PRAGUE, Czech Republic (AP) -- Leading astronomers declared Thursday that Pluto is no longer a planet under historic new guidelines that downsize the solar system from nine planets to eight.
After a tumultuous week of clashing over the essence of the cosmos, the International Astronomical Union stripped Pluto of the planetary status it has held since its discovery in 1930. The new definition of what is -- and isn't -- a planet fills a centuries-old black hole for scientists who have labored since Copernicus without one.

Although astronomers applauded after the vote, Jocelyn Bell Burnell -- a specialist in neutron stars from Northern Ireland who oversaw the proceedings -- urged those who might be "quite disappointed" to look on the bright side.

"It could be argued that we are creating an umbrella called 'planet' under which the dwarf planets exist," she said, drawing laughter by waving a stuffed Pluto of Walt Disney fame beneath a real umbrella.

The decision by the prestigious international group spells out the basic tests that celestial objects will have to meet before they can be considered for admission to the elite cosmic club.

For now, membership will be restricted to the eight "classical" planets in the solar system: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.

Much-maligned Pluto doesn't make the grade under the new rules for a planet: "a celestial body that is in orbit around the sun, has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a ... nearly round shape, and has cleared the neighborhood around its orbit."

Pluto is automatically disqualified because its oblong orbit overlaps with Neptune's.

Instead, it will be reclassified in a new category of "dwarf planets," similar to what long have been termed "minor planets." The definition also lays out a third class of lesser objects that orbit the sun -- "small solar system bodies," a term that will apply to numerous asteroids, comets and other natural satellites.

It was unclear how Pluto's demotion might affect the mission of NASA's New Horizons spacecraft, which earlier this year began a 91/2-year journey to the oddball object to unearth more of its secrets.

The decision at a conference of 2,500 astronomers from 75 countries was a dramatic shift from just a week ago, when the group's leaders floated a proposal that would have reaffirmed Pluto's planetary status and made planets of its largest moon and two other objects. (Watch why some think planet size doesn't matter -- 3:39)

That plan proved highly unpopular, splitting astronomers into factions and triggering days of sometimes combative debate that led to Pluto's undoing.

Now, two of the objects that at one point were cruising toward possible full-fledged planethood will join Pluto as dwarfs: the asteroid Ceres, which was a planet in the 1800s before it got demoted, and 2003 UB313, an icy object slightly larger than Pluto whose discoverer, Michael Brown of the California Institute of Technology, has nicknamed "Xena."

Charon, the largest of Pluto's three moons, is no longer under consideration for any special designation.

Brown was pleased by the decision. He had argued that Pluto and similar bodies didn't deserve planet status, saying that would "take the magic out of the solar system."

"UB313 is the largest dwarf planet. That's kind of cool," he said.



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Crazy! So, technically theres 12 "planets" including the two other dwarf planets? Ahh! Insane.

When I was in an astronomy class in college (about 5 years ago), the professor mentioned that this might happen in the near future. Shame though, I always liked referring to it as a planet, even if it didn't fit in with the either two sectors. Oh, well change is change. But I didn't know about Ceres and Xena, very interesting. Thanks for posting!

poor pluto

About time, Neptune rules Pluto drools.

It's of no real consequence to me at all, and yet I feel strangely gutted about that news. Can't put my finger on why.

so do i. i guess i just liked pluto. it's really a major event.

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The make-up of the solar system doesn't really change that often. And yet... it just did. Say hello to Dwarf Planets.

Its still hasn't changed, but things in it have just been reclassified. The fact is this has been a long time coming. When they first discovered pluto they thought it was a planet because they didn't see the 1000's of other objects very similar to it hanging around in the kuiper belt. Astronomers have been putting off the reclassification partly for this reason. (They didn't want to upset the public and go against tradition, etc.) But I guess someone demanded a final answer. :shrugs:

i feel like all that time spent in school trying to memorise the planets -in the correct order- was just a huge waste of time.

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how in the hell do i still have a sub?

pluto was my favorite

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my heart isn't black, it's just dirty from the floors

Well, as a scorpio I guess my governing planet no longer exists?

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You are not who you thought you were. Your personality must immediately change to reflect these developments.

i dont feel like it was a waste of time.. i mean.. you can run around going "MY VERY EARLY MARRIAGE JUST SUUUUUITS UNCLE WHATEVER FINE!!!!" all spaz & itd b more entertaining than running around quoting the order of the books in the bible

eff that! i'm not going with the checker republic!! - well, not their stoopid scientist, anyway, who just wants to mess up the whole of the planets, order, .. so we say pluto ISNT a planet now just because some nutter tells us it is no longer????? GET REAL!!!! we have ALWAYS known pluto as a planet.. and this is just an excuse to fuck up astrology's ruling planets & waste a thousand billion trees, axing our planet therefor destroying humanity's breathing & fresh air.. therfor this scientist is an actual terrorist & there shuld b a new war against him for unnecessary destruction of our environment.. SAVE THE WORLD from this prague mad scientist of evil, sumbody much more serious a threat to humanity ever, than say, The Butcher Of Prague :P
I'd love to hear Courtney's opinions on this.......

Shit. The fortune tellers are always right

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They prefer to be called "vertically challenged"

Ceres is mentioned (and destroyed) in the SNES game Super Metroid. That is all.

Doesn't zodiacking consider our Moon to be a planet though?

You can't just say its a planet and then take it back. Its cheating. Pluto is my favourite

No, Scorpio will still be ruled by Pluto, but instead of being ruled by a planet, you are ruled by a moon.. ? I'm guessing.

edit - "How ironic that Pluto should be dismissed on grounds of size. It was discovered at the same time as Plutonium. Hence the similar name. Pluto governs nuclear energy which is all about the power of subatomic particles. You can hardly say that these are 'too small to matter!' To astronomers, Pluto may now be a 'dwarf planet' but to astrologers, it remains terribly important."
http://cainer.com/

Hahaha that guy's a mentalist.