Dwarf Tossed: Pluto, 1930-2006

Just a week ago, the farthest biggish object in our solar system was not only poised to continue its life as a planet but on the verge of being joined by Charon, Ceres, Xena, and "scores" of other new planets in the AA-league of "Plutons."

Now, the shameless size queens at the International Astronomical Union have voted to demote Pluto to the status of "dwarf planet," leaving us with a mere eight fully accredited planets in the solar circus. Patricia Tombaugh, 97-year-old widow of Pluto discoverer Clyde Tombaugh, pronounced the news "disappointing" and "confusing," and I'm a little skeptical of the idea that having a moon, not to mention three moons, doesn't qualify you as a planet. Union regulations indeed! The new planetary guidelines provide some explanation:

Pluto, a planet since 1930, got the boot because it didn't meet the new rules, which say a planet not only must orbit the sun and be large enough to assume a nearly round shape, but must "clear the neighborhood around its orbit." That disqualifies Pluto, whose oblong orbit overlaps Neptune's, downsizing the solar system to eight planets from the traditional nine.

Astronomers have labored without a universal definition of a planet since well before the time of Copernicus, who proved that the Earth revolves around the sun, and the experts gathered in Prague burst into applause when the guidelines were passed.

Diehard Plutonians are not taking the news lying down. "It's a sloppy definition. It's bad science," says Alan Stern, head of NASA's $700 million New Horizons project, which will send a probe to the 76-year-old dwarf planet. "It ain't over." Pluto supporters note that only 300 of the IAU's 2,500 astronomers attended the vote.

Dwarfs stand up for their right to get tossed.

The lowdown on that other Pluto.

Or that other Pluto. Or as Mickey Mouse said of Minnie in divorce court: "I didn't say she was insane, I said she was fucking goofy."

Comments

[Hmmm]

The benefit of the previous proposal was the in addition to providing a definition of planet, it was set to provide the first practical definition of a binary planet system. Now it remains ambiguous and the status of the Pluto-Charon system is not entirely clear.

[Clyde Tombaugh]

It's an outrage! I'll discover another one if this persists!

[Pro Libertate]

Neil Tyson wins the war with Colbert! See the Bad Astronomer's discussion of this important debate.

[MikeP]

Yay!

As I commented on that last Pluto thread...

I am willing to lose Pluto so as not to gain a hundred plutons.

Maybe that was the committee's intent... "You know, Pluto isn't really a planet." "You know that and I know that, but a hundred million schoolchildren and their parents will be really ticked off if we demote it." "I've got an idea. Let's come up with something so stupid that it calls Jupiter and some silly piece of ice 30 billion miles away both planets. Everyone will hate it! Demoting Pluto will seem tame by comparison." "Excellent! Great idea, Dava Sobel!"

[raymond]

My very excellent memory just served up nine planets.

I'm screwed.

[Hmmm]

MikeP,

As evidence grows about the overwhelming complexity of our solar system, I'm not sure if the distinction between objects that do and do not constitute major planets is any more useful than Aristotle's classification of all motion as either violent motion or natural motion. The fact of the matter is that while Pluto is very different from the classical eight, it bears some important characteristics just as Earth is similar in some ways to Jupiter but still in a wholly different category than the gas giants.

[Don Coyote]

Rumor has it that the Plutoites are up in arms over this. The space station is now on threat level Orange. Haliburton has been notified.

[NoStar]

The new definition is not well thought out, nor is it being applied well. Shouldn't Neptune be disqualified for not having cleared Pluto from its orbit?

[Neu Mejican]

I used to live down the street from Clyde T.
He was the coolest man you could ever meet.
For that reason alone, I think it is sad that his discovery has been given "dwarf" status. I'll argue that a dwarf planet is still a planet, just as a gas planet is a planet (for Clyde's sake). I actually like the term better than "Pluton."

[MikeP]

Just to whine about something, what I don't like from these definitions is the notion of "dwarf planet".

First, it carries the word planet around, as though "dwarf planet" is a subset of "planet". Poor semantics.

But more importantly, the definition persists in latching on to the notion that the marginal round solar system body is different enough from the marginal nonround body that it deserves a different label.

Ceres is an asteroid. Xena is a Kuiper belt object. Why classify them together because they both happen to be round?

An exercise for the reader: What is the smallest object that can be called a dwarf planet by this definition? My entry is a body mostly composed of mostly depleted uranium. The density and ductility of the metal would be enough to round it out. But if it keeps itself extremely warm due to its being a natural fission reactor, then it's almost guaranteed to be round -- even if it's only a couple miles across!

[MarkV]

Pluto: The Rodney Dangerfield of planets.

I bet when New Horizons finally snaps a good picture of the orb, we'll see two bulging eye-like craters and a long red valley tied around its equator.

[crimethink]

I'm a little skeptical of the idea that having a moon, not to mention three moons, doesn't qualify you as a planet.

Actually, Tim, the mid-sized, enema-bag-shaped asteroid Ida has a moon, and the Kuiper Belt object "Xena"/2003-UB313 has two of them, and there are probably more minor Solar System objects with satellites we just haven't discovered yet.

As far as the "clearing the neighborhood of its orbit" business, I'm just wondering why Neptune didn't get docked as well, since it hasn't cleared Pluto out of its orbit.

[MikeP]

Hmmm,

Actual astronomers of course care little for the labels. Nothing important to science is lost or gained in most any definition.

But the vast majority of people who need mnemonics to remember the planets will at least get an understanding of those eight most important bodies rather than deal with 12 or 53 or 300 bodies called planets. The discoverer of Xena noted that the whole episode is actually pretty educational in that it shows that science adapts as new knowledge becomes available.

The fact of the matter is that while Pluto is very different from the classical eight, it bears some important characteristics just as Earth is similar in some ways to Jupiter but still in a wholly different category than the gas giants.

PBS is running a commercial for a fall show where Neil deGrasse Tyson talks to people on the street. To one person he notes that, if Pluto were where Earth is now, it would have a tail.

[MikeP]

Pluto is not in Neptune's orbit. It's not even in the same orbital plane.

[Pluto, Son of Gloin]

Toss me.

I cannot clear the orbit, so you're going to have to TOSS ME!!!!

[aspendougy]

So Pluto can't clear out its own space for an orbit? It's like comparing Karl Malone to Allan Iverson going to the basket. Allan can't clear out a space when he drives to the basket like the former "Mailman", but hey, he gets the job done! Pluto is kind of like Allan Iverson, a scrawney and knobby-kneed planet, but it works.

[crimethink]

MikeP,

Actually you're right, but it seems that the reasoning behind excluding Pluto is that it has not cleared Neptune out of its orbit; and if Pluto is not in Neptune's orbital plane, neither is Neptune in Pluto's orbital plane.

[MikeP]

In fact, the orbits of Neptune and Pluto never even intersect.

I sure hope the nineplanet.org folks own the domain name eightplanets.org too...

[Mad Scientist]

I'd really like to see the definition of a "cleared orbit." If it means there's no junk in the orbit which the plant can run into, that disqualifies all 8 of the remaining planets as well.

MikeP, Pluto crosses the ecliptic plane, so it's entirely possible that one day in the far off future it and Neptune could go whack, way out there in the darkness. I agree with NoStar and crimethink: Neptune should be disqualified too under this definition.

[Mad Scientist]

Ooo, good link. I stand corrected. But that just makes the reasons for disqualifying Pluto and not Neptune all the more suspect.

[MikeP]

it seems that the reasoning behind excluding Pluto is that it has not cleared Neptune out of its orbit; and if Pluto is not in Neptune's orbital plane, neither is Neptune in Pluto's orbital plane.

I assume that you are referring to Tim's quoted

That disqualifies Pluto, whose oblong orbit overlaps Neptune's, downsizing the solar system to eight planets from the traditional nine.

The only reference I have seen to anything like this is that sole AP article. For instance, the space.com article says nothing of the sort:

Pluto and its moon Charon, which would both have been planets under the initial definition proposed Aug. 16, now get demoted because they are part of a sea of other objects that occupy the same region of space. Earth and the other eight large planets have, on the other hand, cleared broad swaths of space of any other large objects.

I think you should view the quoted "whose oblong orbit overlaps Neptune's" as simply descriptive and not part of the reasoning.

[Robert]

I was really hoping for a thread about dwarf tossing in France.

[MikeP]

I'd really like to see the definition of a "cleared orbit." If it means there's no junk in the orbit which the plant can run into, that disqualifies all 8 of the remaining planets as well.

That space.com article [link fixed] has some criticisms along those lines.

[kevrob]

I would have gone with this headline:

Pluto gets Dissed

Kevin

[thoreau]

Here's where we need to remember Richard Feynman's admonition about the difference between knowing the name of something and actually understanding it.

[crimethink]

MikeP,

I'm not sure if they count as "large" objects, but wouldn't the Trojan asteroids threaten Jupiter's planetary status then?

[crimethink]

MikeP, sorry, I didn't RTFA...

[MikeP]

I'm not sure if they count as "large" objects, but wouldn't the Trojan asteroids threaten Jupiter's planetary status then?

While the Trojans and even Earth's own companion Cruithne are not cleared from their respective planet's orbit, they are totally dominated by their respective planet. Even the moons of each planet are not "cleared" from the planet's orbit. They travel in orbits around the sun that are almost identical to their planet's. Certainly moons should not disqualify a planet.

Perhaps the definition of planet should be revised to say "has cleared or dominated all smaller bodies in the neighborhood around its orbit."

[Col DuBois]

The IAU is just asking for a Nightfall-type ending here.

[Deus ex Machina]

Yet another humiliation suffered by the Plutonians.

[Ruthless]

We humanoids were able to make this fine distinction within the space of one Plutonian "season."
Pretty snappy are we, say I.

It's time anyway to focus on planets orbiting other stars, eh?

[Pro Libertate]

Pluto's just another Kuiper Belt object, now.

It's interesting how newsworthy this has become. Nothing's changed at all except a label. Where's Wittgenstein when you need him?

[MarkV]

Pushin' up daisies, most likely.

[Stevo Darkly]

Personally, I love the idea of a "dwarf planet," and I would like to visit one.

Although it would probably be pretty noisy, what with all the banging of picks against rock, and the entire population singing, "Hi ho, hi ho ..." But everyone would look up to me.

[Franklin Harris]

From Space.com:

Stern, in charge of the robotic probe on its way to Pluto, said the language of the resolution is flawed. It requires that a planet "has cleared the neighborhood around its orbit." But Earth, Mars, Jupiter and Neptune all have asteroids as neighbors.

"It's patently clear that Earth's zone is not cleared," Stern told SPACE.com. "Jupiter has 50,000 trojan asteroids," which orbit in lockstep with the planet.

Stern called it "absurd" that only 424 astronomers were allowed to vote, out of some 10,000 professional astronomers around the globe.

"It won't stand," he said. "It's a farce."

Stern said astronomers are already circulating a petition that would try to overturn the IAU decision

***

Me again:

And what if we find a binary planet system of gas giants out there somewhere? (OK, I don't know the math, so such a thing may not even be stable, but follow me on this.) Is anyone going to seriously claim that two objects orbiting each other aren't planets even if they're both the size of Jupiter?

[Deus ex Machina]

Perhaps Stern is a little perturbed due to the realization that he has sent a billion dollar probe to what is now a large chunk of ice.

[John]

I agree with the Feynman and Wittgenstein references to the effect that names and labels do not bring about real understanding. But am I the only one here happy with this decision? Pluto still exists. You can still fly out to it and have a nice vacation. But why not have a nice, clear-cut, if of course arbitrary, definition?

PS: Neptune is still the /major/ body in its orbit. Pluto is not.

[Syd]

If dwarf planets are not planets, then are red dwarf stars not stars?

The sun is a yellow dwarf. That means it punches you in the kneecap and runs like hell.

[MikeP]

Neptune is still the /major/ body in its orbit. Pluto is not.

Indeed, if their orbits did happen to intersect exactly, one of them would have a hole in its cloudtops and the other would no longer exist. If they merely had a close encounter, one of them would still be a planet and the other would become either the most impressive comet in human history or the largest named object to leave the solar system.

And, by the way, Charon would bite it too.

[Stevo Darkly]

By the way, they found out late last year that, in addition to the moon Charon, Pluto also has two smaller moons that have been named Nix and Hydra. (I didn't know that until I did some Googling tonight.)

[MarkV]

Hey! Keep your Googling to yourself!

[James Anderson Merritt]

Crimethink said, "As far as the 'clearing the neighborhood of its orbit' business, I'm just wondering why Neptune didn't get docked as well, since it hasn't cleared Pluto out of its orbit."

That was my first thought when I heard the news, as well. It would seem quite possible for a planet to be askew from the plane of the solar system, perhaps intersecting the orbits of a couple of "legitimate planets," and still itself be a planet, with speherical shape, a fairly large mass of its own, and moons. Its intersections with other planetary orbits might mark it as a catastrophe waiting to happen, but until then, would it not be a planet?

I don't see why there is a problem with having MORE planets, rather than fewer. But the astronomical community (or at least those who voted) seem to have a conceptual difficulty with the dwarf planets. Perhaps it is time for new astronomers.

[Rick Barton]

The triviality of this matter is beyond the scope of Feynman's admonition about the difference between knowing the name of something and understanding it, and Wittgenstein's observations concerning labels.

Actually, science does fruitfully classify things and it is often a salient matter when an object is reclassified. We might anticipate different behavior and try new things with an object when we know that it we put in a group that it didn't belong. The different grouping might also have implications for the object's origins.

But this Pluto matter is different! Here we have the definitions of what constitutes a planet being changed retroactively so as to exclude Pluto. And some of these new definitions seem rather ambiguous...

...clear the neighborhood around its orbit.

and even silly...

A planet not only must orbit the sun and be large enough to assume a nearly round shape

If, say, Mars had had a rather unfortunate prehistoric encounter with an asteroid that left it misshapen and lots smaller, and so that it's pre-collision shape couldn't be determined, I don't think that this part of the definition would have been put forth.

Now Pluto's orbital plane is 17 degrees off the horizontal plane taken by the eight other planets and its path around the Sun is so egg-shaped that for 20 years of its orbit Pluto tracks inside the orbit of Neptune.

And this fact points to a better reason for Pluto's re-classification: Pluto has a different origin than the other planets. It's not really a member of the solar system..

The other planets formed from the same revolving disk of gas. Pluto is a Kuiper Belt Object that formed from an outer sphere of gas. It is among the largest of these and the closest. So, whether we call it a Kuiper Belt Object and not a planet, based on its origins, or a planet and then note that it is a Kuiper Belt Object, we can still thank Mrs. Tombaugh for Clyde's wonderful discovery of remarkable Pluto.

[Rick Barton]

...So, How about we still call Pluto a planet while noting that it isn't a member of the solar system but is a Kuiper Belt Object.

Oh damn, I just thoughta something. How would I classify comets? Especially ones with orbits shortened by gravitation. Would I not consider them to be members of the solar system?...What Feynman and Wittgenstein said... I wanna crash.

[Deus ex Machina]

How much longer till the Right-wing media denounces this as a European plot to denigrate the only planet to be discovered by an American?

[MJ]

"I don't see why there is a problem with having MORE planets, rather than fewer."

Because there are potentially a very large number of undiscovered Pluto-like objects out in far reaches of the Solar System. One Pluto gets a pass as a planet, a dozen renders the term planet a bit absurd.

Perhaps Pluto would have retained its status if were not so odd compared to the other eight, particularly with regard to it's highly eccentric orbit out of the plane of the ecliptic.

[gaijin]

Hope all the school systems have lots of money for the new textbooks that must be published.

[Mr. F. Le Mur]

We can thank Microsoft's crummy dictionary for the name:

"According to a story over at Nature, some geologists are ticked off at the International Astronomical Union for using the word 'pluton' to describe a round object orbiting the sun with a period more than 200 years. A pluton, it seems, is a common type of rock formation that exists in most Geology 101 curricula. IAU head Owen Gingerich is quoted as saying that he was only peripherally aware of the definition, and because it didn't show up on MS Word's spell check, he didn't think it was that important."
Originally at:
http://localhost/blosxom.cgi/topics/humor/pluton_msword_debate_2006.html
which ain't working right now.

[Slainte']

Deus ex Machina your comment actually has a sliver of truth behind it.

The story-behind-the story about Pluto is that Pluto was discovered at an at-the-time mostly privately-funded observatory run by Percival Lowell. He was somewhat outside the mainstream of astronomers. (He's the guy who made detailed maps of Mars' supposed "canals".) His science was somewhat tainted in the eyes of other astronomers. The discovery of Pluto was upsetting to them, who quickly attacked it as an accidental find, and not the source of the perturbations of Neptune. Some in the astronomy community have had a grudge about Pluto for years. (No, I'm not kidding.)
This was a opportunity for a posthumous smackdown of Percival Lowell. (And others who they see as planet-finder glory seekers.)

[Pro Libertate]

Some day, thousands of years from now, Pro Libertate Mark VI (I will be downloaded to a positronic brain in a robot body in 2040) will use this ruling to evade the laws governing "planets" by reforming Mars into a large cube. Not a planet, 'cause it's not spherical! Space lawyers will shake their brainboxes in envy of my computer-enhanced brilliance.

In other news, it's pretty clear that astrologers aren't going to start ignoring Pluto. If they did, then that would mean that all of their predictions to date were based on faulty data. So I'm betting that astrology in general will reject the non-planet designation for Pluto.

[D.A. Ridgely]

By the way, they don't like to be called "dwarf planets" but prefer "little people planets."

[acg]

Just as long as they don't get rid of Uranus; because, like, the universe wouldn't be complete without Uranus. And the rest of you too.

[SR]

"How much longer till the Right-wing media denounces this as a European plot to denigrate the only planet to be discovered by an American?"

Shoot, that's a good one! I'm forwarding it to O'Reilly's tip-line as we speak.

[The Lonely libertarian]

With depravity,
I break laws of gravity
Blast past the atmosphere
to the last frontier
I go boldly through space and time
The sky's the limit,
but they're limiting the sky
I break orbit by habit,
I ignite satellites and leave rings round the planets
A flying ace like that beagle,
nevertheless this alien remains illegal
Cause their discovery don't cover me
the immigrants been left in the cold
to grow old
and disintegrate
Discriminate
against the distant and disclaim us,
Cause small minds can't see past Uranus
But I shun their race
cause that's just a phase
and my odyssey runs in 2001 ways
And I can see clearly now like Hubbell
shoved off the shuttle,
here's my rebuttal
It's a planet.

Who you represent?
I represent the smallest planet
Attorney in this tourney
versus those who tried to ban it.
If you don't agree
go see interplanet Janet Cause
the sun is star like
Pluto
is planet.
So lend me all ears
and let me state my case,
about all the types of satellites we must embrace
Cause like parents'
great-grandparents,
this planet was an immigrant,
to deport it's an offense.
It's an upstanding member of the solar system
Abide the laws of Earth and make it a victim.
It's a proposition
187,
When Pluto spawns a moon it will apply to the heavens.
Abandoned like Judas of Iscariot
If you demote this mote to affiliate
It's like taking ET's custody from Elliot,
Support your Lilliput, 'cause simply put

Pluto is a planet

Do it for the children
(If not for yourselves)

Pluto is a planet. Pluto!
Pluto is a ....

[Jaybird]

Another example of George Bush's America trying to take us back to the days of Herbert Hoover.

[crimethink]

Slainte,

Let's see, Percival Lowell was already dead when Pluto was discovered, and it was named Pluto partly to honor him with its first two letters, despite the machinations of the vast astronomical conspiracy.

And the "attacks" against Pluto's ability to perturb Neptune's orbit were in fact correct; the putative perturbations of Neptune's orbit were actually an illusion created by the use of an incorrect estimate of Neptune's mass.

[Pro Libertate]

Hey, "P.L." are my initials, too! Pluto's status must be restored by any means necessary. The Popular Plutonian Liberation Front is born!

Rev-v-venge!

[James Anderson Merritt]

I said, "I don't see why there is a problem with having MORE planets, rather than fewer."

MJ said, "Because there are potentially a very large number of undiscovered Pluto-like objects out in far reaches of the Solar System. One Pluto gets a pass as a planet, a dozen renders the term planet a bit absurd."

Yes, yes, I've heard the alleged issues in the debate for many years, now. But I disagree with your conclusion: a solar system of many dozen "planets" is not absurd at all. How many undiscovered objects will be larger than Pluto or Xena?

Already, and for many years, planets have been classified as "Jovian," "Terrestrial," "classical," and so forth, so as to winnow down the list under consideration at any one time to a more manageable number. This will always be the case, however many official "planets" we have. If we must label Pluto, Xena, etc., as "dwarf planets," fine. But in my opinion, they are planets first and dwarves second.

I doubt that this classification will stand. Given that only 4% of the membership were in the room when the resolution was passed, it can hardly said to be representative of the AAU "consensus." Heck, you could come up with that many climatologists to declare that there is no such thing as human-induced global warming. Would that necessarily make it so?

[Mrs. Reaver]

And so we found a new solar system -- dozens of planets, hundreds of moons....

[Ayatollah Usoe]

I kind of like this. Maybe we should have term limits for all planets.

[The Earth that was]

Indeed, how long before we're told that there is no Pluto? And it's erased from all the star charts?

[MarkV]

Pluto? What's that?
Things are never 'erased', you are comitting doubleplus bad crimethink.

[Mr. Nice Guy]

Okay, I vote that we switch the names "Pluto" and "Uranus" between the respective bodies.

I am SO SICK of that "Klingon" joke.

[James Kabala]

A relevant datum is that recent years over 200 planets have been discovered orbiting distant stars. See, for example, http://en.wikipedia.org/wiki/Extrasolar_planet. This has come in the discussion here and elsewhere a lot less than I would have expected.

[Pro Libertate]

Oh, we know all about extra-solar planets around here. Our postings are transmitted to one before actually going up on Hit & Run.

[Rick Barton]

Pro Libertate,

Good one!

[Rick Barton]

...Of course this is the best blog extant so we take it in stride.

[Pro Libertate]

I knew things were heart-attack serious with the server when Nick bitched about it in this forum. I mean, that's sad when you're the Editor-in-Chief and can't get anything better than an Apollo-era surplus server. Reason didn't treat Virginia like that, let me tell you. It's all sexism, if you ask me. Oppression. Hegemony.

Nick or Tim--whoever has server influence, as weak as that influence clearly must be--my recommendation is that you secretly set up a PayPal button on the site that, when clicked, allows the clicker to donate funds specifically to the purchase of a high-end, Hit & Run-traffic worthy server. Made of shining Cylon (old school, baby, old school) metal. I'd have clicked the thing 30 times in one day during the nadir of server service that we experienced in recent weeks.

[That's a bad notion]

See that big black band out past Neptune? That's pluton territory. They just float out there, sending out comets every once in a while. Nobody goes out there, not even NASA.

[The Guardian on the Edge of Fo]

Stupid humans. In a few billion years it won't matter anyway.

[Syd]

"See that big black band out past Neptune? That's pluton territory. They just float out there, sending out comets every once in a while. Nobody goes out there, not even NASA.

Comment by: That's a bad notion at August 25, 2006 05:20 PM"

Actually, there's a NASA spacecraft heading toward Pluto.

I move we rename Xena Sneezy.

[Get to work]

Actually, there's a NASA spacecraft heading toward Pluto.

Really? For its sake, I hope they splattered it with red paint and tied some skeletons to the nose...

[Slainte']

Crimethink, I guess this was an example of "if you don't have anything to say, say it anyway."

"Let's see, Percival Lowell was already dead when Pluto was discovered, and it was named Pluto partly to honor him with its first two letters, despite the machinations of the vast astronomical conspiracy."

--WTF?? Who said anything about a vast astronomical conspiracy. I said "some astronomers..."

And the "attacks" against Pluto's ability to perturb Neptune's orbit were in fact correct; the putative perturbations of Neptune's orbit were actually an illusion created by the use of an incorrect estimate of Neptune's mass.

Again, WTF?? "Some" of the attacks came right away, before the size of Pluto was fully known. The facts of Neptune's mass came many years later.

The salient comment you seemed to have ignored is that a small group of (i.e., some) astronomers have had a grudge about Pluto for a long time, and this was an opportunity to excersize that grudge. "Some" of the astronomers who voted may have harbored this grudge.