News Elsewhere

Astronomy group strokes poor Pluto's bruised ego

By Tom Beal

ARIZONA DAILY STAR

Tucson, Arizona | Published: 06.12.2008

The same group that demoted Pluto from planet to dwarf two years ago has decided to honor it by giving its name to potentially thousands of similar objects at the edge of our solar system.

The International Astronomical Union (IAU), the worldwide body in charge of naming things in the sky, chose "plutoid" Wednesday as the new name for some of the objects that it classified two years ago as "dwarf planets."

Only those dwarfs past the orbit of Neptune with a certain brightness qualify for the moniker. Right now that means only Pluto and Eris, but astronomers say many more await discovery.

Tucson astronomer David Levy, friend and biographer of Pluto discoverer Clyde Tom-baugh, said he was "not wild" about the new nomenclature.

"It sounds more like an illness than a name," he said.

Lowell Observatory astronomer Edward Bowell said he has heard plenty of rude comments about plutoids. "It's a very similar medical condition to asteroids," he joked.

Bowell is president of the planetary-systems division of the IAU, the group that recommended the name "plutoid" to the executive committee, which approved it at a meeting in Oslo, Norway, last week, said Bowell.

The group briefly considered "pluton" but dropped that term because geologists had already claimed it to describe a geological feature.

You might remember the furor that arose when the IAU decided two years ago to demote Pluto from planet to dwarf after discoveries of other Pluto-like objects made it incumbent to either expand the list of planets or reconsider the definition.

It hit hard in Arizona, especially at Lowell Observatory in Flagstaff, which had previously boasted of being the only spot in the United States from which a planet had been discovered. Tombaugh discovered Pluto from there in 1930.

The Lowell folks seem to still have trouble talking about it. "Officially we have no comment," said Lowell spokesman Steele Wotkyns, who emphasized that Bowell was speaking on behalf of the IAU and not the observatory.

Bowell said he is reconciled to Pluto's demotion but is not certain the new label will mollify his colleagues at Lowell.

"I was actually against demoting Pluto when I went to the general assembly in Prague where all the fireworks occurred," he said.

Bowell had argued in 2006 for adding planets rather than subtracting them, but has since come to realize that might have led to "a cumbersome list of perhaps 1,000 objects."

At the moment, there is only one official plutoid besides Pluto itself.

CalTech astronomer Mike Brown's discovery of the Pluto-like object now named Eris and now called a plutoid helped set off the planetary debate in 2005.

Brown had nicknamed the object Xena, but after the Pluto furor he submitted it to the IAU for naming as Eris — the mythological Greek goddess of discord and confusion.

Brown was on vacation Wednesday, and his voice mail referred questions about plutoids to his Web site, where he noted that Pluto, Eris and two of his other discoveries are the only objects that currently qualify as plutoids.

Bowell said Brown's other two discoveries will almost certainly earn their plutoid labels, as will many others yet to be found.

Levy said the continuing attempt to clarify Pluto's status "reminds me that this is not a final thing. It's a process."

"I think eventually there will be multiple definitions," he said.

Brown wrote that most astronomers have gotten over the Pluto debate.

"If Pluto is happy being a plutoid, then it is probably OK with the rest of us," he wrote.

● Contact reporter Tom Beal at 573-4158 or tbeal@azstarnet.com.

6 Comments on this story