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<a href='/solarsystem/sun/index.html'>sun</a> Sun
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earth Earth
mars Mars
jupiter Jupiter
saturn Saturn
uranus Uranus
neptune Neptune
pluto Pluto
Planet Stats
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A Light Year

Mars is our second closest neighbor after Venus.

The Planet Mars

Mars is the 4th planet from the Sun, and one of the 5 planets visible with the unaided eye. When Mars is closest to the Earth, it becomes one of the brightest stars in the sky, appearing bright and red. Because of this bright red color, ancient peoples associated Mars with blood and war. The ancient Romans named Mars after their god of War, the same persona as the Greek god Ares. The symbol for Mars also represents the god of War.

Mars orbits the Sun at an average distance of 228 million km, which is about 1.5 times the distance of the Earth to the Sun. Earth and Mars can get as close as 54.6 million km apart, making Earth the closest planet to Mars.

The size of Mars makes it the third largest terrestrial planet, after Earth and Venus. The diameter of Mars is 6,792 km across. This is about half the diameter of Earth. The mass of Mars is even lower; the planet has a mass of 6.42 x 1023 kg, which gives it a mass of only 10% compared to Earth. This lower mass gives Mars a much lower gravity. If you could stand on the surface of Mars, you would experience about 38% the force of gravity that you experience on Earth. The volume of Mars is only 15% the volume of Earth.

We know that Mars is a small rocky body once thought to be very Earth-like. Like the other "terrestrial" planets - Mercury, Venus, and Earth - its surface has been changed by volcanism, impacts from other bodies, movements of its crust, and atmospheric effects such as dust storms. It has polar ice caps that grow and recede with the change of seasons; areas of layered soils near the Martian poles suggest that the planet's climate has changed more than once, perhaps caused by a regular change in the planet's orbit. Martian tectonism - the formation and change of a planet's crust - differs from Earth's. Where Earth tectonics involve sliding plates that grind against each other or spread apart in the seafloors, Martian tectonics seem to be vertical, with hot lava pushing upwards through the crust to the surface. Periodically, great dust storms engulf the entire planet. The effects of these storms are dramatic, including giant dunes, wind streaks, and wind-carved features.

Mars has two moons named for the mythological sons of Ares, the Greek counterpart of the Roman god, Mars. Phobos means fear or panic (think "phobia"), and Deimos means flight (as in running after an overwhelming defeat). Fitting names for the sons of a war god.

Mars' moons are among the smallest in the solar system. Phobos is a bit larger than Deimos, and orbits only 6,000 km (3,700 miles) above the Martian surface. No known moon orbits closer to its planet. It whips around Mars three times a day, while the more distant Deimos takes 30 hours for each orbit. Phobos is gradually spiraling inward, drawing about 1.8 meters closer to the planet each century. Within 50 million years, it will either crash into Mars or break up and form a ring around the planet.

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