Artificial satellites send signals. There are many different kinds of signals they send. Each carries a different type of information.
Some artificial satellites send their signals to radios, telephones, and television sets. These are called communications satellites. Ships, aircraft, and even some cars use navigation satellites to work out their location on Earth. Weather satellites take pictures of the movements of the clouds. Scientific research satellites send information about the universe. Scientists can use an earth observation satellite to look at Earth and find heavily polluted areas or damaged forests. Military satellites can send signals about the movement of missiles, ships, and soldiers.
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