Satellites have two main categories of orbit around the Earth: geostationary and polar orbiting.
Geostationary satellites are satellites that face the same location at all times, but they are not in fact stationary. Because the Earth is moving, geostationary satellites must match the speed of Earth’s rotation in order to stay facing the same location. This means they use the Earth’s orbit, which puts them on a plane with the Earth and Sun. From this perspective, they face the sides of the Earth, but cannot “see” the poles. Geostationary satellites are quite far away so they can “see” more of the Earth at once—usually a whole hemisphere.
Polar orbiting satellites, as the name suggests, pass over the North and South Pole as they orbit the Earth. Thus, their orbit is perpendicular to that of geostationary satellites. Polar orbiting satellites are usually much closer to Earth and move quickly, usually in a Sun-synchronous orbit. A Sun-synchronous orbit is timed with the Sun such that the satellite can “see” the same location at the same time. For example, a polar orbiting satellite may pass over Washington at 9am, then pass over the North Pole, then pass over Russia, then India, then the South Pole, then South America, then California, then passing over Washington again at 9am the next day.
Geostationary and polar orbiting both have pros and cons. Geostationary satellites are able to gather data about the same location over time, but are only able to “see” one location. Polar orbiting satellites can gather data about many different locations, but are less useful for assessing how one place may change over time.
Because geostationary satellites are far away, they can collect data on a lot of the Earth at once—usually a whole hemisphere. However, they cannot collect data on the poles, and because they’re far away, their images are lower resolution and their data may be less detailed. Resolution refers to the clarity and detail in an image. Polar orbiting satellites are closer and so provide higher resolution images and data with higher levels of detail. They can also collect data on the poles. They cannot, however, see much of Earth at a time, so their pictures and data must be pieced together.