Deep Into the Solar System

One important region is the Kuiper Belt. It lies just beyond Neptune and contains many small, icy objects and dwarf planets like Pluto. These objects are leftovers from the early solar system and orbit the Sun in a flattened, disk-like shape. Many short-period comets come from this area.

 Far beyond the outer planets of the Solar System, lies the mysterious outer region known as the Oort Cloud. It is thought to be a huge, spherical shell of icy bodies and debris that surrounds the solar system at an enormous distance, far beyond the orbit of Pluto and the Kuiper Belt. Scientists believe the Oort Cloud is the source of many long-period comets that occasionally travel into the inner solar system when their orbits are disturbed. Because it is so far away, no spacecraft has ever reached it, and it has not been directly observed, but its existence is supported by studying the paths of comets. Temperatures there are extremely cold, and objects in the Oort Cloud are mostly frozen remnants from the early formation of the solar system.

Even beyond that is the Heliosphere, which is not made of rocks or planets but of charged particles from the Sun. It forms a huge protective bubble around the solar system, and at its edge is the boundary where the Sun’s influence weakens and interstellar space begins.