Comets originate in two different areas of the solar system. Comets from the Kuiper Belt beyond Neptune are called short-period, since it takes them less time than other comets to go around the Sun. Comets from the Oort Cloud take as long as 30 million years to complete one orbit and are therefore called long-period comets. There are about a trillion comets in the Oort Cloud. The Oort Cloud itself is at the edge of the solar system, almost a quarter of the way from the Sun to the next star, Proxima Centauri.
