Planet vs. Dwarf Planet: What's the Difference?

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A planet and a dwarf planet both orbit the Sun and are massive enough for gravity to pull them into a nearly round shape, but only a planet has cleared its orbital path of other objects. This rule, set by the International Astronomical Union in 2006, gives the Solar System eight planets and moved Pluto into the dwarf planet category.

At a glance

	Planet	Dwarf Planet
Orbits the Sun	Yes	Yes, and is not a moon of another body
Nearly round shape	Yes, shaped by its own gravity	Yes, shaped by its own gravity
Cleared its orbit	Yes; dominates its orbital zone	No; shares its zone with similar bodies
Number recognised	Eight, from Mercury to Neptune	Five: Ceres, Pluto, Haumea, Makemake, Eris
Typical location	Inner and outer Solar System	Asteroid belt or beyond Neptune

Which should you use?

Planet

Use planet for the eight dominant worlds, such as Earth or Jupiter, which each sweep their orbit clear by pulling in or flinging away smaller bodies.

Dwarf Planet

Use dwarf planet for round bodies that share their region, such as Pluto in the icy Kuiper belt or Ceres in the asteroid belt between Mars and Jupiter.

Frequently asked questions

Why is Pluto no longer a planet?

Pluto orbits within the Kuiper belt, a region crowded with icy bodies, and it has not cleared them away. After Eris, a similarly sized object, was found beyond Neptune, the IAU in 2006 defined planets formally, and Pluto failed the third test.

Is a dwarf planet a type of planet?

Not under the IAU definition. Despite the name, a dwarf planet is a separate category, not a smaller kind of planet. Some planetary scientists disagree and prefer a geology-based definition, so the debate continues, but official usage keeps the two groups distinct.

Is Ceres a dwarf planet or an asteroid?

Ceres is a dwarf planet. It is the largest object in the asteroid belt and is massive enough to be rounded by its own gravity, but it shares its orbit with countless asteroids, so it meets the dwarf planet rules.