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Distance from sun 227.94 million km, 1.523 a.u.
Diameter 6786 km, 0.532 times earth's diameter
Mass 0.1074 times earth's mass
Density 3.95
Gravity 0.379 times earth's gravity, escape velocity 5.0 km/s
Rotation 24.6229 hours
Orbit Eccentricity 0.0934
Orbit Inclination 1.85 degrees
Axis Tilt 25.19 degrees
Sidereal Period 686.98 Earth days
Synodic Period 779.94 Earth days

History: Mars has the most distinct color of any of the planets. Its blood red color led the ancients to name it after the Mars, the roman god of war. In alchemy Mars was associated with the metal iron. It is also the only planet to have a star named after it, Antares, "rival of mars." Late in the nineteenth century, scientists discovered lines on the Martian surface, which they believed to be canals dug by a martian civilization.

Description: Mars is known to have a desert like surface with a wide variety of topographic features. Pictures taken of the Martian surface reveal meteorite impacts, huge valleys, and volcanic mountains, all of which dwarf those found on earth. Mars's largest valley, Valles Marinaris, is longer than the United States is wide, some 3,000 miles. The tallest mountain, Olympus Mons, is the largest known volcanoe in the solar system, it wider than the state of Arizona and is more than three times as tall as the volcanoes of the Hawaiian Islands. The Martian atmosphere is much thinner, only 70 percent of what it is here on earth. It consists mostly of carbon dioxide and the rest is nitrogen and argon. The planet is to small to hold a substantial atmosphere, yet dust storms occur on Mars that cover a whole hemisphere, generating winds around 100 miles an hour. Temperature varies depending on the latitude on Mars, but even at the equator temperatures are well below freezing. Mars has polar ice caps resembling those on earth, but the martian ones consist of frozen water and dry ice (frozen carbon dioxide). The axil tilt of Mars is much like that of earth, therefore Mars experiences seasons much like those on earth. These seasons are, however, slightly longer than those of earth.

Observation: The synodic period of Mars is about two and a quarter earth years. At opposition, when Mars is opposite of earth from the sun, it is at its brightset, shining brighter than any star, which reveals its red color. Because of the eccentricity of its orbit, Mars varies anywhere from 35 to 63 million miles from earth at this time, so its brightness depend on whether it is at perihelion or apihelion. The planet is at perihelion every 17 years, when it is at its brightest and largest size, about 25 minutes across. At opposition, it rises at sunset and stays up all night. Directly after opposition, it rises at sunset and sets around midnight. After opposition, it rises at midnight and is up the rest of the night. A medium size telescope will detect some surface features of Mars, including the white polar ice caps.


Mars: Global View
Olympus Mons

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