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Dwarf Planets are a category of planets created on 24 August, 2006 in Prague by the International Astronomical Union. The vote and results that led to the creation of the categorisation are much argued about.
What is a Dwarf Planet?
A dwarf planet is defined as an object that orbits the sun, has sufficient self-gravity to obtain a round shape, has not 'cleared the neighbourhood' around its orbit, and is not a satellite of another planet, dwarf planet, or other non-stellar body.
Planets And Dwarf Planets Compared
Most of the requirements for the two are the same. The major difference is that a planet has 'cleared the neighbourhood', while a dwarf planet has not. 'Clearing the neighbourhood' means that nearby asteroids are pulled into an orbit around the planet as a moon.
Why Do We Have Dwarf Planets?
For many years, it was debated whether Pluto was an actual planet or not. People argued that if Pluto was a planet, so were the asteroid Ceres, Pluto's moon Charon, and 2003 UB313, an object orbiting the sun beyond Pluto. 2003 UB313's codename used to be Xena (as in the American fantasy TV series Xena: Warrior Princess), until it was given the official name Eris after the Greek goddess of discord.
After much debating, scientists decided to create a new category rather then have schoolchildren learn the name of three extra planets, but a good number of astronomers don't like the new classification, calling it 'embarrassing' and 'inconsistent'.
Which Bodies are Dwarf Planets?
Along with Pluto, both Ceres and Eris are classified as dwarf planets. Charon is now classified as a 'small solar system body'. There are other bodies that astronomers are considering as potential dwarf planets. Some sources claim that there are up to 45 such bodies. The following is a short list of potential dwarf planets.
- 2005 FY9 ('Easterbunny')
- 2003 EL61('Santa')
- 2002 TC302
- 2002 UX25
- 2002 TX300
- 2002 AW197
At the time of writing, it is still unknown whether Vesta, Pallas and Hygeia fit the aforementioned requirements of having a hydrostatic equilibrium, that is, sufficient gravitation to act like a fluid and assume a nearly round shape.