All satellites orbit the center of the Earth.

• Some stay above the equator all the time.
• Others go from one pole to another.

Scientists need a way to identify the path followed by a satellite. They use a system call inclination. The inclination of a satellite is the highest latitude line the satellite passes over during its orbit.

• If a satellite has an eastward orbit that stays above the equator all the time, its inclination is 0 degrees.
• If a satellite orbits north and south, passing over both poles, its inclination is 90 degrees.
• All other orbits have inclinations that are between 0 and 90 degrees.

The Space Shuttle usually has an inclination of about 30 degrees. This means that it circles the center of the Earth, moving back and forth between 30 degrees north of the equator and 30 degrees south of the equator.