Trans-Neptunian object

Trans-Neptunian objects (TNOs) are any objects in the solar system that have an orbit beyond Neptune. The Kuiper Belt and Oort cloud are names for some subdivisions of that volume of space. Pluto is a trans-Neptunian object, and if discovered at this time would not be called a planet. Another of the named Trans-Neptunian Objects is Varuna. In July 2001 a new object "2001 KX76" half the size of Pluto was discovered.

Gravity, the attracting force between all matter, also attracts planets. Due to the changes in the orbits of the known planets in the early 1900s, it was assumed that there was one or more planets beyond Neptune, but not yet identified. Pluto was the first of these to be identified, but in recent years, a significant number of small planetoids have been discovered.

Current speculation in the astronomical community due to the gravitational disturbances of the planets suggest that there may be a larger planet, or even a [brown dwarf]? circling the Sun at a very large distance.

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Plutinos are in a 3:2 resonance with Neptune. Orbits of Plutinos may cross Neptuno?'s orbit.

cubewano?s are anhoter kind of Trans-Neptunian objects

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External links:

[University of Arizona]

[Scientific American magazine]

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