Statistics:
* This guess comes from Kepler's Third Law; that is, planets that orbit further away from the Sun will take a longer period of time to complete one orbit.
- Planet Size: ???
- Planetary Mass: ???
- Average Distance from Sun: greater than Pluto, >39.5 AU
- Length of Day: ???
- Length of Year: longer than Pluto's year, > 248.5 Earth Years*
- Atmosphere: ???
- Day/Night Surface Temperature: likely to be extremely cold like Pluto
It has been speculated in the past that there could exist a tenth planet
beyond Pluto.
This mythical world is known as "Planet X" where the X stands for the Roman
numeral ten. Clyde
Tombaugh, the discoverer of Pluto, continued his search for
another planet beyond Pluto but to no avail. No other optical searches
of the heavens beyond Pluto have yielded any evidence for a tenth planetary
body. However, the infrared satellite IRAS has recorded the presence
of thousands of smaller objects by receiving their infrared radiation;
Whether or not any of these objects is an actual planet is still a mystery.
In addition, the Pioneer 10 space probe has by now moved beyond the planetary
limits of the solar system; Pioneer 10's trajectory has shown no known
deviations due to the gravitational interaction of a tenth planet.
Thus, astronomers think that if a tenth planet exists, then it has an extremely
small mass.
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