Of planets and plutons

This has nothing to do with politics or how city government works or fauxtography. I just find this really interesting. Our understanding of the solar system is about to change, and some science textbook publishers are scrambling to keep up.

From the Web site of the International Astronomical Union:

"If the proposed Resolution is passed, the 12 planets in our Solar System will be Mercury, Venus, Earth, Mars, Ceres, Jupiter, Saturn, Uranus, Neptune, Pluto, Charon and 2003 UB313. The name 2003 UB313 is provisional, as a 'real' name has not yet been assigned to this object. (Ross note: Some folks have given this planet the working name of Xena, after the warrior princess of TV fame). A decision and announcement of a new name are likely not to be made during the IAU General Assembly in Prague, but at a later time. The naming procedures depend on the outcome of the Resolution vote. There will most likely be more planets announced by the IAU in the future. Currently a dozen "candidate planets" are listed on IAU's 'watchlist' which keeps changing as new objects are found and the physics of the existing candidates becomes better known.

"The IAU draft Resolution also defines a new category of planet for official use: 'pluton.' Plutons are distinguished from classical planets in that they reside in orbits around the Sun that take longer than 200 years to complete (i.e. they orbit beyond Neptune). Plutons typically have orbits that are highly tilted with respect to the classical planets (technically referred to as a large orbital inclination). Plutons also typically have orbits that are far from being perfectly circular (technically referred to as having a large orbital eccentricity). All of these distinguishing characteristics for plutons are scientifically interesting in that they suggest a different origin from the classical planets.

"The draft 'Planet Definition' Resolution will be discussed and refined during the General Assembly and then it (plus four other Resolutions) will be presented for voting at the 2nd session of the GA 24 August between 14:00 and 17:30 CEST."

They always told me Ceres was an asteroid between Mars and Jupiter. Before the end of this month, it could graduate to planet status. And Pluto stays on the list, with its former moon, Charon, being promoted to planet, which I assume makes Pluto-Charon the only binary planet system in the solar system. And Xena (or whatever its official name will be) will be on there, too.

I love the word "pluton."