Wednesday, June 11, 2008

Plutoids??? What Was the IAU Thinking???

Just when one thinks the IAU has done the extent of its damage in the planet debate and that things cannot get any worse, they do exactly that. With no advance notice to anyone but its Executive Committee, the IAU today announced that dwarf planets beyond the orbit of Neptune are henceforth to be called "plutoids."

And this is supposed to be a "bone" thrown to supporters of Pluto's planet status. Not quite.

After the resolution labeling dwarf planets beyond Neptune "Plutonian objects" failed at the IAU General Assemby in 2006 (that's the vote on the last day of the two week conference, by four percent of its members), the IAU Committee on Small Body Nomenclature and the IAU Working Group for Planetary System Nomenclature set out to come up with a new term to define these objects.

After two years, all they can come up with is "plutoids?" And since Ceres does not orbit beyond Neptune, the IAU is now considering labeling it the lone "ceroid." Are you confused yet?

On one of many television programs covering the US presidential election, a commentator noted wisely that when one makes a mistake, the best thing is to admit to that mistake rather than to further compound it with additional spin and attempts at rationalization.

It's too bad the IAU cannot follow that advice. If it did, its members would admit they messed up in 2006 with the sloppy definition that states that a dwarf planet is not a planet at all and rescind the decision or at least put it to a General Assembly vote that made provisions for electronic voting.

Instead, they chose to further muddy the waters with a new definition that only further confounds the issue.

According to this new definition, no object beyond the orbit of Neptune, regardless of its size, can ever be considered a planet. What kind of science is that? What about the geophysical makeup of these objects? Does that count for nothing? The best way to remedy this is to overturn the decision that dwarf planets are not planets at all. Then we can say that Ceres is an asteroid belt dwarf planet, and Pluto, Eris, and other round KBOs are Kuiper Belt dwarf planets. That keeps things simple; it preserves the identifying feature for planets as being in hydrostatic equilibrium while recognizing the dynamics of these objects by noting they do not dominate the neighborhood of their orbits.

How many IAU members voted on this definition? Certainly far fewer than the 424 who voted for the initial demotion. Just because the IAU claims its processes are democratic does not make them so. Why were major planetary astronomers like Dr. Alan Stern, Dr. Mike Brown (co-discoverer of Eris), and Dr. Hal Weaver not even informed that this discussion was taking place?

IAU General Secretary Karel A. van der Hucht argues that the IAU is open to comments and criticism. But how can anyone comment or criticize when no one even knew this subject was up for discussion?

This was purely and simply a backroom deal, a political decision, not a scientific one. It was made behind closed doors with no attempts at peer review, as is normally done in science. Weaver rightly terms the process used by the IAU here as "archaic" and not befitting an age of transparency.

And Stern is correct in describing the decision as "irrelevant" since it is unlikely to be used by many scientists or lay people because it does nothing more than further the confusion. Additionally, it does not take into account any definition for similar objects found in other solar systems.

This decision does nothing to promote the IAU's International Year of Astronomy, an outreach effort aimed at generating public interest in astronomy; in fact, it does the very opposite by showing the IAU to be an elitist, closed organization out of touch with the public and even with professional astronomers.

I plan to be at the JPL conference in Laurel, Maryland, arguing for the most sane planet definition I have ever heard, courtesy of my astronomy instructor Al Witzgall. Specifically, he says, "a planet is a non-self luminous spheroidal object orbiting a star." That's it. Then we subdivide into terrestrial planets, gas giants, ice giants, ice dwarfs, and perhaps additional categories as more discoveries are made.

A key factor the IAU, with all its PhDs, has yet to learn, is that the process by which something is done is just as important as that action itself. And the process by which they came to the word "plutoid," like the 2006 General Assembly vote, is irreparably flawed.

If Stern follows through on his suggestion to found a rival professional astronomical organization, more power to him.

There is a silver lining here for supporters of Pluto's planethood. Several astronomers, such as Stephen J. Kortenkamp, senior scientist at the Planetary Science Institute in Tucson, Arizona, and astronomy enthusiasts like Michael Burstein of the Society for the Preservation of Pluto as a Planet, have suggested that this weak, tenuous definition will only strengthen the voices of those of us who want to see Pluto's planethood reinstated.

If that does happen, then maybe this farce of a decision will have led to some good.

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