We know that there are nine planets in our solar system: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto. In terms of distance from the Sun, Mars is the fourth planet. It is the outermost of the terrestrial planets and is often called the Red Planet. Do you know why?
We know that Mercury is the planet closest to the Sun. It rises and sets almost with the Sun. Therefore, we can see it either before sunrise or after sunset. Similarly, we see Venus either sometime before sunrise or sometime after sunset (dusk). But Mars can be seen clearly only for a month or two every other year. Among all the planets Mars is next only to Venus in brightness. Also it is very striking not because of its brightness but for its reddish-yellow colour. To study Mars, man has sent many space probes. These spaceships have provided us with many valuable facts about it. In 1976, the American space probes Viking I and II landed on the Martian surface. They gave valuable information about the atmosphere of Mars. It has been found that the atmosphere of Mars contains 1 to 2 percent argon, 2 to 3 percent nitrogen, 95 percent carbon-dioxide and 0.3 percent oxygen.
The surface of Mars appears to be made up of bright and dark areas. About 70 percent of the Martian surface is found reddish and yellowish which gives the planet its characteristic colour. These areas constantly change shape. It has many rocks containing rusty iron and is covered with reddish-brown deserts. The winds blow at very high speeds of about 400 km/hr over Mars and create heavy storms in Martian deserts. The storms raise a lot of red dust in the atmosphere. Since Mars has a weak gravitational pull, these dust particles remain in the atmosphere for weeks together. And so Mars, because of its red dusty surface and the dust particles in the atmosphere, appears reddish orange to us.