Planet X
- Type
- Proposed Planet
- Diameter
- Unknown
- Distance from Sun
- Unknown, but beyond Neptune
- Orbit Time
- Possibly thousands of years
- Length of Day
- Unknown
- Atmosphere
- Unknown
- Temperature
- Unknown, but likely very cold
- Date of Discovery
- Yet to be discovered
- For more than a century the idea of a large planet at the outer edges of the Solar System has given rise to the idea of Planet X, but the search for various locations it might be has turned up nothing.
- What planets have been proposed for Planet X?
- Located in
- Solar System
- Percival Lowell first proposed that slight changes in the orbits of the outer planets might be the result of an undiscovered planet.
- Clyde Tombaugh's discovery of Pluto in 1930 seemed to agree with that until the 1970s when it became very clear Pluto was too small.
- Any Planet X would have to sit beyond Neptune, and at a distance that would mean it takes thousands of years to complete one orbit.
- Some current ideas for Planet X still need confirmation by observation and analysis of calculations.
