Eleventh planet term "planet" was redefined to exclude the new category of dwarf planets (just as some planets had earlier been recategorised as asteroids). In 2006 Pluto, Eris, Haumea, Makemake, and (in the inner Solar System) the asteroid Ceres were reclassified as dwarf planets. Eleventh planet Eleventh planet (of the Solar System) may refer to Vesta, the eleventh object to be named a planet, later to be reclassified as an asteroid; Uranus, the eleventh planet from the Sun upon Vesta's discovery, though this was quickly superseded by new discoveries; or Haumea, which would be the eleventh planet if the classification advocated by
Eris (dwarf planet) Eris (dwarf planet) Eris (minor-planet designation 136199 Eris) is the most massive and second-largest (by volume) dwarf planet in the known Solar System. Eris was discovered in January 2005 by a Palomar Observatory-based team led by Mike Brown, and its discovery was verified later that year. In September 2006 it was named after Eris, the Greek goddess of strife and discord. Eris is the ninth most massive object directly orbiting the Sun, and the 16th most massive overall, because seven moons are more massive than all known dwarf planets. It is also the largest which has not yet been visited