Mars

Names for the god of war and called the Red Planet because it looks red when viewed from Earth, Mars is the fourth planet from the sun. This is another of the terrestrial planets, but it does have a very thin atmosphere. There are volcanoes, carters, ice capped mountains, valleys and deserts, making it very similar in physical characteristics to Earth. It is the third smallest planet with a circumference of only about 6700 km. It orbits the sun every 687 days and rotates on its axis every 23.5 hours. The hemispheres of this planet have well-defined seasons because of the tile of its axis.

The surface of Mars is windswept with large boulders. The thin atmosphere does not provide very much protection from the sun’s radiation and has a low insulating effect. This means that the surface loses its heat very quickly with extremes of temperature between night and day. Mars also has a much weaker magnetic field than that of earth, which allows the radiation to penetrate to the surface of the planet.

Carbon dioxide makes up more than 50% of the atmosphere, with very little oxygen. Probes of Mars have reported that the southern hemisphere of the planet has less water vapor than the northern hemisphere and there are polar ice caps. Powerful winds constantly disturb the atmosphere with speeds of up to 175 km per hour being the norm. Winds can reach speeds of 500 km per hour.

There are many mountains on Mars, but there are no oceans. Space probes have not found any evidence that water exists on this planet, but there is evidence that it did exist at one time in the winding features that resemble the path of rivers. Very large craters cover nearly half of the surface and like on Earth, there are volcanoes and relatively flat stretches of terrain. In the middle of the planet there is a huge canyon stretching for over 400 km and with a diameter of over 500 km.

Mars has two satellites, named Phobos and Deimos. Phobos revolves around the planet faster than the planet rotates on its axis. Deimos is father away from the planet and revolves around Mars once every 30 hours. Throughout its revolution around the sun, there are times when Mars comes quite close to Earth. This usually occurs at 15-17 year intervals, with the next one expected in 2010.