Mars

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Mars is the fourth planet from the sun, with an orbit next in order beyond that of the earth.

Mars is red in appearance due to oxides in its crust and is easiest to see opposite the sun. . Mars has a diameter of 4,200 miles or 6,800 kilometers, just over half the diameter of the earth, and its mass is only 11% of the earth's mass.

Mars has a very thin atmosphere made up of carbon dioxide, with some nitrogen and argon. Mars has an extreme day-to-night temperature range, resulting from its thin atmosphere, from about 80 degrees Fahrenheit 27 degrees Celsius at noon to about -100 degrees Fahrenheit or -73 degrees Celsius at midnight The high daytime temperatures are only present at less than 3 feet or 1 meter above the surface.

Mars has hot spots under the crust. This may explain volcano activity thought to be on Mars. There is evidence that Mars may have been warmer several billion years ago and that there may have been lakes, rivers, etc. that would have worn away the surface of Mars. Today much of Mars is desert-like.

Mars also has seasons somewhat like the earth. This shows up in the areas of the poles where there are thin polar caps that get smaller during Mars' summers and whiter and bigger during Mars' winters.

Mars is about 141 million miles (228 million kilometers from the sun. It orbits the sun in 687 days, which makes its year twice as long as ours or two of our years. A Mars day or time of rotation on its axis is just about the same as an earth day in length - about 24 hours.

Mars has two moons discovered by Asaph Hall in 1877. The innermost, Phobos, is about 7 miles 11 kilometers in diameter and orbits the planet with a period far less than Mars's period of rotation (7 hours 39 minutes. It to rises in the west and sets in the east. The outer moon, Deimos, is about 4 miles (6 kilometers in diameter.

Planet Mars Videos

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