Pluto used to be classed as a planet of the solar system, but is now considered to be a dwarf planet, and a part of the Kuiper belt. The Kuiper belt is a vast collection of dwarf planets, asteroids, rocks, ice and dust that circle the sun, that extends for millions of miles beyond Neptune, on the outskirts of the solar system.
As of mid-2008, five smaller objects are classified as dwarf planets, all but the first of which orbit beyond Neptune. These are:
Ceres (415,000,000 km from the sun)
Pluto (5,906,000,000 km, from the sun, formerly classified as the ninth planet)
Haumea (6,450,000,000 km from the sun)
Makemake (6,850,000,000 km from the sun)
Eris (10,100,000,000 km from the sun)
