Slashdot Log In
IAU Demotes Pluto to 'Dwarf Planet' Status
Posted by
timothy
on Thu Aug 24, 2006 09:38 AM
from the and-then-there-were-eight dept.
from the and-then-there-were-eight dept.
davidwr writes "It's official. Pluto's been demoted. It's now one of several 'dwarf planets.' I guess we can drop the 'Period' from 'Mary's violet eyes make John stay up nights.'" (Of course, no one says you have to privately agree with the International Astronomical Union.) Several readers have contributed links to the BBC's coverage of the downgrade, as well as the usefully illustrated story at MSNBC.
Related Stories
[+]
IAU Rules Pluto Still a Planet 244 comments
scottyscout writes "NPR reports that Pluto has dodged a bullet.
An international panel has unanimously recommended that Pluto retain its title as a planet,
and it may be joined by other undersized objects that revolve around the sun.
Some astronomers had lobbied for reclassifying Pluto as its so tiny. And at least one major
museum has excluded Pluto from its planetary display. But sources tell NPR that under the
proposal, to be presented at a big meeting of astronomers in Prague next week for a vote,
Pluto would become part of a new class of small planets and several more objects could be
granted membership."
[+]
IAU Proposes 3 New Planets 316 comments
IZ Reloaded writes "Sources tell SPACE.com that the International Astronomical Union is preparing to include three new entries to the current list of planets in our solar system. From the article: The asteroid Ceres, which is round, would be recast as a dwarf planet in the new scheme. Pluto would remain a planet and its moon Charon would be reclassified as a planet. Both would be called "plutons," however, to distinguish them from the eight "classical" planets. A far-out Pluto-sized object known as 2003 UB313 would also be called a pluton."
[+]
Pluto Decision Meets with Frustration 464 comments
fuzzybunny writes "The BBC reports that the IAU's controversial Prague vote on demoting Pluto from planet status was irregular. 'There were 2,700 astronomers in Prague during that 10-day period. But only 10% of them voted this afternoon.'" On a less serious note, lx writes "Nonplussed by Pluto's recent downgrade from Planet Status, Fox News's own John Gibson does an incredible Stephen Colbert impersonation to correct the 'revisionist history' of the IAU's decision. Exemplifying 'truthiness,' from the article: 'Long ago I learned it was a planet and I see no reason to unlearn it. Why should I?' "
[+]
Pluto Making a Comeback 439 comments
anthemaniac writes "Space.com reports that the American Astronomical Unions Division of Planetary Scientists recognizes the IAU's authority to make a new planet defintion but expects it to be altered. Separately, 300 astronomers have signed a petition saying they won't use the definition. All this stems from the discontent over how only 424 astronomers voted on the proposal that demoted Pluto. Looks like this little dog is on the comeback trail."
[+]
"Xena" To Be Named Eris 167 comments
rdwald writes, "After over a year of hanging in maybe-planet limbo, newly-classified 2003 UB313, nicknamed Xena, now has a permanent name: Eris, goddess of strife. Its moon will be named Dysnomia, after the goddess of lawlessness — in Greek mythology, Eris's daughter — certainly not a reference there... I don't think I'm alone when I say, 'Hail Eris! All hail Discordia!'"
In the same IAU announcement (PDF), Pluto was given its official minor planet number: 134340.
[+]
Why the Word 'Planet' Will Never Be Defined 141 comments
eldavojohn writes "What makes a planet a planet? Slashdot covered the great debate about whether or not Pluto qualified and Space.com now has up an article explaining why we'll never have the term 'planet' defined to a point that everyone can agree on. Divisions in the scientific community currently stand over whether or not it has to be in orbit around a star, the dynamics of the body in question and apparently the country you come from plays a part in it too. Some feel the United States is the dominant deciding factor on the definition but the IAU has not turned to democratizing the definition yet." From the article: "In the broadest terms, a planet could be thought of as anything from an 800-kilometer-wide (500-mile-wide) round rock orbiting a dead star to a colossal gas ball floating alone in space."
[+]
Odd Planet Confuses Scientists 142 comments
eldavojohn writes "While there's been a lot of debate about what is a planet, there is a recent discovery that has scientists even more confused. COROT (COnvection ROtation and planetary Transits) spotted an object that appears to be the size of Jupiter yet is 21.6 times more massive ... and orbits its star in a mere four days and six hours. Now, the other piece of the puzzle is that the star it orbits is more massive and only slightly larger than our Sun. But they can't describe this thing orbiting it. So far they think it is more likely to be a 'failed star' but have settled with 'member of a new-found family of very massive planets that encircle stars more massive than the sun' to describe it accurately."
This discussion has been archived.
No new comments can be posted.
The Fine Print: The following comments are owned by whoever posted them. We are not responsible for them in any way.
Full
Abbreviated
Hidden
Loading... please wait.
my take on it: (Score:5, Funny)
Re: (Score:3, Funny)
Re:my take on it: (Score:5, Funny)
Parent
Re:my take on it: (Score:5, Informative)
I wouldn't call it a screw-up.
The draft proposal was:
Pluto would continue to be a planet, and Ceres, Charon and 2003 UB313 would become planets. However, this criterium is reached by hundreds, even thousands of other celestial bodies in our solar system. Under that proposal, all could gain planet status.
The final text is:
This definition does not define the terms "nearly round", nor "neighbourhood". But having a definition, rather than just an enumeration, is in my opinion a big leap forward. Demoting Pluto is a small price to pay.
I quite like the additional criterion of dominance of a body in its neighbourhood. It's not as arbitrary as simply requiring a minimum mass or size.
On the other hand, I do not like the fact that a planet should orbit to Sun to be called a planet. On this point, I preferred the original proposal in orbit around a star. I don't see why our solar system should be any different, why planet-like celestial bodies orbitting other stars are not called planets.
Parent
Re:my take on it: (Score:5, Interesting)
Pluto orbits the sun, but it also orbits a point in space above its surface. Charon doesn't orbit Pluto, but orbits a point in space above the surface of Pluto, while it too orbits the sun. Can someone explain to me why this shouldn't be called a double?
Parent
Re:my take on it: (Score:4, Interesting)
"is not a satellite" does not exclude Charon, because they picked a somewhat peculiar definition of "satelite" (barycenter of gravity inside the primary), which excludes almost everything we typically think of as a moon, but not Charon. This definition makes the Moon a satelite, but if the Earth had a slightly smaller radius but the same mass, the Moon would follow exactly the same orbital track, but suddenly be a planet.
I beleive they picked this definition of "satellite" specifically to exclude Earths Moon. If you actually plot the orbital tracks of the Moon, Charon, and any other moons you like, one stands out like a sore thumb as the one that should obviously be said to be orbiting the Sun. It's not Charon.
Parent
Re: (Score:3, Interesting)
They claimed to exclude Charon from being a dwarf planet, so they're obviously not using the barycenter definition to determine what a satellite is.
Re: (Score:3, Insightful)
Not that it really matters all that much. As other astronomers have commented, they mostly just say "body" and give a list of specs. Terms like "planet" are a bit too vague to be useful as technical terms. After all, Mercury
Re: (Score:3, Insightful)
.. but given enough time... (Score:3, Insightful)
But isn't the Moon's distance from Earth slowly increasing thus, surely, the binary planet definition will also apply to the Earth+Moon eventually?
Re:.. but given enough time... (Score:4, Informative)
Actually (if I did the math correctly) in about 3,529,037,195 years. That's still within the projected lifetime of the solar system, so yes
Parent
Re: (Score:3, Insightful)
Legal issues.
If we get off this rock, we will probably allow asteroid mining. It would then be OK to reduce an asteroid to rubble to extract the ore that you want. Now imagine Pluto has some valuable Ultra-rareium at its core. Is it OK for a company or a country to smash it to pieces?
These definitions are important so laws can be made. Is it OK to bury radioactive waste in an asteroid? What about Mars? Does this apply to all planets, or
Re: (Score:3, Informative)
> Sun to be called a planet. On this point, I preferred the original
> proposal in orbit around a star. I don't see why our solar system
> should be any different, why planet-like celestial bodies orbitting
> other stars are not called planets.
Because they're only defining what a Solar planet is, not the general meaning of the word "planet":
The IAU therefore resolves that planets
Mutually exclusive (Score:3, Funny)
Sorry, I should have said mutually exclusive set. Really wikipedia has a good diagram, but the orderly diagram makes it appear to be a logical distinction rather the linguistic mess that it is.
A: Pluto is a planet
B: No, Pluto is a dwarf Planet.
A: Yes, that's right I said it was a planet.
B: But it is a dwarf planet, so you are wrong.
A: Isn't a dwarf planet just a type of planet?
B: No.
A: Then why is it called a planet at all
B: uhhh, cause
Re:my take on it: (Score:5, Funny)
What's he going to do now?
Parent
Re: (Score:3, Insightful)
I agree...screw Neptune.
Re: (Score:3, Funny)
Re:my take on it: (Score:5, Funny)
At a rate of once every six days, nine hours, seventeen minutes, and thirty six seconds.
Parent
Re: (Score:3, Insightful)
Clyde Tombaugh is surely spinning!
In astronomy, they don't call it spinning, but "ro...tat...ing" (making finger quotes as I type). You have to give some respect to the man who discovered the biggest snowball that side of the asteroid belt
Mnemonic device update (Score:5, Funny)
Now every geek's question is... (Score:5, Funny)
Re:Now every geek's question is... (Score:5, Funny)
Parent
Astrologers panic! (Score:5, Insightful)
So will this render all astrological predictions which took Pluto into account as invalid? I'm sure the kooks will come up with some excuse to explain how their previous charts were accurate at seeing the future as if they ~knew~ this all along.
Re:Astrologers panic! (Score:5, Insightful)
Parent
Re: (Score:3, Informative)
Then again, when you're dealing with flimflam you can pretty much say whatever you want.
The fact that NPR had this segment only served to legitimize this nonsense and continued to give hope to the gullible that astrology is valid.
A new one (Score:5, Funny)
Why is this "breaking news" (Score:4, Insightful)
Now that would be breaking news!
Re:Why is this "breaking news" (Score:5, Funny)
Parent
Pluto demoted? (Score:3, Funny)
That changes everything (Score:5, Funny)
Re:That changes everything (Score:5, Insightful)
Parent
So why does Neptune qualify? (Score:5, Interesting)
Re: (Score:3, Insightful)
Re:So why does Neptune qualify? (Score:5, Informative)
Parent
Re: (Score:3, Informative)
http://www.google.com/search?q=pluto+neptune+reson ance [google.com]
http://en.wikipedia.org/wiki/3753_Cruithne [wikipedia.org]
Re:So why does Neptune qualify? (Score:5, Informative)
Parent
Re: (Score:3, Informative)
Son of a B*****!!! (Score:3, Funny)
Teaching about Pluto in School (Score:3, Interesting)
I got in similar trouble to telling my teacher that her solar system model was wrong because all of her planets were on the same plane. And, got in more trouble when I mentioned that Pluto is not the furthist planet from the sun, but rather Neptune was (at least, at that time). Of course, the worst was when I corrected a teacher whom said Saturn was the only plane
Courtesy correction to terminology (Score:3, Funny)
Actually, "dwarf planet" is considered rude.
It prefers to be called a "little planet".
(And besides, if Pluto is going to be the dwarf planet, which planet do the elves get? Or the hobbits? Won't someone think of the hobbits?)
Napoleon... (Score:3, Funny)
I don't like this at all.
You IAU bastards! Now, My Very Educated Mother no longer Just Sat Under Napoleon's Picture. Now, My Very Educated Mother Just Sat Under Napoleon.
You guys are sick. Leave my mother out of this.
Holst was right. (Score:5, Funny)
Anyone? Anyone? (Score:4, Interesting)
Pluto is automatically disqualified because its oblong orbit overlaps with Neptune's.
1) - Is it possible for Pluto and Neptune to one day (like within the next couple billion years) collide? Or are their respective orbits degrading to the point where by the time they'd be near each other orbit-wise, their orbits would no longer overlap significantly? Or by 'overlap' do they mean "diagrammatically speaking, on a two-dimensional representation they overlap but even at their closest possible point they're still a squillion miles away from each other"?
2) - If so, how cool would that be? Would it be funny enough to make it onto an America's Funniest Home Videos video montage? Would it need special clown-horn-honking sound effects?
3) - Considering their distance from Earth and their relatively small size, would a collision of the two have any noticeable effect here on Earth?
4) - Seriously, how cool would worlds colliding be?! Costanza jokes aside, I think it'd be awesome to the max.
Re:Anyone? Anyone? (Score:4, Informative)
Is it possible for Pluto and Neptune to one day (like within the next couple billion years) collide?
Nope. Their orbits are in 3:2 orbital resonance [wikipedia.org]; basicly this means they constantly miss each other (a bit like your average commuter bus and train schedule :P). Also, due to the declination of the Pluto orbit it doesn't even touch the Neptune orbit. When seen straight from above, the orbits overlap, but if you go off-angle to just the right spot the Pluto orbit can be seen to be completely separated from Neptune.
Parent
Pluto and Neptune (Score:3, Insightful)
Doesn't that mean that Neptune also hasn't cleared it's neighborhood? It's orbit overlaps that of Pluto. So why is IT a planet?
Re:Stupid (Score:5, Insightful)
Given the level of scientific illiteracy, what the hell is the point of taking something that everyone does know and declaring it to be wrong?
"Everyone" knew there were eight planets prior to 1930. Did the world end when it was changed to nine, especially with something that wasn't even obviously a planet?
Guess what? A whole generation of children will grow up with the new, consistent rules and won't know any different. What's unarguable is that the new rules are better. I'm all in favor of fixing things that are broken, even if certain curmudgeons are too mentally inflexible to make the adjustment. See also: the metric system in the US, which is kept down by the same curmudgeons.
Parent
Re:Ok, so no we have... (Score:4, Funny)
Parent
Re: (Score:3, Informative)
Re:my take on it: (Score:4, Interesting)
I'm assuming for the moment that it was misreported. The real problem with Pluto is the thirteen other known Plutinos -- objects not gravitationally related to Pluto, but also in highly elliptical Neptune-cossing orbits with a 3:2 resonance to the Neptunian orbit.
Now, there are a bunch of objects which have stable solar orbits with a period the same as Mars. But in the case of Mars, they all either orbit Mars itself, Sol-Mars L4, or Sol-Mars L5. Same can be said for Jupiter, Saturn, Uranus, and Neptune (and Earth, except the "bunch", since Earth only really has the Moon).
Instead, Pluto is like Ceres, which has a number of objects in the same orbit which are all more-or-less doing their own thing. Demoting Pluto now that we know about the Plutinos is like the demotion of Ceres after the discovery of a bunch of other asteroids in the same orbit.
Parent
The problem is that the public wasn't right. (Score:3, Insightful)
No. We've known for decades that the "planet" Pluto was far smaller than any other planet and made of fundamentally different stuff. And through all that time, astronomers let it go because every time one of them mentioned that Pluto wasn't really a planet he was shouted down by the public. Now that we know there are dozens of bodies just like Pluto - and some even larger - what little scientific ac