Dear Friends,

Today I am extremely dissapointed that the Pluto Demoters have triumphed.

I respect their opinion, but disagree with it.

I strongly agree with Alan Stern's statement calling it "absurd" that only 424 astronomers were allowed to vote, out of some 10,000 professional astronomers around the globe.

This tiny group is clearly not at all representative by mathematics alone.

I believe we should formulate a plan to overturn this unjust decision and return Pluto to full planetary status, and as the first member of a third catagory of planets, Xena being number two. Thus a total of 10 Planets in our Solar System

Please respond if you agree that Pluto should be restored as a planet.

ken

Ken Kremer
Amateur Astronomers Association of Princeton
Program Chairman

I'm in.

So am I.

You might want to carefully consider what, if any, counterproposal you make axiomatic to your movement. You might find that a majority support Pluto's planethood, but split with you on other subissues. Or, maybe you have already carefully considered the politics of it. Cheers, in any case.

I noted that in Jason's poll, a plurality of UMSFers voted for a proposal basically identical to the one that passed. However, a number greater than that plurality voted for a more expansive definition (more than 9 planets), but their numbers were split among several proposals. Which demonstrates your point, I think.

I agree, this is an arbitrary ruling by a small subset of astronomers. And who even says that astronomers alone get to decide? How many people involved in space research today have a degree in astronomy?

JRehling makes an important point. Any petition to reverse the ruling is likely to become fragmented by people promoting various different defintions of "planet".

If you don't like Pluto's demotion, consider dwarf planets as a subgroup of the "true" planets (i.e. reversion of the Resolution 5B). Problem fixed.

Besides, only time will tell if people will adopt this definition.

At any rate, I'm in! What if it turns out Pluto and UB313 are the only TNOs over 2000 km in diameter out to several hundred AU? I also agree a new planet class should be created, perhaps one that covers bodies in the 2000-6000 km diameter range. Call it Sub-Terrestrial Planet? Then have bodies smaller than 2000 km called "dwarf planets?" Later!

J P

The obvious way around that is to focus on the results and not the reasoning.

Exactly. My proposal clearly is for a cut-off at 2000 km, 10 Planets known at this time. Thats reasonable and avoids the 43+ planet scenario which Mike Brown correctly points out.

Thanks for the response so far. Looking forward to more.

ken

This could really get messy if they find a Pluto-type world the size of Mercury or larger. Also, the fact that the differences between Mercury and Pluto, for example, generate a distinction, but not the differences between Mercury and Jupiter - this is disturbing.

Poll at chicagotribune.com...

Do you agree with the International Astronomical Union's decision to strip Pluto of its planetary status?

33.6%
Yes (1559 responses)

66.4%
No (3076 responses)

4635 total responses




CNN -

Were scientists correct in downgrading Pluto's status?

Yes - 26170
No - 43737

Not necessarily. There may be many Pluto-sized objects waiting for discovery.

I wonder what the result would have been if the question was "Would you like that Solar system has 50 planets?"

Of course a layman (and many scientists) doesn't want to demote Pluto. It's a purely sentimental issue to him.

Now the work lies making people realize that the "dwarf planets", including the giants in the asteroid belt, are interesting worlds of their own right. Not to forget major satellites.

Hi Alan,

thanks for your valuable contribution.

thats already > 100 x more votes than at the IAU

and I just saw a TV news report showing LOTS of EMPTY SEATS at the Prague Auditorium !!!

that does not impress me (as a fellow scientist) as overwhelming support for the demotion of Pluto.

The Fight for Pluto has begun .... !!!!!!!

as "The First Mission to the Last Planet" rockets outward to the unknown

ken

I for one cheered when I heard the news!

I support the decision.

If it had been up to me, personally, to make a decision on the matter, I would probably have minimally dubbed 2003 UB313 a planet, drawn a lower size limit at 2250 km, and left it at that. If I thought the world was ready for a more meaningful set of designations, I would have mandated breaking up the "planet" group into at least three groups, and maybe more, that were to be considered at least as different from each other as they are from asteroids. I would not have taken any criteria into account other than mass and diameter, and although I probably would not have relabeled large satellites as "planets", I would have provided for a parallel set of divisions for satellites.

However, it wasn't up to me, and I have to say that the only thing seriously wrong with the IAU decision is the "neighborhood clearing" language, which is too obscure to even be useful. It's fair to say that some large objects exert a gravitational influence on smaller objects in their surroundings, which if not as continuous as their influence over their satellites, is in some way comparable. We can certainly say that Jupiter's Trojans are in Jupiter's gravitational sphere of influence, and in a different way Pluto is under the influence of Neptune. I doubt that such spheres of influence can be extended to include every single asteroid and KBO, except in the most general sense, in which all the planets (particularly the giants) have non-negligible influence on the orbits of the others (Neptune's perturbations of Uranus' orbit being a famous example). But we don't want to conclude that Jupiter is the only planet in the Solar system -- doubtless for sentimental and unscientific reasons! I am not sure that even a better definition of what is meant by "orbit clearing" is going to clean this up; if we regarded the orbits of all Solar system objects as alike, without regard to the mass of the objects, I doubt that the "major planets" could be easily picked out of the crowd.

Other than this problematic limitation, I am not terribly perturbed by result of the decision; it was one reasonable decision out of many possible reasonable decisions. I don't think it was the wrong decision; but that doesn't mean that I think it was the right one. I think the real mistake here is to suppose that there are absolutely right or wrong decisions on a topic like this; it's certainly not a moral question, and "Pluto is a planet" is not a statement that can be determined to be true or false in the way that "Pluto has a diameter of c. 2300 km" can be. The category of planet doesn't exist in nature; it's a creation of the human mind, and only has meaning relative to what humans want to make of it.

I don't expect this to be the last word on the question; I think that additional information about the nature of the Solar system, while not fundamentally changing the various rationales used by planetarians and antiplanetarians, may well change the emotional relationship people have to the word "planet". I appreciate that people may have strong feelings on either side of the question, but at present I'm happy to let those people engage. The result of the IAU vote reflects, I think, more politics than science; the antiplanetarians were better organized, more unified, and more passionate than the planetarians, and arrived in Prague prepared to win. Now the planetarians have got a Cause of sorts, and they will have three years to organize before they go off to Rio de Janeiro. Perhaps at that time they will be in a better position - and perhaps not. Public reaction -- especially the public consisting of professional and amateur astronomers -- to the decision is likely to play a role. If people cannot be bothered to do anything but laugh at the decision, then it is likely to stick. If it's generally rejected by ordinary people who have an interest in astronomy, then the IAU may merely have discredited itself. It promises to be an interesting time.

I would have been happy with either of the possibilities they were voting on. If they passed 5B, potentially increasing the count to 50+ or even 100, how many of Pluto's defenders would now be objecting to all the riff - raff they were letting into the club?

Science isnt something that you can start a politisized campaign about, or even worse lobbying!
If you think so, then you're out on very thin ice indeed. If you set this snowball in motion you'd end up to lobby against the gravity or perhaps evolution.
Yes this is no different from the politization of science which have infected the entire matter about not only evolution but also biology in the USA, as a consequence about half dont even know what DNA is.
So isnt it time to come to your senses here?

You cant campaign against a scientific matter, else you are in the same boat with the Intelligent design people that some of you have critisized elsewhere!

That is well and good, but I really don't see how this is a scientific matter. It seems much more cultural/subjective, cloaked in scientific laguage, rendering the gravity/intelligent design arguement analogy out of bounds. Those deal with what is or isnt, or what happened versus what didn't. This debate is over how we want to define the word planet.

Im in!

I dont mind if Pluto is a dwarf planet, but dwarf planets ARE planets. So please call it the fight for the dwarf planets instead of the fight for Pluto

Also on my new planetology comminity site(launched yesterday); http://www.AlphaOrionis.be/ I consider dwarf planets as a type of planets just like the terrestral and giant planets. This is my way of participating in the fight for the dwarf planets.
No matter what, having a dwarf planet section is never wrong on a planetology forum.

C - ommittee to
R - einstate
A - stronomy's
P - luto?

Nah.

S - ociety
L - iberating
O - utermost
P - lanet?

Nah.

C - ommittee
O - rganizing the
R - evitalization of
P - luto's
S - taus

Better.

O - rganization
N - ever

T - olerating
H - eretically
E -xcommunicated

D - iscovery
O - f
T - ombaugh

?

Maybe just Antipluto Defamation League? Pluto Liberation Army?

P - luto:
L - arger than
A - ny
N - egligible
E - xtraneptunian
T - errain

?

The classification of Pluto as non-planetary doesnt bother THAT much....I'd rather it WERE a planet...however..

What bothers me is the crap defintion "clear its neigborhood" - that's utter nonsense, NO planet has cleared its neigborhood. It renders the entire planetary description as pointless as nothing has a clear neigbourhood in this solarsystem - so as of now, I believe we have NO planets.

Sod fighting for pluto....we're fighting for EARTH, Jupiter...ALL OF THEM.

Seriously - take out the 'neigborhood' clause - and I'm happy.

Doug

I fully understand Alan is hungry, but, apart historic/cultural reasons, scientifically the Pluto privileges are hardly defendible... Alan's objection about "neighborhood clearing" do not consider that NEO and trojans are less than 1/1000 the size of Earth and Jupiter, respectively!
Pls, do not hate/heat me for this observation inside a pro-Pluto thread...

Did he skip breakfast? That might make him angry

Chris

Dust is 1/1,000,000,000ths the size of my office - but I wouldn't say my office is clean

Doug

Which begs the question I have yet to get a straight answer to: why are so many astronomers (and maybe layfolk too) so keen to restrict the number of planets to a select few and what is the rationale behind it?

Even those in favour of including Pluto seem less than keen to widen the definition too far. Astronomers at the conference might have quibbled over whether there should be eight, nine or a dozen, but most if not all seemed to want some kind of cap.

Yet these same astronomers seem quite happy to accept that the terms "moon", "star", and "galaxy" should have no such limit. If there can be dozens of moons in the Solar System why can't that same solar system have dozens of planets?

What is the rationale for restricting the number of planets?

======
Stephen

I skipped my breakfast, for sure!
Doug, about neghbord clearing you know what I meant... otherwise, I will issue a "Fight for Ceres!" campaign.

Truth be told - I think we should be fighting for Ceres. It's a planet - it's a world - it's round, it's got features. Just because it lives with a few friends...it's not a planet? Thats stupid!!

A cow is a cow if it's in a field....or in a field with 20 goats.

Doug

(PS - Dilo - no, I thought I did get what you meant with your neigborhood comment, but clearly I have it wrong. There is no part of the solar system that can be considered a clean neigbourhood )

The two results I was hoping for were either a definition with eight planets or one with lots. I think the most reasonable thing for everyone, though, would be having dwarf planets count as planets. I can't think of anything else where being called an 'dwarf x' can preclude being 'x'.

I also can't see why having lots of planets is a problem for people to remember.. you're only able to remember ~10 things? Just remember the classical planets. I don't think anyone is expecting schoolchildren to start memorizing every 400+ km object in the Kuiper Belt... but I'm sure I'd have fun doing it.

Ok then, for "Star" there is:
Brown Dwarfs
White Dwarfs
Main Sequence
Sub Giants
Giants
Bright Giants
Super Giants
Along with spectral class {O,B,A,F,G,K,M}

And its worse for Galaxies!!

so "Dwarf Planet" is fine.

Nick

Too many of the elements in the IAU's definition are inherently flawed. Curiously that includes the very one that many people may have the least problem with: ""A planet is a celestial body that (a) is in orbit around the Sun".

Just exactly how do you determine that body goes round the Sun? In many cases the answer is doubtless obvious. However, as with so much else in the universe there are always exceptions. One particularly bizarre example of such an exception is object J002E3, which paid a visit to our vicinity a few years ago. It is believed to be the spent 3rd stage of one of the Apollo missions. Its orbit is such that although it usually goes round the Sun it can perodically be captured by the Earth, orbit it for a while, then escape back into solar orbit again.

A more pertinent example of an exception, though, is Earth's own Moon. Apparently the Sun's gravitation field has a stronger pull on the Moon than the Earth's own field. (For more check out here and here; for a more explicitly worked out version of the maths check out here; and there's an interesting discussion of the problem, together with lots of maths, here; while this page puts a more democratic perspective on the issue: "the moon co-orbits the sun with the earth".)

Since the IAU chose not to define the yardstick(s) on which it determines when a body is in orbit around the Sun (and when it isn't), there seems no reason the balance of gravitation forces could not be used as that yardstick. Yet were that yardstick applied to the Moon it could be used as the basis for arguing that since the Sun has a stronger pull on the Moon than the Earth's own gravitation field, the Moon is therefore (technically) in effect going round the Sun rather than around the Earth and thus (technically) not a moon under the IAU resolution but either a planet or a dwarf planet (depending on the other elements in the definitions).

======
Stephen

OK, from the top.

1) "Brown dwarfs"

Brown dwarfs are (at best) seen as failed stars, not stars per se. They are not massive enough for their thermonuclear furnaces to have ignited. (See this Wikipedia page, which dubs them "sub-stellar objects".)

2) "White Dwarfs" "Main Sequence", "Sub Giants", "Giants", "Bright Giants", "Super Giants". Not mention all those spectral classes.

All these are subcategories of stars. That is, subsets of the objects termed "stars".

By contrast, under the IAU's definition a "dwarf planet" is not a kind of "planet". Under the IAU's definition "dwarf planet" and "planet" are different species of astronomical object.

3) Ditto for galaxies. Spiral galaxies and elliptical galaxies, for example, are all classed as galaxies, rather than as objects different to galaxies.


IMHO the IAU is going to rue the day it dubbed it's second-best category "dwarf planet". Too many of us lay people are going to mistakenly think that "dwarf planet" is a kind of "planet" rather than a different category of object. Presumably the term was a bone tossed to the Pluto crowd to keep them quiet.

======
Stephen

The unfortunate wording was selected to make the text clearer to a layman. It's up to the IAU to decide what the orbital clearing means. According to them, all the eight planets have cleared their neighborhoods, whereas Ceres, Pluto, and 2003 UB313 haven't.

Back to polls (Sky & Telescope):

Complete BULL. I'd have thought SL9 or Tunguska would have reminded us all that clearing is an ongoing process for every 'planet' in the solar system.

Their definition is very very very badly written. Take out the 'cleared' tag, and you make it just about acceptable.

Doug

I thought they were scientists, scientifically superseding a fluffy floppy cultural-historical definition with a rigorous, technical scientific definition!

I have no problems with the "orbital dominance" (except for the horrible wording). Why? The IAU decided what is a planet, which is a primarily cultural term. It's more important for non-astronomers. They couldn't fathom the idea of dozens of planets. That's why the number of planets must be limited. Pluto posed a major problem, because it clearly was a member of population of many similar objects. There had to be a way to get it demoted.

Many of you actually think about non-satellite planetary mass objects, which is IMHO a completely different thing, actually. I think it would be wisest to limit the use of planet in non-scientific text and start to use the term "planemo" (or whatever) to refer any round object that does not fuse.

Phil Plait explains this much better:

The whole "neighborhood clearing" issue is bizarre. There are two ways a world can clear its neighborhood: By collision, and by ejecting smaller competitors. It's obvious that ejection, to the extent that it does proceed, take a long time. It's like a radioactive decay of the objects in crossing orbits, but the number doesn't go to zero even after eons. And there are ways that an object can actually attract crossing objects, in the Lagrangian positions, and in 3:2 resonances, etc.

Collision and ejection both take place at a rate determined in part by the mass of the object (collision also pertains to its radius). So this part of the definition is just a muddled attempt to make mass a criterion. Beyond which, it's ridiculous to suggest that Saturn only "became" a planet when it had sufficienly cleared its space. I think if you turn the clock back to the time when Saturn had hundreds of smaller bodies orbiting the Sun in its vicinity, you'd have a hard time looking at that massive globe and saying it's not a planet.

There's also attracting small bodies into its orbit, but perhaps this doesn't count as "clearing". Jupiter and Saturn travel around cloaked in immense clouds of former "competitors".

Jupiter: "Dangit, I was just about to become a planet, but then stupid SL9 comes along. Do you know how long it's going to take me to clear this up?"

advice: this post is OT here! sorry for this...

Stephen, I must confess that I ignored that ratio between the gravity force from Earth and from Sun is below 1 only for our moon!
Your links are very interesting and, apparently, all figures are right but... while math is right, there is a big flaw in the physics of all of them!
In fact, they forget that Earth-Moon system is not inertial! You cannot ignore that the Earth-Moon baricenter is moving in a circular trajectory, so there are other forces that must be considered in the game, especially the centrifugal force, which is equal to Sun gravity in the baricenter (but, obviously, points in the opposite direction).
The proof of how wrong are conclusions arising from application of inertial rules to such a rotating system is the question posed in the math forum you posted: the asking guy calculated that the equilibrium point between Sun and Earth gravity is about 258000 Km from Earth, so he wonder how the Moon can still orbiting the Earth from a larger distance.
But it is well known that the equilibrium (Lagrange) points are located 1.5 million Km from the Earth, 6 times away and well behind Moon orbit. This result can be ontained only considerning also centrifugal force arising from the rotation around the Sun.
In conclusion, when two body are gravitationally linked (and Earth-Moon are linked without any doubt), you must first consider their movement around their common baricenter and, before to consider Sun attraction, you must subctract the motion of the baricenter around the Sun. All residual forces are very small and can be considered tidal forces or second-order rotational effects...

Radicalized pro-Plutonians may find this site amusing, or at least consoling.

David,

these are priceless gems

thank you.

in the meantime I have been working to integrate the "Fight for Pluto" campaign into my extensive public outreach efforts. Your contribution will help.

ken

Sweet! I found a few that would work for my office door. I especially like the "this girl is crying because she was just told that Pluto is no longer a planet. What next? No Santa Clause?" one.

I count 4--I repeat: at least 4--of these use Ganymede as a generic icy world to represent Pluto. Now which planetary system ought we to be exploring?

The more informed you are, the more you realise Pluto is a KBO. No wonder they used Ganymede

This statment is not true for many scientists and astronomers.

Here is a link to an article on space.com titled:

300 Astronomers Will Not Use New Planet Definition
Author Robert Roy Britt
http://www.livescience.com/blogs/2006/08/3...net-definition/

More than 300 astronomers have signed a petition denouncing the IAU’s new planet definition that demotes Pluto. The petition states simply:

“We, as planetary scientists and astronomers, do not agree with the IAU’s definition of a planet, nor will we use it. A better definition is needed”

and another from NASAWATCH on 1 Sep:
http://www.spaceref.com/news/viewpr.html?pid=20725

Planet Definition by IAU Under Attack
Planetary Scientists and Astronomers Oppose New Planet Definition, Planetary Science Institute

"This petition gives substantial weight to the argument that the IAU definition of planet does not meet fundamental scientific standards and should be set aside," states petition organizer Dr. Mark Sykes, Director of the Planetary Science Institute in Tucson, Arizona. "A more open process, involving a broader cross section of the community engaged in planetary studies of our own solar system and others should be undertaken."

another quote from Dr. Mark Syskes : "I believe more planetary experts signed the petition than were involved in the vote on the IAU's petition."

At my upcoming science outreach events I will be circulating petitions for the public and scientists to sign if they wish as part of the campaign to restore Pluto to Full Planetary Status! Starting on Sep 12 in Princeton. Details will be posted soon.

ken

If I were a US scientist I would put forward a petition that the search for the real trans-neptunian planet should be better funded. But I am not. So I will just observe and sigh that a jupiter or neptune may still be lurking in the "no man's land" between the Kuiper Belt and Oort Cloud while the leading scientific community prefers to cry over spilled milk of the closer trans-neptunian regions. I also do not like the IAU definition - not because of demoting Pluto but because of adding the annoying stretch of "dwarf planets" to pretend to save if from demotion. But I am not going to argue about it any further with anyone, I only put it here as my personal view.

Here is a news article from CNN about an actual protest (withg signs!) on the decision to demote Pluto.

http://www.cnn.com/2006/TECH/space/09/02/p...t.ap/index.html

Even the California Legislature is now weighing in on this issue:

http://www.leginfo.ca.gov/pub/bill/asm/ab_..._introduced.pdf

Very nice read. Would be great if it passes, though there really is no teeth to it. Just condemns the IAU for its action. Though the wording has to make this the best piece of legislation I have ever read: