Dwarf planet

Definition

A dwarf planet is a celestial body that orbits the Sun and has sufficient mass for its self-gravity to assume a nearly round shape, but has not cleared its neighboring region of other objects. It differs from a planet in that it does not dominate its orbit.

5 Must Know Facts For Your Next Test

1. Pluto was reclassified from a planet to a dwarf planet by the International Astronomical Union (IAU) in 2006.
2. Dwarf planets, like Pluto, are part of the Kuiper Belt, which is a region beyond Neptune filled with small icy bodies.
3. Charon, Pluto's largest moon, is so large relative to Pluto that they are sometimes considered a double dwarf planet system.
4. As of now, there are five officially recognized dwarf planets in our solar system: Pluto, Eris, Haumea, Makemake, and Ceres.
5. Unlike planets, dwarf planets have not cleared their orbital paths of other debris.

Review Questions

• What distinguishes a dwarf planet from a regular planet?
• Why was Pluto reclassified as a dwarf planet?
• Name at least two other recognized dwarf planets besides Pluto.

Related terms

Pluto:

Once considered the ninth planet in our Solar System but reclassified as a dwarf planet in 2006.

Kuiper Belt:

A region of the Solar System beyond Neptune filled with small icy bodies where many dwarf planets are located.

Charon:

The largest moon of Pluto often considered part of a double dwarf planet system due to its size relative to Pluto.