• Satellites are the objects that orbit a planet.
• The moon is a natural satellite.
• Artificial satellites are man-made objects that orbit the Earth.
• In order to launch satellites into space, we need to overcome the Earth's gravity.
• This is achieved by launching satellites by powerful rockets.
• The first artificial satellite was Sputnik I launched by the Soviet Union in 1957.
• Now almost fifty years later, there are thousands of satellites orbiting the Earth at various heights.
• Most Indian satellites are also launched like: INSAT ones- named INSAT-1A, INSAT-1B, 1C, 2A, 2B, 2C etc.
• There's also Kalpana 1, a meteorological satellite formerly called MetSat1, GSAT which is an experimental satellite and Edusat which is an educational satellite broadcast channel.
Figure 20: (a) Artificial satellite orbiting the Earth
(b) Artificial satellite
• There are different types of satellites, each designed for a specific purpose like:
(1) Communication satellites send signals for T.V. and radio programmes and telephone calls.
(2) Navigation satellites help ships and aircraft find their way.
(3) Astronomy satellites carry telescopes into space.
(4) Weather satellites help in weather forecasting.
• Ground stations on Earth send and receive signals to and from these satellites.