In August 2006, members of the International Astronomical Union approved a new definition of the word planet -- a definition that kicked Pluto out of the planetary club for the first time since its discovery in 1930.

That decision has inspired a backlash from both astronomers and the general public. Some astronomers are angry that only about 400 of their colleagues -- just the few people remaining on the last day of a weeklong IAU conference in Prague -- voted on the new definition, and they question its scientific validity.

Alan Stern, the head of NASA's New Horizons mission to Pluto, has circulated a petition asking IAU to reconsider the decision, and news outlets from The New York Times to the BBC have covered the controversy.

In some quarters, though, the debate has had a different kind of backlash -- those unhappy with the amount of attention Pluto's reclassification to "dwarf" planet received.

"I think the debate trivializes astrophysics," said astronomer James Sweitzer of the University of Chicago. "Very few researchers are interested in the subject at all."

The semantic debate over whether or not to call Pluto a planet is overshadowing other, more vital research in astronomy, Sweitzer and others say -- and giving the public a skewed view of what modern astronomy is all about.

Nowadays, Sweitzer said, the planets of our solar system, be they eight or nine, make up only a tiny fraction of what astronomers study. The observable universe stretches to a distance trillions of times the distance between the Earth and Pluto.

"The size of a human hair is to the size of Pluto's orbit what the size of Pluto's orbit is to the horizon of our universe," he said. "So, in the scheme of things, the problem of Pluto is as significant as that of one hair on the head of an astronomer."

Too many educators, from elementary teachers on up, stick to a "planetary coloring book" model of teaching astronomy, he said, teaching astronomy by listing the components of our solar system. 

The Pluto debate even limits our understanding of planets, according to Sweitzer. In the past 15 years, astronomers have identified more than 200 planets orbiting other stars.

"I often imagine a kid going to a planetarium today as opposed to 50 years ago," he said, "and when she gets home and her grandpa asks her 'what's your favorite planet?', she says, 'Which solar system?'"

Jay Pasachoff, an astronomer at Williams College, is one of those researchers who does focus his research on our solar system -- the outer planets and solar eclipses are among his specialties.

Still, he too thinks that the Pluto debate is garnering more attention than it deserves.

"A couple of days before we got to Prague, I read a very misleading news article that said that 3,000 astronomers were gathering to debate the status of Pluto. Whereas really, the status of Pluto was a very minor part of this meeting," Pasachoff said.

He said that he personally would be inclined to keep Pluto a planet, simply to honor its history as one. But he added, the issue is not high on his -- or many of his colleagues' -- priority list.

In fact, according to Pasachoff, at an October 2006 meeting of the American Astronomical Society's division of planetary sciences -- whose members one might expect to be keenly interested in the Pluto debate -- astronomers discussed new observations of Pluto's atmosphere, among other recent research findings. There was no official discussion, however, of its planetary status.

-- By Lea Winerman, Online NewsHour