Most satellites are made and operated by commercial companies. There are a number of different types; navigation, communication, scientific, military and Earth-monitoring. The first of them started working for us over 40 years ago.
Communication satellites are such a part of everyday life, we use them without realizing it. A sporting event or pop concert happening at one place can be seen by people on the other side of the world at the same time. Cameras film the action, the TV signal is beamed to a satellite above the event, the signal is relayed round Earth by satellites until it reaches one above the opposite side of the planet. The signal is sent down to Earth where it is received and the event watched. Millions of telephone conversations and communications on the Internet, are also handled this way.
Our daily weather forecasts use information from weather satellites that are positioned around the globe. They observe the cloud patterns, monitor Earth's atmosphere, record its temperature range and look out for storms. The whole of Earth's surface has been imaged many times by satellites studying Earth's natural resources such as its forest, icecaps and oceans. They reveal short- and long-term changes to the planet.
Military satellites can be used for spying on other countries, guiding missiles, or being a weapon themselves. Navigation satellites pinpoint any position on Earth and are an invaluable aid to navigators on land, sea and in the air. Astronomical satellites such as the Hubble Space Telescope look into space and give us spectacular views of the stars and galaxies.
Communication satellites are such a part of everyday life, we use them without realizing it. A sporting event or pop concert happening at one place can be seen by people on the other side of the world at the same time. Cameras film the action, the TV signal is beamed to a satellite above the event, the signal is relayed round Earth by satellites until it reaches one above the opposite side of the planet. The signal is sent down to Earth where it is received and the event watched. Millions of telephone conversations and communications on the Internet, are also handled this way.
Our daily weather forecasts use information from weather satellites that are positioned around the globe. They observe the cloud patterns, monitor Earth's atmosphere, record its temperature range and look out for storms. The whole of Earth's surface has been imaged many times by satellites studying Earth's natural resources such as its forest, icecaps and oceans. They reveal short- and long-term changes to the planet.
Military satellites can be used for spying on other countries, guiding missiles, or being a weapon themselves. Navigation satellites pinpoint any position on Earth and are an invaluable aid to navigators on land, sea and in the air. Astronomical satellites such as the Hubble Space Telescope look into space and give us spectacular views of the stars and galaxies.
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