steve wrote:
With this set to be finalised fairly soon in September 2006 I think it
is essential that a few sensible parameters are added.

1) A body in orbit around a star.

2) Size must be larger than Pluto ( or another agreed specified size
and mass) to give a minimum size UNLESS extra-terrestial life is found
on the planet when a much smaller size would be allowed.

3) If the size of a moon is similar (to a stated percentage e.g. 80%)
to the larger body in its group it to can be called a planet if it
meets (1) and (2)
Thus it is possibe to have binary planets.

4) It would probably be necessary to specify a maximum distance from
the star in which the planet is in orbit to dis-allow wandering rocks.

To me it's easy: There are eight planets, Mercury through Neptune.
They are all in circular orbits. They don't cross any other planet's
orbit. They're not part of a group of objects. With the exception of
Mercury, they are larger than any other known objects in the solar
system.

The remainder are asteroids, KBO's, comets, and satelites. The only
remaining object not known to be part of a group is Sedna, and it
probably is part of a yet unknown group.

Consider this: Neptune's moon Triton is believed to be a captured KBO,
and is larger than Pluto. Prior to its capture by Neptune, was Triton
a planet?