Look up Planet Nine or Planet 9 in Wiktionary, the free dictionary.

Ninth planet is a concept related to planets beyond Neptune.

Ninth planet or Planet Nine may also refer to:

Astronomy

  • Neptune, sometimes considered the ninth planet from 1979–1999 when Pluto was classified as a planet and was temporarily closer to the Sun than Neptune
  • Planet Nine, hypothetical ninth planet in the outer Solar System
  • Pluto, considered the ninth planet from its 1930 discovery until it was reclassified as a dwarf planet in 2006 (except 1979–1999, see above)

Music

See also

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