University of Edinburgh

BSL Astronomy Glossary - dwarf planet - definition

Definition: Like planets, dwarf planets are naturally occurring objects that orbit the sun in our solar system. They are much smaller than the eight planets, such as Earth, and one example of a dwarf planet is Pluto. When it was discovered in 1930, scientists labelled it as a planet but it was re-categorised as a dwarf planet in 2006 partially because of its size.