third term english exam TCL
Satellites are devices which orbit the earth. Their most common uses are communication - to transmit television pictures and telephone calls - and navigation. Many satellites orbit the earth every 24 hours, so they are always over the same place. There are thousands of satellites orbiting the earth. Some are 36,000 kilometers above the earth.
Using satellites to transmit television pictures means that people all over the world can watch programmes from other countries. Satellites can transmit hundreds of channels of high quality. Although most mobile phones today use radio signals, there are now satellite phones which can be used in places with no radio signals.
Sat-nav, which is short for satellite navigation, is an electronic device which can help car drivers and pilots to know exactly where they are. If you have sat-nav in your car, it can tell you your best route and help you to avoid traffic jams. Many drivers today prefer to use Sat-nav or GPS – Global Positioning System- to reach the destinations they are not familiar with.
Satellites have made it easier to forecast the weather accurately, and to warn people about forest fires or floods through weather forecast programmes on TV. Photographs from high in space can also help produce up-to-date maps. In poor parts of the world, photographs from space can help farmers to plan for the future. There are already many different uses for satellites. It is certain their use will increase in the years to