What are geostationary and polar satellites?

Explanation

The satellite orbiting the Earth have different time periods corresponding to different orbital radii. Kepler.s third law is used to find them radius of the orbit.
`T^(2) = (4pi^(2))/(GM_(E)) (R_(E)+h)^(3) `
`(R_(E)+h)^(3) = (GM_(E)T^(2))/(4pi^(2))`
`R_(E)+h = ((GM_(E)T^(2))/(4pi^(2)))^(1/3)`
Substituting for the time period (24 hours = 86400 seconds ), mass, and radius of the Earth, h turns out to be 36,000 km. Such satellite are called .. geo-stationary satellite .. , since they appear to be stationary when seen from Earth.
India uses the INSAT group of satellite that are basically geo-stationary satellite for the purpose of telecommunication. Another type of satellite which is placed at a distance of 500 to 800 km from the surface of the Earth orbits the Earth from north to south direction. This type of satellite that orbits Earth from North Pole to South Pole is called a polar satellite. The time period of a polar satellite is nearly 100 minutes and the satellite completes many revolution. In the next revolution it covers a different strip of area since the Earth would have moved by a small angle. In this way polar satellite cover the entire surface area of the Earth.