what is a polar orbit

A polar orbit is an orbit in which a satellite passes above or nearly above both poles of the body being orbited on each revolution. The orbital track of the satellite does not have to cross the poles exactly for an orbit to be called polar, and an orbit which passes within 20 to 30 degrees of the poles is still classed as a polar orbit. Polar orbits are used for Earth-mapping, reconnaissance satellites, as well as for some weather satellites. Satellites in polar orbit look down on the Earth’s entire surface and can pass over the North and South Poles several times a day. Polar orbits are a type of low Earth orbit, as they are at low altitudes between 200 to 1000 km. Launching satellites into polar orbit requires a larger launch vehicle to launch a given payload to a given altitude than for a near-equatorial orbit at the same altitude, because it cannot take advantage of the Earths rotational velocity. Polar orbits are often used for earth-mapping, earth observation, capturing the earth as time passes from one point and reconnaissance satellites, as well as for some weather satellites. The disadvantage to this orbit is that no one spot on the Earth’s surface can be sensed continuously from a satellite in a polar orbit.