Group 9 Dwarf Planets

Dwarf planet is a new class of astronomical objects. It was created in 2006 by the International Astronomical Union as part of their struggle to define the word 'planet'. The discovery of objects in the outer solar system which were larger than or of similar size as Pluto necessitated the need for a definition. (This distant region is called the Kuiper Belt and extends far beyond the orbit of Neptune.) After much debate, it was decided that to be a planet in our solar system, an object must be in orbit around the Sun, have enough mass so that it has become round in shape due to its own gravity, and have cleared out its orbital path around the Sun (so there are not similar objects to itself at roughly the same distance from the Sun). Dwarf planets were declared to be the class of objects which met the first 2 requirements, but failed the third. It was then made clear that planets and dwarf planets are distinct classes of objects. Dwarf planets are not planets.


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