The Oort Cloud is a vast, hypothetical region located far beyond Neptune, considered to be the source of long-period comets. It is thought to be a spherical cloud surrounding the solar system, extending up to 100,000 AU (astronomical units) from the Sun. The Oort Cloud is divided into two regions: the inner Oort Cloud and the outer Oort Cloud.
Though no spacecraft have reached the Oort Cloud, its existence is inferred from the behavior of comets that orbit the Sun. The Oort Cloud is an important part of the solar system’s structure and understanding it could offer insights into the early solar system and the formation of planetary bodies.