Pluto
A body discovered in 1930 and long classified as the ninth planet of the Solar System, until the International Astronomical Union's 2006 redefinition of "planet" reclassified it as a dwarf planet.
Pluto hasn't completed a full Orbit around the sun since its 1930 discovery. With an orbital period of about 248 years, it will finish its first lap in 2178. Counting from its 2006 demotion as a Solar System Planet, it will complete a full orbit in 2254.
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