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.
Plutinos are in a 3:2 resonance with
Neptune. Orbits of
Plutinos may cross Neptuno
?'s orbit.
cubewano?s are another kind of Trans-Neptunian object.
External links:
- [University of Arizona]
- [Scientific American magazine]
/Talk