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Pluto? Who cares? August 29, 2006

Posted by Jorge Candeias in Definition of planet, Pluto.
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One of the things that has surprised me the most in all this debate on what is a planet is the obsession that so many people seem to have with Pluto. I expected it from people who didn’t know about the Solar System much more than the names of the “nine planets”, but the passion so many of the scientists involved, even those that qualified the whole debate as silly, seemed to have about the status of Pluto frankly amazed me. People seemed to decide first if they thought that Pluto was a planet or not and only then chose a definition for planet that placed Pluto where they thought it should be.

In reality, Pluto shouldn’t matter at all. The debate should be centered on what should be the criteria for an object to be qualified as planet regardless of what would happen to Pluto or any other planet in the Solar System or elsewhere. The questions that must be answered are not “is Pluto a planet?”, but “what is a planet?” and “is there any good difference between what’s a planet and what isn’t?” and “of all the things that could be used to set apart planets from non-planets which are the best ones?” It should be only after finding a good answer to these questions that the one about the status of Pluto (or any other planetary object, really) must be answered.

In science, prejudice should not have a place. Whenever it does find its way into scientific theories the result goes from simply wrong to disastrous. We’ve seen it happen over and over again, particularly in human studies, in theories about racial superiority, or about the intrinsic intellectual inferiority of women, or about sexual minorities. But we’ve also seen its nasty work in astronomy, and I’m not talking about those astronomers that were imprisoned or killed by other people, for defending “blasphemous” cosmological theories, for instance, such as Galileo or Copernicus: I’m talking about the astronomers that spent their entire life, or a good portion of it, trying to fit data to their particular pre-conceived ideas on how the universe should work. The great ones, such as Kepler, who spent long years trying to fit planetary movements in circular orbits due to a religious notion that the work of god should result in the perfection of the circle, managed to rise above their prejudice and abandon it at some point. The lesser ones persisted… and were forgotten.

I would like to see Pluto being put aside for a while. I would like to see people discussing the characteristics of the planets regardless of the characteristics of Pluto or its orbit. That would be good science. To decide first if Pluto is a planet or not and only then trying to find a formulation that fits is not.


1. Cbrannon - August 5, 2009


Like the blog. Glad you got it back up and running. I noticed you has a few comments on AstroEngine blog as well…

What gets me is the way that Pluto became a “planet” to begin with. It has always been a political planets. What else would one expect from the first “American found” planet. I take it you don’t like the current definition explanation saying that “a planet must reign supreme in its orbit”–or “It needs to have “cleared the neighborhood” of its orbit.”

In my opinion, It really should have never been a planet to start with.

2. Jorge Candeias - August 5, 2009

Hi. Thanks.

Yes, I do dislike the IAU definition, for a whole flock of reasons, which I’ll probly end up explaining if I really decide to revive the blog. Which I’ll probably end up doing.

Regarding Pluto, and paraphrasing some blogger from 3 years ago, who cares? 😉 Really, Pluto should never have been turned into the main issue of this discussion. It’s part of it, naturally, but it’s a tiny weeny part. The focus of it all should be much more in extrasolar planetary systems than in Pluto and the Kuiper Belt.

3. Tavi Greiner - August 5, 2009

“I would like to see people discussing the characteristics of the planets regardless of the characteristics of Pluto or its orbit.” Well-said!

I love, love, love this post. I, too, am puzzled by the debate over Pluto. IMHO, and at the risk of sounding like a curmudgeon, sentimentalism has no place in scientific formulation.

As we continue to discover more planets – particularly those many beyond our Solar System – it is important that we better define what exactly constitutes a “planet” and even expand upon the currently-limited classes to include a greater variety of planets; ie: is “gas giants” enough, or should there be sub-classes, etc. To suggest that we should not finetune our current definitions, even if it means moving a few things around, is to impede our greater understanding of the Universe.

Looking forward to following your blog!

4. Jorge Candeias - August 5, 2009

Tavi, thanks, and yes, I pretty much agree with everything you say.

5. Stop it already « Thousands of Planets - August 7, 2009

[…] them from other objects in the vast Universe without this kind of childishness? And can we please put Pluto aside while we do […]

6. Laurel Kornfeld - August 14, 2009

I am a writer who has been running a blog for three years advocating the overturning of the 2006 IAU planet definition, and from all this time of talking to people about the subject, I have an idea as to why many erroneously think it’s about Pluto. Pluto became the epicenter of the debate because when dynamicists claimed newly-found Eris isn’t a planet, that inevitably called into question the status of Pluto, which is somewhat smaller than Eris. Almost everyone is familiar with Pluto, but that is not the case with Eris or Ceres or Haumea or Makemake. If we had simply added the new objects and reinstated Ceres as a planet due to its being in hydrostatic equilibrium, public reaction would likely have been very positive. There is a sense of excitement in new discoveries, in finding out our solar system has more planets than previously thought. Instead, the focus became not the addition of these new planets and of what should have been a new planet subcategory, “dwarf planets,” but on the demotion of Pluto. In general, people respond positively to expansion and negatively to contraction. Entrenched in the public view as a planet and then demoted, Pluto became more than a celestial body. It became a symbol, enigmatic of academics perceived to be out of touch to the point that they created an absurd definition and expected the world to blindly follow it. Remember that the IAU decision did specifically focus on Pluto and did state that “the eight planets are Mercury through Neptune.” This set up Pluto as the Charlie Brown of the solar system, the consummate underdog. Whether we like it or not, everyone to some extent personifies inanimate objects. The Mars Rovers are affectionately referred to by those who run the program and by fans as “our girls.” With its eccentric orbit, extreme distance from the sun, small size and perceived random exclusion, how could Pluto not become everybody’s favorite underdog?

I agree with your planet definition and believe that once it becomes the scientifically accepted one (and I believe it will), there will be a new wave of interest in our new planets Ceres, Eris, Haumea, and Makemake, which are equally planets and equally fascinating.

7. Jorge Candeias - August 14, 2009

Well, that’s likely the case, yes. But I don’t think we should promote that kind of view. If there were good reasons to remove Pluto from the list of planets, it just should be removed without much hassle. I just happen to think there aren’t, otherwise I’d be squarely with Mike Brown and friends.

The focus should be put not on Pluto, but on the diversity of what really is out there, beyond Pluto, beyond the Solar System, even. Instead of riding the wave of largely ignorant indignation for a demotion that isn’t really a demotion, this should be used as an opportunity to explain to the public how our understanding of this matter was changed by the wondrous discoveries made in the last couple of decades.

I guess that makes me a “Pluto-hater” who happens to think Pluto is indeed a planet… 😉

8. Laurel Kornfeld - August 20, 2009

Sorry, but I don’t think you qualify as a “Pluto hater.” The main feature of Pluto haters is their insistence that Pluto not be classed as a planet but just as one more Kuiper Belt Object.

The kind of view that should be promoted is one that effectively says, “let 1,000 planets bloom,” focusing on the expansiveness of the term planet, how there are so many more planets of so many more types than were ever thought possible. People will naturally become excited about the “new” planets and seek to learn more about them–the same reaction now expressed with the discovery of ever more strange exoplanets. I’m all for focusing on the diversity out there. It’s those who insist on arbitrarily limiting the number of planets in our solar system to something “memorizable” who are impeding public education and enthusiasm about this diversity.

9. Jorge Candeias - August 20, 2009

Not a Pluto hater? Damn! I’m a misfit, then, since I’m not a Pluto hugger either… 😉

Seriously, though: I actually (and fully) agree with this comment of yours. That’s the reason why I called this blog “thousands of planets”.

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