Under the new proposal being considered by the IAU, our solar system will include nine twelve planets, and that’s probably just the beginning. Credit: International Astronomical Union/Martin Kornmesser

I’m sure by now you’ve caught wind of the long-awaited news:

The world’s astronomers, under the auspices of the International Astronomical Union (IAU), have concluded two years of work defining the difference between “planets” and the smaller “solar system bodies” such as comets and asteroids. If the definition is approved by the astronomers gathered 14-25 August 2006 at the IAU General Assembly in Prague, our Solar System will include 12 planets, with more to come: eight classical planets that dominate the system, three planets in a new and growing category of “plutons” - Pluto-like objects - and Ceres. Pluto remains a planet and is the prototype for the new category of “plutons.”

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. 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.

So, after many months of deliberation, we’ve been offered some new planetary guidelines. Are they workable? Are the tweaks made going to create more problems than they’d solve? I’m not sure exactly how I feel about this proposal just yet. Not like it matters, anyway, as I’m just another average photon thief wielding a lightbucket…

Personally, I have no problem with Pluto being referred to as a planet. I also wouldn’t mind if it received a demotion of any sort. Call it a Kuiper Belt Object, Dwarf Planet, trans-Neptunian Object… call it a planet with an asterisk; in the end, it doesn’t really matter. It doesn’t change Pluto’s characteristics or what ongoing study of the Plutonian system can help us understand about the more distant reaches of our solar system. Shuffling the nomenclature doesn’t change the fact that we have a great deal to learn about it. Regardless of the label it’s assigned, even under optimal conditions, it’ll appear as no more than a dim, lonely speck through my telescope.

This ongoing wrangling over nomenclature has irked me. Since last year’s news of the discovery made by Mike Brown and his colleagues of 2003 UB313 - an object similar in size to Pluto but at orbiting at a staggering distance of 15 billion kilometers from the Sun - it seems to me that the majority of public discussion has centered on the least important aspects. Will “Xena” be called a planet? What will its real name be? What about “Gabrielle?” Will Pluto still be called a planet? When will they decide?…

Such questions, to me anyway, seem terribly misguided. They’re equally as trivial as gossiping over who got cut from the latest round of American Idol, or which celebrity wore what dress to the Oscars. What do the objects’ physical properties suggest about the Kuiper Belt? What secrets can they reveal about our solar system’s distant neighbors? What ramifications do these discoveries have upon our ideas of solar system formation and evolution? Scores of more pressing questions should arise from the present scenario, yet for many it’s relegated to a strange cosmic popularity contest. That reflects negatively upon both our popular culture and our sense of priorities. I don’t think the lackluster science reporting in the mainstream media helps the situation, either. But I digress.

Come August 24th, we’ll know if bundles of textbooks will require revision to reflect this new picture of our solar system. In the interim, and for some time thereafter, the debates will rage on. To get a better indication of how the pros view the IAU’s proposal, surf on to the following:

Congratulations! It’s a planet! - Phil Plait

The Cash Value of Astronomical Ideas - Sean Carroll

The IAU proposal on the definition of “planet” - Mike Brown

What’s a Planet? - Richard Fienberg

Nine Planets Become 12 with Controversial New Definition - Robert Roy Britt