Beyond Neptune and extending beyond the orbit of Pluto is the Kuiper Belt. This is home to a number of small icy objects and the source of short term comets. There is strong support for Pluto not being a true planet, but a large Kuiper object, becaues of its unusual orbit. Even further out is the Ort Cloud where most comets orbit the Sun. The Ort Cloud is the source of all long term comets. No comet has ever been found that came from intersteller space, all are objects orbiting our Sun.
