 of all the missions to Mars have been successful - So many missions have disappeared that it has led scientists to wonder if something strange is happening. They refer to Mars as the 'Bermuda Triangle' of the solar system.

Left: Olympus Mons, The largest mountain in our solar system (click on the image to enlarge)





 

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