[X] My Assistant

[Planet X]

First off, I think the new IAU planet definition is poorly worded, with too many loop holes.
This brings me to an important concept. If the term "Minor Planet" has officially been ditched as a reference to small bodies, I'd suggest that they revive the term to refer to bodies in the 2000-6000 km diameter range.

With that being said, I think it's time to spell out my own personal definitions of the various types of bodies in our solar system. Listed below are my classifications and what they mean, sort of based on the IAU definitions and sort of not.

1. Major Planet - a celestial body that: (a) is above 6000 km in diameter, ( directly orbits the Sun and not another body, © has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, (d) has sufficient mass to both have a differentiated interior and retain an atmosphere in a vacuum and finally, (e) has definitely cleared the neighborhood around its orbit (with the legitimate exception of Trojan Bodies).

2. Minor Planet - a celestial body that: (a) is 2000-6000 km in diameter, ( directly orbits the Sun and not another body, © has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, (d) has sufficient mass to both have a differentiated interior and retain an atmosphere in a vacuum, but (e) may or may not have cleared the neighborhood around its orbit (with the legitimate exception of Trojan Bodies).

3. Planetoid - a celestial dwarf body that: (a) directly orbits the Sun, ( has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, © has insufficient mass to have a differentiated interior or retain an atmosphere in a vacuum, (d) has not cleared the neighborhood around its orbit, and (e) is not a satellite of another body.

(4) Planetesimal - a celestial dwarf body that: (a) directly orbits the sun, ( has insufficient mass for its self-gravity to overcome rigid body forces so that it assumes a basically potato-like (irregular) shape, © has insufficient mass to have a differentiated interior or retain an atmosphere in a vacuum, (d) has not cleared the neighborhood around its orbit, and (e) is not a satellite of another body.

That's my take on the matter. I think this would be a good starting point to fine tune the new IAU planet definition. In this scheme, we would have 10 principal bodies orbiting the sun: 7 major and 3 minor planets. I also think the public would accept a scheme like this, as it would allow Pluto and Eris to be planets, yet not force the classification of planet to a million round bodies below 2000 km in diameter. Plus, as Mike Brown even said after discovering Eris, it would give future generations the possibility of actually finding a new planet. Besides, it's highly unlikely the number of bodies above 2000 km in diameter will skyrocket to ridiculous numbers anytime soon, even out to several hundred AU distant.

So, what are your thoughts on this matter? Later!

J P