I briefly explained the history of how planets get discovered, and how improving technology has made it easier to find objects in space. They were amazed that anyone could have spotted Pluto from Earth with 1930s telescope technology, or that comparing fuzzy photos could work for detecting the far-off planet....

I discussed the controversy over Pluto's demotion, explaining how the new definition of planet is not accurate, and how less than 5% of the IAU actually voted on the matter. The students had trouble understanding the voting part of it, since they all seem to assume that if something is voted on, it must be fair. So, I presented an example. "Let's say that when your teacher and I went to this school, it was decided that every year the 6th grade class would get to go to the circus. Now, years later, someone decides to take a vote about whether to keep going on the circus trip. Instead of all 50 of you voting, only three of you vote. One votes 'yes', and two vote 'no'. 'No' wins, but it's not exactly a fair vote, is it? That's what happened to Pluto." Eyes lit up, and lot of heads started shaking.

Like some sort of rulers of the universe, state lawmakers are considering restoring little Pluto's planetary status, casting aside the scientific community's 2006 decision downgrading the distant ice ball.

An Illinois Senate committee on Thursday unanimously supported planet Pluto and declaring March 13 "Pluto Day." The idea now moves to the full Senate for a vote.

ffoeg

Michael A. Burstein is president of the Society for the Preservation of Pluto as a Planet, which goes by the acronym SP3. The group of astronomy buffs formed in the spring of 2006, when rumors first started circulating that Pluto was in trouble.

Burstein preferred the IAU's initial idea for a planet definition, which was never voted upon at their solar-system-shattering meeting last August.

By that definition—that a planet should directly orbit a star and be massive enough to be round—Pluto would still be a planet, as would dwarf planets Eris and Ceres, a large, round asteroid orbiting near Jupiter.

It's fine if we end up with 50 or even 100 planets as new objects are discovered, Burstein said. We could keep the math easy by calling the old guard, including Pluto, "classical planets," he added.

For now, Burstein's group is laying low to see what the pros do—under the guidance of New Horizons' Alan Stern. Stern is leading the charge of professional astronomers to dismiss the IAU's ruling.

"People just aren't using the IAU definition because it's so substantially flawed," he said. "Even their own members, and I'm one, aren't using the IAU definition."

The debate over a better definition was a hot topic at the April meeting of the European Geophysical Union. And it's already part of the agenda for the February 2008 meeting of the American Association for the Advancement of Science.

laurele

Pluto’s remarkable history is compelling to so many people perhaps because it is the tale of a little planet that would not die, that would not even “go away.” A friend of mine, upon hearing this fascinating history, reflected a thought that might not be scientific but is nevertheless profound: Pluto was meant to be found. It was meant to join the family of planets...