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Old 12-03-2012, 07:37 PM   #62
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Lightbulb Asteroid belt/Mars/Earth

The asteroid belt is the region of the Solar System located roughly between the orbits of the planets Mars and Jupiter. It is occupied by numerous irregularly shaped bodies called asteroids or minor planets.

Size comparison of Earth and Mars. Mars has approximately half the diameter of Earth.

Mars is the fourth planet from the Sun in the Solar System. Named after the Roman god of war, Mars, it is often described as the "Red Planet" as the iron oxide prevalent on its surface gives it a reddish appearance. Mars is a terrestrial planet with a thin atmosphere, having surface features reminiscent both of the impact craters of the Moon and the volcanoes, valleys, deserts, and polar ice caps of Earth. The rotational period and seasonal cycles of Mars are likewise similar to those of Earth, as is the tilt that produces the seasons. Mars is the site of Olympus Mons, the highest known mountain within the Solar System, and of Valles Marineris, the largest canyon. The smooth Borealis basin in the northern hemisphere covers 40% of the planet and may be a giant impact feature.

One of the most striking things about Mars is that its two halves are quite different. Most of the southern hemisphere is marked by ancient cratered highlands, similar to those on the Moon. The northern hemisphere, in contrast, is dominated by lava-filled plains that reveal a more complex history of activity and change. At the boundary between the two types of terrain is an abrupt shift in of several kilometers. Scientists still aren't sure about the origin of this sharp boundary and the two contrasting hemispheres. One idea is that Mars suffered a massive impact .

From Earth, the northern plains of Mars look paler than the rest of the planet and were once thought to be continents. Consequently, they were given names such as Utopia Planitia (plain of Utopia) and Arabia Terra (land of Arabia). The darker features in the south were believed to be seas and so were given names such as Mare Erythraeum, Mare Sirenum, and Aurorae Sinus.

Last edited by lightgiver; 12-03-2012 at 07:44 PM.
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