Many remember when Pluto, the dwarf planet recognized by its heart-shaped feature, was demoted from its planetary status. On Aug. 24, 2006, the International Astronomical Union voted to downgrade Pluto to a dwarf planet after it was discovered to be much smaller than originally thought, according to History. Now, Aug. 24 is recognized as Pluto Demoted Day. Despite Pluto’s demotion, the state of New Mexico recognizes Pluto’s existence as a planet.
Source: Eighteen years ago, Pluto was demoted — except in New Mexico