According to the Nice theory, The Kuiper belt lies out past the orbit of Pluto. Instead of asteroids, The Kuiper belt has millions of icy comets that circle the Sun very fast, and because of that fast motion, they were flung outward by encounters with the giant planets. Scientist believe that the comet Pluto is a part of the Kuiper belt. The Oort cloud is not really a cloud, but a mass of a over a trillion comets that circle the Sun at a great distance. In fact, the Oort cloud extends over 13,000,000.000.000 miles from the Sun. Unlike the Kuiper Belt, the comets in the Oort Cloud circles around the Sun in every direction. They do not stay on the same plane. Scientist believe that the Oort cloud formed as trillions of comets were thrown out
