The Pluto Issue

[Cabal]

Beings as Paul says that some people who call themselves sapiens will end up becoming atheists, and change the glory of God's creation into that of corruptible man (Hermes, Zeus, the Titans, etc.), I can understand how you guys must feel.

Grow up.

Shall we just rename everything in the solar system to "Jesus", would that make you happy?

 

[Spacewyrm]

Thank you, Laurele, but I was just joking.

I don't even have any Lincoln Logs or Trivia Pursuit game.

And you made a good point too, in that I would be expunging any heritage of Pluto existing as a planet.

For the record, I still consider Pluto our 9th planet, despite what the IAU says about it.

Well, I say that Pluto is still our 13th planet; Or do you automatically accept that Vesta, Juno, Ceres, and Pallas are just asteroids just because some people behind a clipboard decided that in the 1800's.

 

[AV1611VET]

Well, I say that Pluto is still our 13th planet; Or do you automatically accept that Vesta, Juno, Ceres, and Pallas are just asteroids just because some people behind a clipboard decided that in the 1800's.

Vesta, Juno, Ceres, and Pallas can take a hike.

 

[Spacewyrm]

Vesta, Juno, Ceres, and Pallas can take a hike.

Pluto: "When they told Vesta, Juno, Ceres, and Pallas to take I hike, I said nothing, 'cause I'm not in the Asteroid Belt. When they told me to take a hike, there was noone there to stand up for me."

 

[laurele]

Thank you, Laurele, but I was just joking.

I don't even have any Lincoln Logs or Trivia Pursuit game.

And you made a good point too, in that I would be expunging any heritage of Pluto existing as a planet.

For the record, I still consider Pluto our 9th planet, despite what the IAU says about it.

I'm so glad to hear this was only a joke!

 

[Split Rock]

I'm still at a loss AV, I'm sorry.

Yes, some people weren't happy with the decision, but I still fail to see a) what the problem is, and b) why this refers to science. It was pretty much an aesthetic decision.

I am a bit late to this discussion, but I wanted to address the claim that renaming Pluto was just an "aesthetic issue" and our understanding or Pluto never changed. I am not an astronomer, but I may know more about the subject than most here. I don't think we have any actual astronomers here, unfortunately.

When Pluto was discovered there were some odd things about its makeup and orbit that were discovered rather quickly. One: It is a ball of ice, not a gas giant (all the other outer planets were gas giants). This made it more like a comet than a planet, albet a large one. Two: Its orbit was highly eliptical and eccentric (out of plane) compared to all the other planets. At the time, the definition of "planet" was rather vague, and there really wasn't any other name for Pluto... it was a large circular body in orbit around the sun, and that was good enough, even though it was rather odd compared with the other planets.

Later, as Psudopod indicated, other bodies were discovered that would also need to be called "planet" if Pluto were one. So, what's the problem with this (Doveaman asked this question)? The developmental process for planets and comet-like objects are likely very different. If they are different in makeup and how they form, they should probably be categorized differently. This was another reason to "demote" Pluto from the Planet category, other than the issue of having many more planets than just 9 or 10.

So, there were two major reasons for the name change:

1. The term "planet" was poorly defined in the first place and Pluto didn't fit the new term.
2. Pluto didn't really fit in with the other planets, but was much more like comet-like bodies found in the Kuiper belt .

So, I think it was more than just for "aesthetics" that Pluto was removed from the list of Planets.

 

[Split Rock]

Thank you. I will admit I'm not a PhD, but I am an amateur astronomer and a student in the Masters in astronomy program at Swinburne University.

Planetary science does involve chemistry, geology and biology (at least when in studying Earth), so scientists interested in this field should know something about each of these. One of the issues with the IAU vote is that most who voted are not planetary scientists but other types of astronomers entirely, ones who study galaxies, black holes, dark matter, cosmology, radio astronomy, etc. This means those who decided on the new definition are largely people who do not study planets! Planetary science, especially as it concerns objects beyond Earth, is a relatively new science, having benefitted heavily from our robotic explorations of the moon and solar system over the last 50 years. Many planetary scientists are not IAU members and therefore have no say about definition of terms in their own field. There is some talk about forming a separate planetary society organization, but it has not yet been done. The field is still considered by many to be in its infancy.

Glad to see an astronomer here!

Don't you think that the developmental processes for the eight planets was different from Kuiper belt objects like Pluto? If so, shouldn't Pluto be categorized with other Kuiper belt objects? It seems to me that all because an object is large enough in mass to round itself during its formation, doesn't necessarily mean that it should be in the same category as other such objects that have a different developmental history. What are your thoughts on this?

 

[Split Rock]

Excellent post, laurele!

I was hoping a real astronomer would show up and say something.

I am also happy to see an astronomer here to discuss the issue.

I get tired of armchair astronomers arguing this point.

Kind of like armchair biologists and geologists telling the people who did this science for a living what is wrong with evolution or what the age of the planet really is.

In reality, AVET, we have been arguing with you not on whether or not Pluto should be called a Planet or a Dwarf Planet, or something else, but what the significance of the IAU decision really was, especially in terms of the reliability of science in helping us understand nature.

I don't know much science myself, but I get suspicious when a biologist starts talking about plate tectonics, or a geologist talks about biology.

When I discuss matters outside my own field, I rely on what experts in that field say, along with my own limited knowledge in that field. Most of the time here, we are stamping out misrepresentations of what the professionals in those fields actually say, which doesn't require as much technical understanding anyway.

It just doesn't set right with me; and it comes across as an attitude of 'Since I have a PhD in chemistry, I'm qualified to talk about astronomy.'

How about, "since I am a self-proclaimed expert in Bible interpretation I'll tell you scientists what you are doing wrong?"

 

[laurele]

Glad to see an astronomer here!

Don't you think that the developmental processes for the eight planets was different from Kuiper belt objects like Pluto? If so, shouldn't Pluto be categorized with other Kuiper belt objects? It seems to me that all because an object is large enough in mass to round itself during its formation, doesn't necessarily mean that it should be in the same category as other such objects that have a different developmental history. What are your thoughts on this?

We are still learning about the developmental processes of planets. So many strange exoplanets have been discovered that much of what we thought we knew has beencalled into question. Can we really say that gas giants like Jupiter have the same formation process as terrestrial planets like Earth? The composition of gas giants is far more like that of the Sun. Objects currently in the Kuiper Belt did not necessarily start out there. Neptune itself is believed to have formed closer to the Sun and migrated outward. There are similarities in the formation of Pluto and other dwarf planets with the formation of terrestrial planets, as they all ended up geologically differentiated, as did some of the larger moons of the outer planets. While can we not classify Pluto dually as both a planet and a Kuiper Belt Object? It may not be in the same category as Earth or Jupiter, but that does not mean it is not a planet. We can look to the precedent of dwarf stars and dwarf galaxies. Dwarf stars are much smaller than other types of stars, but they are still classified as stars. Dwarf galaxies often do not have the recognized spiral shape and can be tiny compared to big galaxies like the Milky Way. Similarly, dwarf planets are simply another category of planets. It is just as important to differentiate Pluto from most other Kuiper Belt Objects because they do not have the planet like features Pluto has and are much, much smaller. It's fine to say that not all objects large enough to be pulled into a round shape by their own gravity should be lumped into one category, but that does not mean we cannot recognize the similarities due to their being in hydrostatic equilibrium and then differentiate the different types through use of subcategories.

 

[laurele]

I am a bit late to this discussion, but I wanted to address the claim that renaming Pluto was just an "aesthetic issue" and our understanding or Pluto never changed. I am not an astronomer, but I may know more about the subject than most here. I don't think we have any actual astronomers here, unfortunately.

When Pluto was discovered there were some odd things about its makeup and orbit that were discovered rather quickly. One: It is a ball of ice, not a gas giant (all the other outer planets were gas giants). This made it more like a comet than a planet, albet a large one. Two: Its orbit was highly eliptical and eccentric (out of plane) compared to all the other planets. At the time, the definition of "planet" was rather vague, and there really wasn't any other name for Pluto... it was a large circular body in orbit around the sun, and that was good enough, even though it was rather odd compared with the other planets.

Later, as Psudopod indicated, other bodies were discovered that would also need to be called "planet" if Pluto were one. So, what's the problem with this (Doveaman asked this question)? The developmental process for planets and comet-like objects are likely very different. If they are different in makeup and how they form, they should probably be categorized differently. This was another reason to "demote" Pluto from the Planet category, other than the issue of having many more planets than just 9 or 10.

So, there were two major reasons for the name change:

1. The term "planet" was poorly defined in the first place and Pluto didn't fit the new term.
2. Pluto didn't really fit in with the other planets, but was much more like comet-like bodies found in the Kuiper belt .

So, I think it was more than just for "aesthetics" that Pluto was removed from the list of Planets.

First, amateur astronomers are astronomers too. Some of the so-called amateurs in my astronomy club are more knowledgable in the field than some professionals.

The issue is not just aesthetic and not even just semantics. It has to do with blurring the distinction between objects that are very different--in other words, between asteroids and comets on the one hand and planets on the other. It has to do with a flawed definition whose terms can never be pinned down (how does one determine whether an object fully clears its orbit?) and a linguistic impossibility that claims dwarf planets are not planets. Something does not become "truth" just because a small group, even one of PhDs, determined it to be so. There is a serious problem with the attempt by this small group to impose its definition as "fact" when it is really nothing more than one interpretation.

Pluto is not just a "ball of ice." It is estimated to be 75 percent rock, something not true of comets. Its orbit is elliptical, but so is Mercury's. And many exoplanets more massive than Jupiter have orbits far more elliptical than Pluto's. Does this mean they are not planets? One can seriously question the statement that Pluto's developmental process is more akin to that of comets than planets. Not a single comet is geologically differentiated. The largest comet known is Chiron, actually classified as a centaur (a combination of asteroid and comet), which is 113 miles in diameter. Pluto is over 1400 miles in diameter. Its orbit never takes it into the inner solar system. Comets eventually break up because with each passage near the Sun, the ice sublimates, forming the tail. Meteor showers are the remnants of comets that have completely broken up. Pluto never experiences such mass loss.

The argument that "we cannot have too many planets" has no scientific basis whatsoever. No one argues that we cannot have billions of stars or billions of galaxies. The real paradigm shift here is from a solar system with a small, countable number of planets to one with potentially hundreds of planets. Most of these likely fall into the dwarf planet category. However, that does not make them not planets. And memorization is not a very important tool in learning anyway. It is far more important for kids to understand the concepts of the different types of planets, i.e., what makes a planet a gas giant, what are the characteristics of each type of planet, etc.

 

[Cabal]

I'm surprised no-one's mentioned formation from the same accretion disk yet. Pluto's orbit certainly makes it look like it just wandered in from a random angle one day.

 

[Doveaman]

We are still learning about the developmental processes of planets. So many strange exoplanets have been discovered that much of what we thought we knew has beencalled into question.

I think I have an idea why.

 

[Split Rock]

We are still learning about the developmental processes of planets. So many strange exoplanets have been discovered that much of what we thought we knew has beencalled into question. Can we really say that gas giants like Jupiter have the same formation process as terrestrial planets like Earth? The composition of gas giants is far more like that of the Sun. Objects currently in the Kuiper Belt did not necessarily start out there. Neptune itself is believed to have formed closer to the Sun and migrated outward. There are similarities in the formation of Pluto and other dwarf planets with the formation of terrestrial planets, as they all ended up geologically differentiated, as did some of the larger moons of the outer planets. While can we not classify Pluto dually as both a planet and a Kuiper Belt Object? It may not be in the same category as Earth or Jupiter, but that does not mean it is not a planet. We can look to the precedent of dwarf stars and dwarf galaxies. Dwarf stars are much smaller than other types of stars, but they are still classified as stars. Dwarf galaxies often do not have the recognized spiral shape and can be tiny compared to big galaxies like the Milky Way. Similarly, dwarf planets are simply another category of planets. It is just as important to differentiate Pluto from most other Kuiper Belt Objects because they do not have the planet like features Pluto has and are much, much smaller. It's fine to say that not all objects large enough to be pulled into a round shape by their own gravity should be lumped into one category, but that does not mean we cannot recognize the similarities due to their being in hydrostatic equilibrium and then differentiate the different types through use of subcategories.

You bring up some good points. I agree that calling Pluto a "dwarf planet" but not a type of planet makes no sense and sets a poor precident. What you also said about the fact we have many other solar systems to study now also rings true... what we know about planet formation (or think we do) will likely require many changes. It may make more sense to simply categorize objects by whether or not they are in "hydrostatic equilibrium" (a new term for me!) and then subcategorize them to differentiate objects like Uranus from Kuiper Belt objects.

First, amateur astronomers are astronomers too. Some of the so-called amateurs in my astronomy club are more knowledgable in the field than some professionals.

Please do not take insult... I wrote that before really reading your posts. I do consider you to be an "astronomer," which is why I am pleased you have joined in teh discussion.

The issue is not just aesthetic and not even just semantics. It has to do with blurring the distinction between objects that are very different--in other words, between asteroids and comets on the one hand and planets on the other. It has to do with a flawed definition whose terms can never be pinned down (how does one determine whether an object fully clears its orbit?) and a linguistic impossibility that claims dwarf planets are not planets. Something does not become "truth" just because a small group, even one of PhDs, determined it to be so. There is a serious problem with the attempt by this small group to impose its definition as "fact" when it is really nothing more than one interpretation.

I agree that "fully cleared its orbit" is a poor definition to pin terminology on. The whole decision, especially calling Pluto a "dwarf planet," but not a "planet," rings of an attempt at compromise. Compromise is often good, but not always.

As far as the legallity of the IAU decision, that is something the IAU will need to iron out. The decision only affects the IAU, or course, unless it is widely adapted by thoses doing research in planetary astronomy. You seem to be implying that many, if not most such researchers are likely to reject the new terminology. If that is the case, then the IAU will eventually need to revisit this issue. Otherwise, they risk losing credibility, as well as usefulness to the researchers they are supposed to represent.

Pluto is not just a "ball of ice." It is estimated to be 75 percent rock, something not true of comets. Its orbit is elliptical, but so is Mercury's. And many exoplanets more massive than Jupiter have orbits far more elliptical than Pluto's. Does this mean they are not planets? One can seriously question the statement that Pluto's developmental process is more akin to that of comets than planets. Not a single comet is geologically differentiated. The largest comet known is Chiron, actually classified as a centaur (a combination of asteroid and comet), which is 113 miles in diameter. Pluto is over 1400 miles in diameter. Its orbit never takes it into the inner solar system. Comets eventually break up because with each passage near the Sun, the ice sublimates, forming the tail. Meteor showers are the remnants of comets that have completely broken up. Pluto never experiences such mass loss.

I was unaware that Pluto is mostly rock... thanks for the info. The orbit, however, is not only highly elliptical (all planetary orbits are in reality elliptical, as none are perfect circles) but it is also greatly inclined from the plane of the solar system. This certainly implies it did not form the same way as the other planets.

The argument that "we cannot have too many planets" has no scientific basis whatsoever. No one argues that we cannot have billions of stars or billions of galaxies. The real paradigm shift here is from a solar system with a small, countable number of planets to one with potentially hundreds of planets. Most of these likely fall into the dwarf planet category. However, that does not make them not planets. And memorization is not a very important tool in learning anyway. It is far more important for kids to understand the concepts of the different types of planets, i.e., what makes a planet a gas giant, what are the characteristics of each type of planet, etc.

All true. The idea of a countable number of "planets" I suspect is as ingrained as learning that Pluto is a "planet." Neither is a good argument to keep outdated terminology.

I think you have made some good points. Personally, I think it would be fine to call Pluto a "planet" and differentiate it as a "dwarf planet" (keep in mind I have little personal stake in this). I suspect a definition will eventually be agreed upon by those who really define these terms.. those doing the research.

I'm surprised no-one's mentioned formation from the same accretion disk yet. Pluto's orbit certainly makes it look like it just wandered in from a random angle one day.

Covered!

 

[Beechwell]

Ok, I know this is already a bit of a necro. But I just read a rather interesting article (here - it's in German, though) about the history of Pluto's discovery.
The article suggests that the anger over the "degradation" of Pluto is mostly a matter of hurt American pride. Pluto is/was the only planet discovered by a US-American. And Clyde Tombaugh, the discoverer became a bit of an American hero (according to the article - please correct if wrong), a role he would have fit quite well as a hard-working member of the common people (and not an aloof college graduate). So the recent degradation of Pluto to a dwarf-planet also implicitly degraded the work of the hero Tombaugh.
That would explain why the agitation about Pluto's degradation is mostly an American phenomenon. Here in Europe people may have been a little irritated, but noone considered it a big issue; it was hardly ever mentioned at the Institute for Astrophysics where I wrote my degree dissertation at that time.
Certainly noone over here went into the streets to protest for a smallish lump of rock in the Cuiper belt.

So, what do you people think? Is the discontent about the IAU's decision a matter of hurt national feelings? Or more generally speaking, is it an emotional cause, or a scientific one?

 

[Chesterton]

So, what do you people think? Is the discontent about the IAU's decision a matter of hurt national feelings? Or more generally speaking, is it an emotional cause, or a scientific one?

I disagree with the pride thing. Classifying it differently doesn't detract at all from the discovery.

 

[Beechwell]

I disagree with the pride thing. Classifying it differently doesn't detract at all from the discovery.

Objectively not, that is true. But emotionally I think it could.
Actually I don't understand why people get so emotionally involved in the issue at all (as seen in this very thread). I'm just trying to find an explanation for that.
Or maybe it is merely a symptom of struggles within the community of astronomers, concerning the role of the IAU? I don't know.

 

[Split Rock]

Objectively not, that is true. But emotionally I think it could.
Actually I don't understand why people get so emotionally involved in the issue at all (as seen in this very thread). I'm just trying to find an explanation for that.
Or maybe it is merely a symptom of struggles within the community of astronomers, concerning the role of the IAU? I don't know.

I agree there seems to be a lot of emotion involved. Not accepting a new defintion of "planet" should not be based on "that's the way I learned it in school." Also, I find it bizarre that there are state legislatures in the U.S. that have nothing better to do with their time than to pass legislation on preserving Pluto as a "Planet."

 

[ArnautDaniel]

Ok, I know this is already a bit of a necro. But I just read a rather interesting article (here - it's in German, though) about the history of Pluto's discovery.
The article suggests that the anger over the "degradation" of Pluto is mostly a matter of hurt American pride. Pluto is/was the only planet discovered by a US-American. And Clyde Tombaugh, the discoverer became a bit of an American hero (according to the article - please correct if wrong), a role he would have fit quite well as a hard-working member of the common people (and not an aloof college graduate). So the recent degradation of Pluto to a dwarf-planet also implicitly degraded the work of the hero Tombaugh.
That would explain why the agitation about Pluto's degradation is mostly an American phenomenon. Here in Europe people may have been a little irritated, but noone considered it a big issue; it was hardly ever mentioned at the Institute for Astrophysics where I wrote my degree dissertation at that time.
Certainly noone over here went into the streets to protest for a smallish lump of rock in the Cuiper belt.

So, what do you people think? Is the discontent about the IAU's decision a matter of hurt national feelings? Or more generally speaking, is it an emotional cause, or a scientific one?

The main problem with this is that the vast majority of Americans have never heard of this guy and it would be news to them that an American had discovered Pluto.

I think it has more to do with the 9 planets being one of those things you learn very early on in your education.

 

[Beechwell]

The main problem with this is that the vast majority of Americans have never heard of this guy and it would be news to them that an American had discovered Pluto.

Ok, that is admittedly an Achilles' Heel of that theory. Although it may still be possible that Pluto still implicitly has a different, more important status in the US than in Europe becuase of this.

I think it has more to do with the 9 planets being one of those things you learn very early on in your education.

That doesn't explain the different reaction in the US as opposed to Europe. But maybe that is due to lon-linear (chaotic) social dynamics, and without deeper reason.

 

[ArnautDaniel]

Ok, that is admittedly an Achilles' Heel of that theory. Although it may still be possible that Pluto still implicitly has a different, more important status in the US than in Europe becuase of this.

That doesn't explain the different reaction in the US as opposed to Europe. But maybe that is due to lon-linear (chaotic) social dynamics, and without deeper reason.

More Americans also disbelieve in evolution than do Europeans.

There is a cultural trait, but I think the Pluto thing is just one of many symptoms of something more general.