SOLAR SYSTEM

Detailed explanation-1: -Long-period comets (which take more than 200 years to orbit the Sun) probably come from the Oort Cloud, which is sometimes described as a “cometary reservoir."

Detailed explanation-2: -The outer Oort cloud is only loosely bound to the Solar System, and thus is easily affected by the gravitational pull both of passing stars and of the Milky Way itself. These forces occasionally dislodge comets from their orbits within the cloud and send them toward the inner Solar System.

Detailed explanation-3: -The Kuiper Belt shouldn’t be confused with the Oort Cloud, which is a much more distant region of icy, comet-like bodies that surrounds the solar system, including the Kuiper Belt. Both the Oort Cloud and the Kuiper Belt are thought to be sources of comets.