Planet X (disambiguation)

Look up Planet X in Wiktionary, the free dictionary.

Planet X is a hypothetical ninth planet of the solar system - specifically a planet beyond the orbit of Neptune. Once believed to be responsible for apparent discrepancies in the orbit of Neptune, the term now refers to any hypothetical planet far enough from the orbit of Neptune as to be undetectable by its gravitational effects on the Kuiper belt.

Planet X may also refer to:

Science fiction

Music

Other uses

See also