what are the uses of geostationary and polar satellites? what are their advantages?
A geostationary satellite is an earth-orbiting satellite, placed at an altitude of approximately 35,800 kilometers directly over the equator, that revolves in the same direction the earth rotates (west to east).
Uses : Direct broadcast TV, Communication network, Defence and intelligence, global positioning or GPS - which is used for satellite navigation systems
Advantage : The satellite remains in the same position throughout the day, and antennas can be directed towards the satellite and remain on track.
A polar orbiting satellite closely parallels the earth’s meridian lines, thus having a highly inclined orbit close to 90°. It passes over the north and south poles each revolution. As the earth rotates to the east beneath the satellite, each pass monitors an area to the west of the previous pass at intervals of roughly 90 to 100 minutes. These strips can be pieced together to produce a picture of a larger area.
Uses : monitoring the weather, observing the Earth’s surface, military uses including spying
Advantage : Polar satellites have the advantage of photographing clouds directly beneath them. They also circle at a much lower altitude (about 850 km) providing more detailed information about violent storms and cloud systems.