每一颗人造卫星根据其不同目的选用不同的运行轨道。比如，通讯卫星有一个对地静止轨道。这种轨道是与地球自转保持同步的。用于天气预报的卫星的轨道会通过地球的两极。这样，地球表面的每一部分在卫星连续的轨道运行中都被一览无遗。
Each satellite has its own orbit which is selected according to its purpose. Communications satellites, for example, have a geostationary orbit. That is an orbit which turns at the same speed as the rotation of the Earth. Satellites used for weather forecasting pass over the two poles of the Earth. By so doing, a different part of the Earth’s surface is viewed on each successive orbit.
(Source: wwenglish.com)
