Many Earth-orbiting satellites are in polar, circular orbits, with inclinations near 90 degrees.
Typically, these satellites are in low Earth orbit and thus have periods of about 1 1/2 hours, so that the ground trace of such a satellite takes just a few days to pass over the whole surface of the Earth.
These satellites, such as the Landsat satellites for example, are useful for observing the weather and mapping Earth resources.
Some satellites are in orbits with an inclination of 98 degrees. These orbits are called "Sun Synchronous" because they pass over a certain spot on the Earth at the same local time every day. This is because the satellite's westward motion just keeps up with the Sun's westward motion when the orbital inclination is 98 degrees.Click here to return to the Lesson Map