Question

What is

1. Polar orbit
2. Equatorial orbit
3. Geostationary orbit ?

Why communication satellites placed in a geostationary orbit.

Answer 1

Polar orbit:

1. A polar orbit is one in which a satellite passes above or nearly above both poles of the body being orbited on each revolution.
2. It has an inclination of about 60° - 90° degrees to the body's equator.
3. A satellite in a polar orbit will pass over the equator at a different longitude in each of its orbits.

Equatorial orbit:

1. A equatorial orbit is an orbit that lies close to the equatorial plane of the object orbited.
2. Such an orbit has an inclination near 0°.
3. On Earth, such orbits lie on the celestial equator, the great circle of the imaginary celestial sphere on the same plane as the equator of the earth.

Geostationary orbit:

1. A geostationary orbit is also referred to as a geosynchronous equatorial orbit.
2. It is a circular geosynchronous orbit of 35,786 km in altitude above the earth's equator and following the direction of earth's rotation.

Communications satellites are often placed in a geostationary orbit so that earth-based satellite antennas (located on Earth) do not have to rotate to track them but can be pointed permanently at the position in the sky where the satellites are located.