Satellite

Ten, nine, eight, seven... lift off. I think you have heard these words. These words would sound like music to an astronomer's ears. As the countdown progresses, the rocket's engines fire and give it the required push to tear the atmosphere of the earth's gravitation. These rockets take astronauts, artificial satellites or man made satellites in to the space. It is said that a satellite rotates around the earth and the gravitational pull of the earth like an invisible rope keeps the satellite from flying away.

Why does a satellite come down?
At one point, the satellite loses its speed, making the gravitational pulling it away. This makes the satellite come crashing down to the earth. Most of the material gets burnt even before it reaches earth because of the intense heat generated due to friction with the atmosphere. These satellites are works on solar cells which directly absorb light from the sun.

The first artificial satellite is SPUTNIK- 1. Satellites are mostly used for tele-communication purposes. Many countries have their own satellites for Defence purpose, so that they can protect themselves without any other countries idea.