108 The Oort Cloud and Kuiper Belt
The Oort Cloud is a hypothesized spherical cloud of icy objects up to 50,000 AU from the sun. This spherical cloud is the primary source of long-period comets. No Oort Cloud objects have been found, to date. Any object within the Oort Cloud would be called an Oort Cloud Object, (OCO) . The Oort Cloud would represent the physical boundary of the solar system.