[Sourbook]

About 3,000 astronomers and scientists are meeting in Prague this week to debate (among other things) whether '2003 UB313' (aka Xena) should be considered the 10th planet in our solar system. Or whether Pluto should even be considered a planet at all. Soon Pluto could be demoted from the ranks of planets to a mere minor planet, asteroid or planetoid.

Plenty more like Pluto

Astronomy is making a mockery of the idea that there are only nine or 10 planets orbiting the sun

It's time we admitted that accepting Pluto as the ninth planet was a big mistake. The announcement from the Lowell observatory in 1930 that a distant new planet had been found in accordance with the prediction by the observatory's founder was a brilliant exercise in public relations. Little heed was paid to critics who soon pointed out that the object was much smaller than Percival Lowell had claimed and that there was no way he could have made a meaningful prediction.

The number of planets has been reduced before. The ancients recognised seven - and in some languages these are still equated with the days of week. After the Copernican revolution the objects associated with Sunday and Monday were dropped and the earth added, so the total became six. William Herschel's discovery of Uranus restored the count to seven. The addition of the four tiny bodies Ceres, Pallas, Juno and Vesta early in the 19th century raised it to 11. Most astronomy books were still counting 11 planets four decades later.

Although the discovery of Neptune provided a significant addition, the avalanche of discoveries of more and more small bodies between Mars and Jupiter made it essential to deal with them in a different way. The Royal Astronomical Society recatalogued Ceres as Minor Planet No 1, and the then latest discovery of Thalia was No 23. The minor planets, which are also called asteroids or planetoids, have now been catalogued up to No 134,339.

As the 20th century rolled on, astronomers established that it would take more than 20 Plutos to produce a planet having even the small mass of Mercury. Furthermore, Pluto is just one object in an extensive region beyond Neptune. It would only be a matter of time before we found something out there larger than Pluto. A year ago the announcement was made of the discovery of a larger body more than three times farther away. Should that object - unofficially dubbed "Xena" - therefore be considered "the 10th planet"?

While that would be understandable if Pluto were to remain the ninth, there is every reason to expect that many larger bodies will be found. To keep adding them to the list of major planets would repeat the mistakes of the past. They should instead be catalogued using the International Astronomical Union's system for tracking minor planets.

Nevertheless, not only schoolchildren brought up on Disney cartoons but even some astronomers who should know better wax sentimental over Pluto's special place. Can we perhaps enact a compromise? How, indeed, should we define "planet", without its qualification as "major" or "minor"? One promising avenue to explore is that planets are basically round in shape. They rotate, and gravity holds them together. How small can they be? Certainly they can be the size of Pluto, nicely round and 2,400km across, and even smaller than the 1,000km Ceres.

So the compromise could be that we have in our solar system four "terrestrial" or "rocky midsize" planets (Mercury, Venus, Earth and Mars). We also have four "jovian" or "gas giant" planets (Jupiter, Saturn, Uranus and Neptune). In between we have some "cisjovian" or "rocky dwarf" planets (certainly Ceres, probably Pallas and Vesta, and perhaps four or five more). Then we have a larger bunch of "transneptunian" or "icy dwarf" planets. This is the realm of Pluto, its companions Orcus and Ixion, and a handful of other bodies including "Xena".

How many planets do you want? I'm perfectly happy with eight. It makes no scientific sense to have nine or 10. I could compromise with 23, or perhaps 39, but such numbers will surely have to increase in the future.

Brian Marsden, The Guardian
http://www.guardian.co.uk/commentisf...843914,00.html

[lavar78]

No, he's a dog!

[Tyre MacAdmin]

As long as Pluto fits the discription I would see no reason to change it. I belive 2003 UB313 orbits on a rather skewed orbit though.

[black bear theory]

i guess it depends on what the definition of "is" is...

[smacintush]

Originally Posted by Tyler McAdams

As long as Pluto fits the discription I would see no reason to change it. I belive 2003 UB313 orbits on a rather skewed orbit though.

I think that the point is that until recently there was no real attempt for a universal "definition" of a planet, so the definition has to be determined objectively first.

Personally, with the quality of instrumentation in the '30's and total lack of follow up after its discovery I wouldn't call it a planet. I would consider it just another space object we aren't sure of. But I'm not an Astronomer so whatever.

[Dr.Michael]

I think the most striking features of Pluto are the very unusual excentricity of this elliptic path around the sun and the fact that Pluto rotates in a different plane than all other planets (I think 17 degrees away from the ecliptic ).

This always led to assumptions that pluto was only a meteor or a comet that has been captured by the suns gravity as he flew by.

The best known photos of Pluto have been made by hubble.

http://www.solarviews.com/raw/pluto/pluto4.gif

(please note that the photos are the two upper pictures. The lower pictures are extrapolations).
This looks quite regular, doesn't it?
So if Pluto is sperical like any other planet, things look different again. Then it may have been created together with the other planets of the solar system.

We will have to wait for more facts until New Horizons reaches Pluto (in 2015).

[starman]

This debate's been going on for years. Every now and then they try to decide if they should rewrite every astronomy text of the last 50 years and every time it fails.

[smacintush]

Originally Posted by starman

This debate's been going on for years. Every now and then they try to decide if they should rewrite every astronomy text of the last 50 years and every time it fails.

You say that like they shouldn't be doing it. If pluto is actually nothing more than a captured comet or something then they should be re-written, and until that can actually be determined it should be de-listed.

[imitchellg5]

Originally Posted by lavar78

No, he's a dog!

Oh, I agree. Doesn't anyone ever watch TV?

[mitchell_pgh]

1) They should have a clear definition of what a planet is. [this IS science... isn't it]
2) They should apply that definition to all objects in our solar system.
3) They should offer a new list of plants.

I would rather see it be 8 planets as compared to 10+ (14 or more) planets, but that's just me.

[Gossamer]

Either way, I'll contiue living.

[Eug Wanker]

[Dr.Michael]

Originally Posted by Eug Wanker

images removed

When I see this stupid nonsense, I want to deregister. Immediately. How does it work?

[brassplayersrock²]

thank you for my new desktop picture eug. my niece LOVES Pluto

[Peter]

my niece LOVES uranus

[jckalen]

As far as re-writing astronomy books, we've certainly had to do that before... like when we figured out the earth wasn't flat, or when we realized that it revolved around the sun, or as we've continued to discover moons (including Charon), or when we figured out there were no canals on Mars, or so on and so on.

But on that note... I'd be inclined to leave it as a planet simply because it does have it's own satelite. Seems like that would be really rare for a trapped asteroid.

[Eug]

Originally Posted by Dr.Michael

When I see this stupid nonsense, I want to deregister. Immediately.

Be sure to shut the door on the way out.

[- - e r i k - -]

Originally Posted by Peter

my niece LOVES uranus

So does your mom. *zing*

[Brass]

They can't de-list pluto. If they did, then "My Very Earnest Mother Just Showed Us Nine Planets" would no longer work. I think that should settle it.

[euchomai]

Originally Posted by Dr.Michael

When I see this stupid nonsense, I want to deregister. Immediately. How does it work?

You just have to have the self-control to not ever visit this site again. I know you won't be able to do it though.

Very pretentious to make sure we all know you are a doctor, even on a message board.

[Sourbook]

Originally Posted by mitchell_pgh

1) They should have a clear definition of what a planet is. [this IS science... isn't it]
2) They should apply that definition to all objects in our solar system.
3) They should offer a new list of plants.

I would rather see it be 8 planets as compared to 10+ (14 or more) planets, but that's just me.

I agree. From everything I've read it sounds like the astronomers are going to come to a firm decision of what exactly defines a planet. I think that they will have to expel Pluto from the ranks. The only alternative would be to allow at least a dozen more into the planetary club. Pluto has recently been thought to be the largest known Kuiper Belt Object (KBO) Xena changed that. Sedna, Quaoar and many others are also sizable KBO's. I think all of them should be lumped into a subcategory of 'planetoid' or 'icy dwarf.' I can live with eight planets.

[His Dudeness]

I don't know many comets that have a satellite orbitting them. To me, that makes Pluto a planet.

[Dakar]

Originally Posted by euchomai

Very pretentious to make sure we all know you are a doctor, even on a message board.

hehehehehe

[Sourbook]

Originally Posted by His Dudeness

I don't know many comets that have a satellite orbitting them. To me, that makes Pluto a planet.

Pluto actually has three satellites in orbit. (two more recently discovered) It's possible in the near future we could discover many KBO's that also have satellites. But without a clear definition of what a planet actually is, we can't go around and slap the title on all of them.

[Monique]

I will be blonde with big jugs; pluto is Mickey's dog, his companion, his best friend how can you say that he is a planet?

[Pendergast]

Originally Posted by Monique

I will be blonde with big jugs;

Monique, meet Dr. Michael.

Dr. Michael, meet Monique.

[SVass]

Only creationist "intelligent design" fanatics ever thought that the world was flat and only those who care worry about whether an object is in the Kuiper Belt or is a "planet". Monique appears to be more interesting. sam

[JoshuaZ]

The question really should be, what kind of cheese are all these new 'planetoids' made out of?

[scaught]

Originally Posted by Monique

I will be blonde with big jugs

post pix

[Gossamer]

Originally Posted by SVass

Only creationist "intelligent design" fanatics ever thought that the world was flat

That's a joke, right?

[brassplayersrock²]

Originally Posted by Peter

my niece LOVES uranus

that's old news

Alex

[mitchell_pgh]

Originally Posted by His Dudeness

I don't know many comets that have a satellite orbitting them. To me, that makes Pluto a planet.

UB313 also has a moon.

[brassplayersrock²]

here's an update:
http://www.clickondetroit.com/seenon...62/detail.html

quote^

"Q: Why is Pluto-Charon a "double planet" and not a "planet with a satellite"?
A: Both Pluto and Charon each are large enough (massive enough) to be spherical. Both bodies independently satisfy the definition of "planet". The reason they are called a "double planet" is that their common centre of gravity is a point that is located in free space outside the surface of Pluto. Because both conditions are met: each body is "planet-like" and each body orbits around a point in free space that is not inside one of them, the system qualifies to be called a "double planet."

Q: Pluto has at least two recently discovered additional satellites that are smaller than Charon. If these smaller satellites also orbit the "barycentre", does this make Pluto a "quadruple planet"?
A: No. The two newly discovered smaller bodies in orbit around Pluto are too small and not massive enough for their self-gravity to force them in to a spherical shape. Therefore neither of these bodies independently satisfies the definition of "planet." The fact that their size (mass) and shapes does not qualify them as planets implies that they must be called satellites, even though the center of gravity (called the "barycentre") about which they orbit is located outside the surface of Pluto."

[tutelary]

They should do the simple thing and make pluto the cut-off point for being considered planet size. Any smaller, its not a planet.

(Why dont I rule the World?)

[Monique]

Seriously it is a discussion between pseudo intellectuals.

[brassplayersrock²]

Originally Posted by Monique

Seriously it is a discussion between pseudo intellectuals.

in other words: a conversation between people who actually understand something and people who don't

Alex

[Eug Wanker]

Originally Posted by Monique

Seriously it is a discussion between pseudo intellectuals.

So you're calling astronomers pseudo-intellectuals?

Or if you're calling us MacNN'ers pseudo-intellectuals that's wrong too, cuz we're too much of a class of clowns to be called even pseudo-intellectual.

[SVass]

For Gossamer: No intelligent person ever believed that the world was flat! Eratothsenes computed the circumference before the beginning of the Common Era.

For the remainder: Is Europe a continent? Is Asia a continent? Is Greenland a continent?

sam

[Sourbook]

Originally Posted by brassplayersrock

here's an update:
http://www.clickondetroit.com/seenon...62/detail.html

Thanks for the link.

If I read this right; Under the new definitions being discussed, Pluto would be considered a Planet, Dwarf Planet and a Pluton. Charon (formally known as a satellite of Pluto) would also be considered a Planet, Dwarf Planet and a Pluton. And both of them collectively could be called a Double Planet, Double Dwarf Planet and Double Pluton. Yet nether one of them, (individually or collectively) would be considered a Classic Planet or Classic Double Planet.

Well that should clear things up.... NOT!

[olePigeon]

Originally Posted by Sourbook

Thanks for the link.

If I read this right; Under the new definitions being discussed, Pluto would be considered a Planet, Dwarf Planet and a Pluton. Charon (formally known as a satellite of Pluto) would also be considered a Planet, Dwarf Planet and a Pluton. And both of them collectively could be called a Double Planet, Double Dwarf Planet and Double Pluton. Yet nether one of them, (individually or collectively) would be considered a Classic Planet or Classic Double Planet.

Well that should clear things up.... NOT!

Sure it does.

We have 12 planets. 8 "classic," one "dwarf," and 3 "Plutons."

Planets: Mercury, Venus, Earth, Mars, Ceres, Juptier, Saturn, Uranus, Neptune, Pluto, Charon, and Xena.

Classic: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.
Dwarf: Ceres
Plutons: Pluto, Charon, and Xena.

Ceres is a dwarf planet because it's smaller than Mercury, but not a Pluton because it's larger than Pluto.

It would appear that Quaoar, Orcus, and Sedna are still under consideration. We could have as many as 6 Plutons and a total of 15 planets.

[Sourbook]

The tide may be turning in favor of the Eight Planet Solar System. I for one will be content with one less planet in the neighborhood.

Pluto may lose status as a planet
By DENNIS OVERBYE, The New York Times

Pluto was looking more and more like a goner on Tuesday as astronomers meeting in Prague continued to debate the definition of a planet.

"I think that today can go down as the `day we lost Pluto,"' said Jay Pasachoff of Williams College, in Williamstown, Mass., in an e-mail message from Prague.

Under fire from other astronomers and the public, a committee appointed by the International Astronomical Union revised and then revised again a definition proposed last week that would have expanded the number of official planets to 12, locking in Pluto as well as the newly discovered Xena in the outer solar system, as well as the asteroid Ceres and Pluto's moon Charon.

The new definition offered on Tuesday would set up a three-tiered classification scheme with eight "planets"; a group of "dwarf-planets" that would include Pluto, Ceres, Xena and many other icy balls in the outer solar system; and thousands of "smaller solar system bodies," like comets and asteroids.

The bottom line, said the Harvard astronomer Owen Gingerich, chairman of the Planet Definition Committee of the IAU, is that, in the new definition, "Pluto is not a planet."

"There's not happiness all around, believe me," he added.

The new proposal was hashed out in a couple of open meetings, the first of which was described by participants as tumultuous, and the second as more congenial. Astronomers are supposed to vote on Thursday on this or some other definition, but whether a consensus is emerging depends on whom you ask. Some astronomers expressed anger that the original definition of a planet had been developed in isolation and then dropped on them only a week before the big vote. Others continued to question whether it was so important to decide the question now.

Among its defects, some astronomers say, the newer definition abandons any pretense of being applicable to planetary systems beyond our own solar system.

To many astronomers, Pluto's tiny size and unusually tilted orbit make it a better match to the icy balls floating in the outskirts of the solar system in what is known as the Kuiper Belt than to the traditional planets like Jupiter and Mars.

LA Daily News - Pluto may lose status as a planet

[C.A.T.S. CEO]

yes

[Peter]

its official
Astronomers Say Pluto Is Not a Planet
Must suck to be pluto right now...
Guess the wikipedia article on Pluto should be nominated for deletion... "no longer notable"

[Visnaut]

I have no problem with readjusting my definition of the solar system, so long as there are logical reasons for doing so, not emotional ones. Adjusting the definition simply for the purpose of mainting Pluto as a "planet" is rather short-sighted. All it does is prolong the true breakdown of objects in our solar system.

I think it's rather logical if it were broken down into:

• 4 Rocky Planets
  • Mercury
  • Venus
  • Earth
  • Mars
• 4 Gas Giants
  • Jupiter
  • Saturn
  • Uranus
  • Neptune
• 4+ Planetoids
  • Ceres
  • Pluto
  • Charon
  • Xena

I think that's about as logical and fair as it gets. We get an accurate classification of all planets, and it's not like we're relegating Pluto and others outright to asteroid status.

[Visnaut]

double post

[mitchell_pgh]

Originally Posted by Visnaut

I have no problem with readjusting my definition of the solar system, so long as there are logical reasons for doing so, not emotional ones. Adjusting the definition simply for the purpose of mainting Pluto as a "planet" is rather short-sighted. All it does is prolong the true breakdown of objects in our solar system.

I think it's rather logical if it were broken down into:

• 4 Rocky Planets
  • Mercury
  • Venus
  • Earth
  • Mars
• 4 Gas Giants
  • Jupiter
  • Saturn
  • Uranus
  • Neptune
• 4+ Planetoids
  • Ceres
  • Pluto
  • Charon
  • Xena

I think that's about as logical and fair as it gets. We get an accurate classification of all planets, and it's not like we're relegating Pluto and others outright to asteroid status.

I agree. We should stick to pure science on this issue. Make clear classifications, and apply those classifications to ALL items in our solar system.

The people arguing UB313 isn't a planet but Pluto is are making emotional responses.

[nonhuman]

My Very Excellent Memory Just Served Up Nine ... damnit!

[forkies]

Originally Posted by Peter

Must suck to be pluto right now...

no ****, SCREWED!

[analogika]

Originally Posted by Visnaut

[*]4+ Planetoids

• Ceres
• Pluto
• Charon
• Xena

[/list]
I think that's about as logical and fair as it gets. We get an accurate classification of all planets, and it's not like we're relegating Pluto and others outright to asteroid status.

So what's the distinction between "small solar system bodies" and "dwarf planets"?

[olePigeon]

Originally Posted by Peter

Must suck to be pluto right now...

I don't think Pluto cares. It's a rock.