Types of Artificial Satellites: Depending upon the distance from the Earth surface and the uses, artificial satellites are divided broadly into two categories:
(i) Geo Stationary Satellite:
Every satellite moves around the earth in its fixed path called orbit. Any satellite which is moving around the earth but when seen from the earth it looks stationary is called Geo Stationary Satellite. This satellite is located at approx. 36000 km. height from the earth’s surface. These satellites move in equatorial orbit. The revolutional period of Geo-stationary satellite is equal to the rotational period of earth hence its direction of movement is like earth i.e. west to east it completes its one revolution around the earth in 24 hours in its own orbit. Hence it looks stationary when seen from earth. It is used in satellite, telephone, television, radio and in other global communication so, it is also called communication satellite.
(ii) Polar Satellite:
Those satellites which move in Polar orbit on earth are called Polar Satellites. They have distance from earth’s surface 500-800 km. They give information about atmosphere like – Ozone layer, pictures of clouds etc. Informations given by Polar satellites are remote sensing and important to study weather and environment. The important is that Polar satellites can observe whole earth with the help of their cameras twice in a day. Those satellite that get information about any thing or substance without coming in contact of it is called remote sensing. India has launched many Remote sensing satellites like – IRS – IA, IRS-2B, IRS-3C etc. micro waves and radio waves can travel in vacuum i.e. without medium.