I've been thinking about The Pluto Files on PBS and Pluto's demotion for a month

[pschroeter]

Ever since PBS ran The Pluto Files last month I have been trying to wrap my mind around the reason that Pluto was “demoted” from planet status. I have been thinking about the new definition of dwarf planet and it seems to me to boil down to the part of the definition that says something about the ability to "clear the neighborhood around their orbits." I ask “so what?" What is so critical about this distinction?

It seems to me that after the they discovered Eris astronomers were uncomfortable with idea of all the possible planets they might find in the Kuiper belt. What do they have against the Kuiper belt?

As a matter of semantics, “dwarf planet” still has the word “planet” in it. Doesn’t this make it a planet, subcategory dwarf? Jupiter is a big ball of gas. I think it is a failed star. Pluto is round and I could go there and put on a space suit and walk around on it.

I think the IAU is making a fine distinction that most people outside the IAU are not going to get, and therefore to most regular people does not seem necessary.

The Pluto Files—which I enjoyed and watched twice—claimed Pluto was the most popular planet, I don’t know where they got this. My vote goes to Mars.

Edit April 5
After reading some of the replies I notice a lot of people take issue with my use of the word "demoted." At first I was going to say it was a poor choice of words, I meant reclassification, but I now realize I am correct. Here why. I have two Almanacs, one from 1998 and a more recent one by the exact same company from 2007. In the 1998 one Pluto gets it own little section at the end of the group of articles for each planet. All planets are discussed equally in terms of characteristics and such. In the 2007 one, it is mentioned in a short section on the new dwarf planets which also mentions how Pluto use to be a planet. I have a recent astronomy book and Pluto is no longer listed at the end of table of characteristics of planets of the solar system section that most books like it have. I will have to look up its size, distance from the sun and ect. somewhere else. It has been demoted.

I don't have an emotional reason to keep Pluto a planet. I just find the whole issue fairly complicated and funny. I still don't understand the "clear the neighborhood around their orbits" requirement and why it makes such a big difference.

[George]

What is so critical about this distinction?

It seemed to be the best way to get Pluto demoted.

It seems to me that after the they discovered Eris astronomers were uncomfortable with idea of all the possible planets they might find in the Kuiper belt. What do they have against the Kuiper belt?

They like the Kuiper Belt. The current count, however, of KBOs is something like 1000 objects and many have moons revolving around them, like Pluto. There could be several hundred "planets" out there and that diminishes the common view of planets.

I think the IAU is making a fine distinction that most people outside the IAU are not going to get, and therefore to most regular people does not seem necessary.

The problem is probably the amount of heart that is associated with Pluto, especially thanks to Disney. If it had a name like, oh say... George, it would get booted-out even if the discoverer so name it.

The Pluto Files—which I enjoyed and watched twice—claimed Pluto was the most popular planet, I don’t know where they got this. My vote goes to Mars.

Kids must have been in the survey. I still get tickled when I think about Neil Tyson's shocked face when he described what it was like (as an astrophysicst) to "get hate mail from 3rd graders".

[Kinetic]

I never found the demotion of Pluto to be too much of a problem given that it's unlike the rest of the terrestrial planets in terms of mass/density/orbit etc. If it was a unique Kuiper Belt object I think a case could be made for it but as it stands it looks like it's just one of many 'large' bodies past Neptune.

[Gillianren]

Jupiter is a big ball of gas. I think it is a failed star.

No offense, but so what? The question is, do astronomers think it's a failed star? Frankly, their opinion matters more than the general public's. There are a lot of astronomical distinctions the general public doesn't get, and the IAU doesn't have to cater to all of them.

Though honestly, I don't care one way or the other on the subject of Pluto's planetary status.

[grant hutchison]

Pluto wasn't "demoted". No-one pulled the insignia off its uniform, tore up its commission, and sent it humiliated back to the ranks.
It was reclassified.

Grant Hutchison

[George]

Pluto wasn't "demoted". No-one pulled the insignia off its uniform, tore up its commission, and sent it humiliated back to the ranks.
It was reclassified.

Yes, it was properly reclassified, but it was a demotion. To go from being the 9th planet to a dwarf planet is similar to going from president to vice-president. The term "dwarf" only exacerbates this fact, and to many people "planet" is a special title of celestial worth.

I am curious whether or not this is more an American issue, partly due to it being the only "planet" discovered here, as well as, all the Disney influence in the Pluto name?

[grant hutchison]

Yes, it was properly reclassified, but it was a demotion.

Why? Does it get paid any less? Does it have fewer responsibilities? Do people respect it less?
(It seems to me that the only people who respect Pluto less because of this reclassification are the ones who are making the "demotion" fuss; and that's perhaps an issue for a psychologist rather than the IAU. The rest of us aren't bothered because nothing about Pluto has changed.)

Grant Hutchison

[Van Rijn]

Yes, it was properly reclassified, but it was a demotion. To go from being the 9th planet to a dwarf planet is similar to going from president to vice-president. The term "dwarf" only exacerbates this fact, and to many people "planet" is a special title of celestial worth.

I have to agree. Pluto used to be considered one of nine planets. Now it is an ex-planet, a dwarf planet, one of many TNOs, and not the largest TNO.

Granted, it is an inanimate object, but it has been demoted by the evidence and by the "dwarf planet" classification. Note that I don't have a big emotional concern about it, but I would certainly consider it a demotion.

[WayneFrancis]

Yes, it was properly reclassified, but it was a demotion. To go from being the 9th planet to a dwarf planet is similar to going from president to vice-president. The term "dwarf" only exacerbates this fact, and to many people "planet" is a special title of celestial worth.

I am curious whether or not this is more an American issue, partly due to it being the only "planet" discovered here, as well as, all the Disney influence in the Pluto name?

You are implying that "dwarf" is a derogatory term? It is a descriptive term. Does the term "Giant" in "Gas Giant" make it a better class of planet then a "Terrestrial planet"? I mean if you are fixated on terms that relate to size and "dwarf" is bad then surely "Giant" is good and there for Jupiter and Saturn must be the greatest.

[grapes]

Why? Does it get paid any less? Does it have fewer responsibilities? Do people respect it less?
(It seems to me that the only people who respect Pluto less because of this reclassification are the ones who are making the "demotion" fuss; and that's perhaps an issue for a psychologist rather than the IAU. The rest of us aren't bothered because nothing about Pluto has changed.)

Except, it doesn't appear in the IAU list of planets, a list maintained by the IAU.

So, yes it was a demotion--even though Neil Tyson would say it was promoted to King of the Kuiper Belt.

Tyson's explanation from nine years ago did not require changing the list of planets.

[Daggerstab]

Why nobody seems to care about Ceres' promotion?

I am curious whether or not this is more an American issue, partly due to it being the only "planet" discovered here, as well as, all the Disney influence in the Pluto name?

Yes, I've wondered about the same thing.

Pluto's name may sound cute and cuddly in English, but the Bulgarian variant does sound like the name of a god of the underworld, so it's a bit awkward to say "poor Pluto".

[George]

Why? Does it get paid any less?

Yes, it is paid less in attention. Pluto is no longer on the varsity roster in textbooks; it's on the B team and given less mention (excluding the debate factor).

Do people respect it less?

I think they will. Consider the weight given between the news of new exoplanets vs. new dwarf exoplaners (once we can them). The former offers more potential interest for us.

(It seems to me that the only people who respect Pluto less because of this reclassification are the ones who are making the "demotion" fuss; and that's perhaps an issue for a psychologist rather than the IAU. The rest of us aren't bothered because nothing about Pluto has changed.)

I mostly agree with your view as there is much here that involves the anthropomorphic influence. I also agree with the IAU because the evidence favoring Pluto as a KBO, a large one but among thousands of others, is much greater rather than the evidence supporting Pluto being one of nine.

Tyson's explanation from nine years ago did not require changing the list of planets.

that would surprise me and I didn't find his comment in the linked page.

You are implying that "dwarf" is a derogatory term? It is a descriptive term. Does the term "Giant" in "Gas Giant" make it a better class of planet then a "Terrestrial planet"?

Is a Bengal tiger just a cat? To a distant zoologist, perhaps, but certainly not to the general public.

I mean if you are fixated on terms that relate to size and "dwarf" is bad then surely "Giant" is good and there for Jupiter and Saturn must be the greatest.

It would depend on the interests of the listener. Earth-like planets found elsewhere are likely at the front of the echelon, though the Giants imply something big and noteworthy to the average reader. Big things usually get more attention than little things. If descripitive terms are to come with no meaning other than of a sceintific nature, than perhaps giving them classifications as are given stars (O...M).

Now it is an ex-planet, a dwarf planet, one of many TNOs, and not the largest TNO.

Yes, and an ex-anything that moves out of the lime light is different than the ex-things that move into the lime light. The direction of the move carries weight to most of the public and some of the scientists, I would think. The better a scientific term is both descriptive and fits analogies humans like to make of it the better.

[grant hutchison]

Pluto's name may sound cute and cuddly in English, but the Bulgarian variant does sound like the name of a god of the underworld, so it's a bit awkward to say "poor Pluto".

It's the same in English. Pluto is still a recognized alternative name for the Greek underworld, Hades, and is also sometimes applied to the ruler of Hades. That has always made the name of the cartoon dog ridiculous for me: like calling him Satan or Beelzebub.

Grant Hutchison

[grapes]

that would surprise me and I didn't find his comment in the linked page.

He quotes the exhibit panel:

"What is a planet?"

"In our solar system, planets are the major bodies orbiting the Sun. Because we cannot yet observe other planetary systems in similar detail, a universal definition of a planet has not emerged. In general, planets are massive enough for their gravity to make them spherical, but small enough to avoid nuclear fusion in their cores."

Pluto fits that general description, of course.

It's the same in English. Pluto is still a recognized alternative name for the Greek underworld, Hades, and is also sometimes applied to the ruler of Hades. That has always made the name of the cartoon dog ridiculous for me: like calling him Satan or Beelzebub.

Except, the underworld was not the same as our hell. As this wiki on Pluto says, "Pluto was worshipped by the Romans for some of his kinder attributes."

[grant hutchison]

He quotes the exhibit panel: Pluto fits that general description, of course.Except, the underworld was not the same as our hell. As this wiki on Pluto says, "Pluto was worshipped by the Romans for some of his kinder attributes."

The worship of Pluto didn't have much to do with the underworld at all, really. He was worshipped according to his role in agriculture and wealth. In his more Hadean role, there's little evidence of him being worshipped at all.
Somehow, the fact that the God of the Underworld was worshipped in other roles doesn't seem to make the cartoon dog's name any less jarring. Perhaps that's just me.

Grant Hutchison

[Gillianren]

Somehow, the fact that the God of the Underworld was worshipped in other roles doesn't seem to make the cartoon dog's name any less jarring. Perhaps that's just me.

It may not be just you, but it certainly isn't me. And the Greeks, as mentioned, didn't have a Hell much like ours at all. You had to do something really bad to gain a punishment, and they were generally ironic in some way.

Does anyone know if this happened the first time 'round, when Ceres got demoted?

[grant hutchison]

And the Greeks, as mentioned, didn't have a Hell much like ours at all.

They did have Tartarus, which served many of the same functions as our Hell, and which was often (though admittedly not consistently) described as part of Hades. But all in all one's options do seem to have been slightly more varied in the Greek afterlife.

Grant Hutchison

[kleindoofy]

... Pluto was “demoted” ...

Please post your order of celestial body ranks.

Is the Earth lower than a "gas giant"?

Are comets officers or enlisted bodies?

I.e., I don't get it.

... Pluto is round and I could go there and put on a space suit and walk around on it. ...

Just like the Moon.

[grapes]

The worship of Pluto didn't have much to do with the underworld at all, really.

Exaclty. So, Disney has that out.

Plus, there was a nymph named Pluto, grandmother of the house of Atreus, another tantalizing story of hell.

Perhaps that's just me.

I dunno.

Do you think of hell when you hear the word plutocrat?

[grant hutchison]

Do you think of hell when you hear the word plutocrat?

Frequently. But not entirely because of the shared etymology.

Grant Hutchison

[grapes]

Frequently. But not entirely because of the shared etymology.

Wealth? Do you know the book Rich Dad, Poor Dad?

[grant hutchison]

Wealth?

Yes.

Do you know the book Rich Dad, Poor Dad?

I don't.

Grant Hutchison

[George]

Pluto fits that general description, of course.

Tyson is a great PR guy and likely was not wishing to be any more controversial, especially after getting thrashed on the front page of the NY Times. Nevertheless, he held to his guns and I agree with his view, which was made official by the IAU in Prague.

His comments about landscape and Pluto being the King of the Kuiper Belt -- I suppose Pluto has been dethroned once again due to the size of Eris (doubly dethroned?) -- is enough to tell me he would disagree, perhaps gently, with Pluto being labeled a planet by others.

[Added: BTW, I'd bet a dollar to a donut that Tyson hangs here in BAUT now and then, if not a poster. He made a comment in his last book that was a small colorful topic here at one point, having to do with the Sun, though not the true color topic.]

[grapes]

I don't.

I haven't read it either, and I wasn't familiar with the "wealth" etymology, I looked in up in my Ame.Her.Dic.--my copy of Zimmerman's Dictionary of Mythology claims that the word plutocrat comes from Plutus, or Ploutos, Greek god of wealth.

But it seems that Disney's choice was divinely inspired.

[parallaxicality]

Wow. 36 hours and Laurel hasn't posted. That's gotta be an internet record.

By the way, Hades was called "Plutus", the wealthy because, as God of the Underworld, all the gems and gold in the world belonged to him.

The IAU definition was an attempt to please everyone, and, like any attempt to please everyone, it pleased no one. Basically, it was an attempt to fuse the "dynamic" definition of planet ("a planet is an object which orbits a star and is large enough to have cleared its orbit of smaller bodies") and the "physical" definition of planet ("a planet is an object that is large enough to be round but not large enough to fuse its own matter"). Note that, in its purest form. the dynamic definition doesn't mention dwarf planets and the physical definition doesn't care if a planet orbits a star or not. If we count by the purely dynamic definition, there are 8 planets in the Solar System. If we count by the physical definition, which would include all current dwarf planets as well as 19 moons, there are 32.

The scrap over the definition of planet boils down to a trade-off: do you want a simple, easily comprehensible definition of planet that leaves you with a complicated, messy Solar System where some moons are planets and some aren't, some KBOs are planets and some aren't, and some asteroids are planets and some aren't, or do you want a complicated, messy definition of planet that leaves a lot of people scratching their heads but gives us a nice, simple Solar System where everything is in its proper place? Astronomers, who look at the Solar System as a whole, prefer the latter definition, planetary scientists, who tend to see all planet-shaped bodies individually without much care for what's surrounding them, prefer the first definition. Unfortunately, the IAU is the International Astronomical Union and it was mostly astronomers who voted. So we got a (mostly) astronomical definition with a sop thrown in for the planetary scientists, the term "dwarf planet" (which isn't a planet)

[Gillianren]

Wow. 36 hours and Laurel hasn't posted. That's gotta be an internet record.

Doubtless stemming from the board's own issues.

[grapes]

By the way, Hades was called "Plutus", the wealthy because, as God of the Underworld, all the gems and gold in the world belonged to him.

I'm confused (I know I know )

This wiki on Plutus says that "In Canto VII of Dante's Divine Comedy, Plutus (Pluto in the original Italian) is a wolf-like demon of wealth which guards the fourth circle of the Inferno, the Hoarders and the Wasters. Dante almost certainly conflated Plutus with Pluto, the Roman god of the Underworld." Literary license? D*ng Dante. And what was Aristophanes thinking? In his play Plutus? (I know Greek ain't English, but still...this has relevance as a classification problem.)

[parallaxicality]

Sorry. It was actually "Pluton", or more correctly, "Plouton", though the Greek word for wealth is "ploutos".

[korjik]

Pluto wasnt demoted from a planet, it was wrongly called a planet in the first place. It isnt a planet.

It is a KBO. An asteroid. It may be alot bigger than any of the Asteroid belt asteroids, but it is still tiny compared to Mercury.

[Disinfo Agent]

This wiki on Plutus says that [...]

There's another interesting quote in that article:

In Lucian of Samosata's satirical dialogue Timon, Ploutus, the very embodiment of worldly goods written up in a parchment will, says to Hermes:

"[...] Pluto and Plutus are not unconnected, you see. When I am to flit from one house to another, they lay me on parchment, seal me up carefully, make a parcel of me and take me round. The dead man lies in some dark corner, shrouded from the knees upward in an old sheet, with the cats fighting for possession of him, while those who have expectations wait for me in the public place, gaping as wide as young swallows that scream for their mother's return."