Figure 5-6 The Kuiper Belt and Oort Cloud (a) The classical Kuiper belt of comets spreads from Neptune out 50 AU from the Sun. Most of the estimated 200 million Kuiper belt comets are believed to orbit in or near the plane of the ecliptic. The spherical Oort cloud, containing billions of comets, extends out beyond the Kuiper belt. (b) Positions of known bodies in the Kuiper belt and Oort cloud.