The above diagram shows an artificial satellite in a polar orbit. It travels from north to south around one side of the Earth then back to north round the other side. Polar orbital satellites are often very fast moving, completing an orbit within a couple of hours or less. Whilst this is happening, the Earth is spinning so it seems that the satellite is seen to travel in a spiral pathway. This means that it covers a large part of the Earth's surface each day. This sort of orbit is useful for remote sensing satellites e.g. Landsat. The data collected is used to study things like crops, water and air pollution, the impact of industry on the environment and reserves of natural resources such as fossil fuels
The above diagram shows an artificial satellite in a geostationary orbit. It is positioned much further out and orits between the two poles. The orbit may be inclined at an angle to the equator or parallel to it as shown above. Its distance is such that it completes one complete orbit in 24 hours. In the same time, the Earth completed one complete rotation so the net result is that the satellite stays above a single point on the surface of the Earth. This is particularly useful for weather satellites that monitor the weather of a particular area, navigational satellites (GPS - global positioning satellites) and communications satellites.
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