On Aug. 24, 2006, the International Astronomical Union (IAU) decided that Pluto wasn’t a planet anymore. Instead, Pluto is now officially classified as a dwarf planet along with four other confirmed dwarf planets in the outskirts of the solar system.
Related: Photos of Pluto and Its Moons
This decision sparked outrage around the world, and the controversy is still very much alive today. Astronomers in favor of Pluto’s demotion argued that a planet by definition should have cleared its orbit around the sun.
Pluto and the more distant dwarf planets fail to meet this criterion. If Pluto were to keep its planetary status, those dwarf planets would also need to be classified planets. While astronomers continue to debate this new definition, the public has come together to defend Pluto’s title.
For now, Pluto will just have to be the king of the dwarf planets. And that’s pretty cool, too.
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