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How many dwarf planets are there in our Solar System?

Last Reviewed and Updated on August 1, 2022

Our Solar System has eight full-fledged planets, but there are also quite a few wonderful dwarf planets out there as well. Let’s explore just How many dwarf planets are there in our Solar System and if there could be any more discovered in the future.

What defines a dwarf planet?

First thing first. What defines a planet from a dwarf planet? They share much of the same characteristics, after all.

For a celestial body to be classified as a planet;

  • the body has to have a nearly round shape
  • it has to orbit a star (Sun)
  • has cleared the neighborhood around its orbit
  • has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (to simplify, Earth has such equilibrium; if it wouldn’t, we’d either be losing the atmosphere, or it would collapse into a dense thin layer, for example)

Dwarf planets are astronomical bodies that don’t meet all of the criteria but must still meet a few;

  • they orbit the Sun
  • have enough mass to assume a nearly round shape
  • they aren’t a moon
  • have not cleared the neighborhood around its orbit

Dwarf planets are also smaller than any of the eight classical planets.

Want to learn more? Read our list of facts about dwarf planets

How many dwarf planets are there in our Solar System?

The answer might surprise you, but it depends on who you ask.

Even with all these criteria, there is still no clear definition of what could be a dwarf planet as the line between a planet and dwarf planet or a dwarf planet and an asteroid can be a thin one. So different astronomers and agencies have different numbers.

The number of dwarf planets in our Solar System range from 5 and counting to over 100, depending on the agency or astronomer observing.

Dwarf planets

The international astronomical union (IAU) currently recognizes five dwarf planets, with more being considered (source).

Besides the five dwarf planets, we’re also listing some other dwarf planets or soon-to-be dwarf planets.

1. Ceres (recognized by IAU)

Ceres is a dwarf planet in the asteroid belt between Jupiter and Mars. It was first classified as a planet, then an asteroid, and finally, in 2006, as a dwarf planet. It is the closest one to the Sun.

2. Pluto (recognized by IAU)

Pluto is the most known of all dwarf planets as it was recently classified as the ninth planet in our Solar System. Pluto is partially in the Kuiper belt, a ring of bodies beyond the orbit of Neptune; it is also the largest known dwarf planet.

Read: facts about Pluto

3. Haumea (recognized by IAU)

Haumea is the oddball when it comes to dwarf planets. While most dwarf planets have an almost round shape, Haumea is an oval object.

4. Makemake (recognized by IAU)

Makemake was discovered in 2005 and is one of the largest Kuiper belt objects. It was named after Makemake, a creator god in the Rapa Nui mythology of Easter Island.

5. Eris (recognized by IAU)

Eris is arguably the most important dwarf planet as it was the discovery of this astronomical object that prompted the International Astronomical Union to define the term planet and introduce the term dwarf planet.

It is the most massive one of all known dwarf planets.

Most likely dwarf planets

These are some of the most likely dwarf planets. Some astronomers already consider them as such, but they haven’t yet been officially classified by the IAU.

  • Orcus
  • Quaoar
  • Gonggong
  • Sedna
  • Charon, the moon of Pluto

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