Low Earth Orbit (usually abbreviated LEO) is any orbit that is between 200 and 500 miles above the surface of the Earth. At that altitude, objects travel at 17,000 mph (27,359 kph) and circle the planet every 90 minutes. It is the most popular orbit to place satelites in, as it is relatively inexpensive to get to and it gives the best view of the planet Earth. As of 1999, the USSC has identified more than 8,000 objects in Low Earth Orbit that are the size of a softball or larger.