Pluto's Planetary Status Teeters -- Again In a stunning reversal of fortune, it now seems likely that Pluto will lose its title of planet. Scientists meeting in Prague were presented with a new definition of the word "planet" last week, which would have included Pluto as a planet. But the proposal met with fierce protests. Opponents say there are hundreds of objects like Pluto.
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Pluto's Planetary Status Teeters -- Again

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Pluto's Planetary Status Teeters -- Again

Pluto's Planetary Status Teeters -- Again

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From NPR News, this is ALL THINGS CONSIDERED. I'm Robert Siegel.


And I'm Melissa Block.

There is some bad news for Pluto today. An international group of astronomers has torn up a proposal that would have kept it a planet. They have written a new resolution to be voted on this Thursday. It would leave our solar system with just eight planets, Pluto not among them.

NPR's David Kestenbaum reports.


Pluto's fate is being decided in hotel bars and convention rooms in Prague, where scientists with the International Astronomical Union are meeting. Astronomers say the gatherings are sober, sometimes dull affairs. Not when you mess with Pluto.

Before this meeting, the IAU convened a secret panel to come up with an official definition of the word planet. It was unveiled last week and it would've counted anything in essence that was round and principally orbited the sun. That meant Pluto and possibly dozens of other small objects were in. Owen Gingrich at Harvard University chaired the committee that came up with the proposal, and he said it did not go over as he had hoped this week.

Mr. OWEN GINGRICH (Harvard University): It was a very noisy, cacophonous meeting. Just a little bit more difficult than herding cats. I suppose it would be like herding tigers.

KESTENBAUM: The fiercest growls came from orbital dynamicists who argued that Pluto and the other things were just too small. They said a planet should be something that is the dominant object orbiting in its zone. Pluto would not count since it's part of what astronomers call the Kuiper Belt, a region beyond Neptune with scores of small, icy objects. Gingrich says the definition sounds a little vague to him, but the critics won the day.

Mr. GINGRICH: According to the resolution, which is most likely to be passed this Thursday, the planets will be defined as the eight classical planets from Mercury to Neptune and Pluto will no longer be considered a planet in that category.

KESTENBAUM: There will be several reactions to this. One, who cares? There are probably a number of astronomers in that category. Two, you can't demote Pluto. And, three.

Mr. RICHARD HENRY (Johns Hopkins University): Oh, that's great news.

KESTENBAUM: Richard Henry is an astronomer at Johns Hopkins University. His department took an informal poll. Most faculty wanted to keep Pluto, but Henry wrote, down with Pluto. Imagine, he says, we were born in a distant solar system and came to visit this one. We'd easily pick out eight planets.

Mr. HENRY: And there's a whole bunch of comments, of course, and there's loads and loads of little objects in the outer part of the system. And then do you know what happens? We let on this expedition a dimwit who says, let's pick one of those little objects in the outer solar system and call it a planet too. It just shows up how arbitrary the whole thing is. It's an historical artifact. It has nothing to do with reality.

KESTENBAUM: The resolution to be voted on may include a concession to preserve Pluto's dignity. Pluto could be not an actual planet but a special dwarf planet thing of some sort. Pluton was the word used in the original plan for Pluto and its friends. Owen Gingrich says that too came under assault.

Mr. GINGRICH: The geologists launched a tremendous campaign against us saying that Pluton was their word for an intrusion of magna. And at the same time, the Italians pointed out that Pluton was the word for Pluto in Italian and so that wouldn't work.

KESTENBAUM: He says the term Plutonian is now being considered. If the proposal to throw Pluto out passes, the ripples could be far reaching. Solar system models in schools might have to change, and the phone number of the Planetary Society, a space interest group. Louis Freedman runs it.

And what is the phone number you have?

Mr. LOUIS FREEDMAN (Planetary Society): 800-9-WORLDS.

KESTENBAUM: And what are you going to do about that?

Mr. FREEDMAN: Well, I guess we - maybe I should - in fact, I think I'll do that. You have motivated me. I am going to now call the phone company and see if I can get a change of our phone number.

KESTENBAUM: There's also the matter of Walt Disney's cartoon Pluto. Some astronomers suspect that's one reason people care so much about this in the first place. Say Pluto and people think about Mickey Mouse's dog.

David Kestenbaum, NPR News.

BLOCK: If you're inclined to learn more about the planet Pluto, you can go to You'll find more on the debate over its status and you can find out how scientist Percival Lowell's Mars Mania led to the discovery of Pluto.

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