What is the difference between dwarf planets and other planets is it just size or are there other factors?

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What is the difference between dwarf planets and other planets is it just size or are there other factors?

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[Three rules are used to categorize a planet.](https://en.m.wikipedia.org/wiki/IAU_definition_of_planet)

1). Does it orbit the sun

2). Is it large enough that it has become nearly round over time

3). Has it “cleared the neighborhood” around its orbit.

Planets can say yes to all three, but dwarf planets have not “cleared the neighborhood”

The definition of clearing the neighborhood is a bit tricky to nail down exactly but it essentially means that it’s gravitationally dominant, or that nothing has a strong gravitational force effecting it other than the sun and any of its moons. In Pluto’s case, it crosses Neptune’s orbit, proving that Neptune has some pull on Pluto’s orbit.

The IAU defines a Planet and Dwarf Planet thusly:

A planet is a celestial body that

* (a) is in orbit around the Sun,
* (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and
* (c) has cleared the neighbourhood around its orbit.

A “dwarf planet” is a celestial body that

* (a) is in orbit around the Sun,
* (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape
* (c) has not cleared the neighbourhood around its orbit, and
* (d) is not a satellite.

So interestingly, it is not its mass that makes it a “dwarf” but rather whether it shares its orbit with other objects.