I Wish I Knew How to Quit You, Pluto

By Julianne Dalcanton | March 13, 2010 12:10 pm

Oh dear. Sometimes it’s so hard to let go.

And most importantly, don’t forget to join us MARCH 13, at 1pm for the PLUTO IS A PLANET PROTEST MARCH AND RALLY. The march starts at the Greenwood Space Travel Supply store (8414 Greenwood Ave N) and will end at Neptune Coffee (8415 Greenwood Ave N).

But really, Greenwood Space Travel Supply is all kinds of awesome, even if they’re weirdly co-dependent with small rocks in the outer solar system. They’re the Seattle branch of the 826 network, which is a non-profit writing center for kids.

They also have cool t-shirts.

  • http://mengbomin.wordpress.com/ Meng Bomin

    The notion that Pluto is in the same category as the eight most massive non-stellar objects in our solar system will die with those who learned that it was in school.

  • NewEnglandBob

    Get over it. Get a life. Pluto itself doesn’t care. It just continues along, doing as it always has done..

  • Alex

    Hey Bob — you’re the one leaving comments on D list websites and you’re telling me to get a life?

    Now I’ve commented too, which means I DO need to get a life, but not for the Pluto thing.

  • Russell

    I don’t really understand this crusade, it seems very emotion based. If you want Pluto to be a planet so badly, then you really ought to be demanding that other Kuiper belt objects be classified as planets as well.

  • gopher65

    Russel: I don’t give a flying crap if Pluto is a planet or not. That’s not the point (for me at least. I realize some people have a weird attachment to Pluto).

    We now have a definition of the word “planet” that is dependant on the SIZE OF THE ORBIT of the object in question. IE, the larger an orbit is, the harder it is to “clear” the orbit of significant debris. If you put Earth out in the Oort Cloud, it wouldn’t be a planet under the new definition. That’s stupid. In fact, if we discover a Jupiter sized object in the outer reaches of the solar system (which is entirely possible), it won’t be considered a planet, even if it can be proven that it formed in the inner solar system and was tossed out there. Again, that’s stupid. Since this problem is obvious to your average third grader, either the IAU is filled with Forrest Gumpian class morons, or they just didn’t care that they’d created a dumb definition, as long as that definition excluded Pluto as a planet.

    I don’t care if Pluto is a planet or not. What I do care about is the faulty definition of a planet that the anti-Pluto zealots at the IAU pushed through for no other reason than because they didn’t like having an oversized comet as a planet.

    I’d agree that Pluto doesn’t fit in with the classical definition of planet. Ok. Cool. If you want to create a classical definition of “big things in the solar system that we arbitrarily call “planets”", then be my guest:P. I don’t care. It’s not a big deal. But that’s not what they did.

    If they didn’t want to mess around with the whole “arbitrary list of objects we call planets” idea, then they should have put some effort into creating a real definition, based on the physical properties of the objects in question. The easiest (and most correct) way to do this would be to create a spectrum definition, rather than a “line in the sand” type definition (they did the latter, of course). That would have solved the whole Gas Supergiant/Brown Dwarf issue too.

  • Charon

    “if we discover a Jupiter sized object in the outer reaches of the solar system (which is entirely possible)”

    Really? Well, it can’t have formed out there, so it must have migrated, which means there must have been some noncentral object way more massive to throw it out there (like the Oort Cloud is populated), and… oh wait, that doesn’t make any sense, because there is no such object to scatter it.

    “The easiest (and most correct) way to do this would be to create a spectrum definition”

    Um, no. Easy for stars – to first order they’re blackbodies, and to second order they have spectral lines that are just temperature dependent (metallicity contributes, though not as much – for the hotter stars, the atmospheric opacity is mostly hydrogen anyway).

    But planets? With spectral lines that just for terrestrial planets depend on, oh, the age of the planet, geological activity, the presence of life, proximity to their star… that sounds nuts.

    I might be totally wrong with all this. After all, I study the IGM, not planet formation. But… I kinda think the IAU definition, flawed though it may be, makes a hell of a lot more sense than anything you’re saying, gopher65.

  • http://telescoper.wordpress.com Peter Coles

    Based on the addresses of the start and end points, it hardly looks a strenuous march. How strongly do you have to feel to march all the way next door?

    For political reasons the IAU didn’t disclose its real definition of a planet, which is “any big thing in the Solar System which wasn’t discovered by an American”.

  • http://laurele.livejournal.com Laurel Kornfeld

    Nobody should “let go,” “get over it,” or blindly accept the controversial IAU definition, which does not even make scientific sense. The notion that Pluto is a planet–in the same broad category as the larger eight objects–will NOT die with those who learned it in school; in fact, many are still learning it in school today. Only four percent of the IAU voted on this, and most are not planetary scientists. Their decision was immediately opposed in a formal petition by hundreds of professional astronomers led by Dr. Alan Stern, Principal Investigator of NASA’s New Horizons mission to Pluto. Stern and like-minded scientists favor a broader planet definition that includes any non-self-luminous spheroidal body in orbit around a star. The spherical part is important because objects become spherical when they attain a state known as hydrostatic equilibrium, meaning they are large enough for their own gravity to pull them into a round shape. This is a characteristic of planets and not of shapeless asteroids and Kuiper Belt Objects. Pluto meets this criterion and is therefore a planet. Under this definition, our solar system has 13 planets: Mercury, Venus, Earth, Mars, Ceres, Jupiter, Saturn, Uranus, Neptune, Pluto, Haumea, Makemake, and Eris.

    Pluto is a planet; it is just one of a third subcategory of planets, the dwarf planets (in spite of the nonsensical IAU decree), in addition to the terrestrial and jovian planets.

    I wish I could have attended this demonstration, but I live on the other side of the country, and the trip is expensive. Maybe next year.

  • http://bulletproofcourier.blogspot.com bulletproofcourier

    I think the announcement was meant as a joke. They’re only “marching” across the street for coffee. (not next door: the address would be even)

  • http://mengbomin.wordpress.com/ Meng Bomin

    Pluto is a planet; it is just one of a third subcategory of planets, the dwarf planets (in spite of the nonsensical IAU decree), in addition to the terrestrial and jovian planets.

    By the same logic, I could formulate the sentence:

    153 Hilda is a planet, it is just one of a fourth subcategory of planets, the minor planets (in spite of the nonsensical IAU decree), in addition to the terrestrial, jovian, and dwarf planets.

    There is nothing inherently wrong with either statement. I agree with you that hydrostatic equilibrium is an important characteristic to consider. But nothing in the IAU’s decision suggests that they don’t consider it. They simply chose to appropriate the word “planet” to the big eight rather than to every round object directly orbiting the sun.

    Now, obviously you and Dr. Stern have a different opinion. But at this point we’re talking about aesthetics, not facts, and honestly I have a different aesthetic preference than you do. Personally I think that the terms “planets” and “dwarf planets” are less confusing term than Stern’s own “überplanets” and “unterplanets”, but then again, I’m not a Germanophile.

    In the end, we’re drawing a line in the sand that nature doesn’t heed in its actions. The point of these categories is for our own analysis. So there will be border cases that aren’t clear regardless of where we set the boundaries. You think that hydrostatic equilibrium should be the defining category, fine. You still have to deal with 4 Vesta, which doesn’t really qualify as what you termed as a “shapeless asteroid”, but isn’t truly in hydrostatic equlibrium either.

    Aesthetically, I like the fact that the term “planets” refers to the largest objects that dominate the solar system. Is it inconsequential that Pluto’s orbit is stable specifically because it avoids that of Neptune? Or that it’s less than 1/50 the mass of Earth’s moon? Or that these two characteristics are interrelated?

    Now, I say that the notion that Pluto is in the same category as the eight most massive non-stellar objects in our solar system because it’s true. As a child learning about the solar system, I was always struck by the incongruence of Pluto with respect to the other planets. Here we had a planet that was much smaller than Earth’s moon (as well as six other moons) and had an eccentric orbit crossing that of the much larger Neptune. It was an outlier.

    Now, we know that it wasn’t so much of an outlier as it seemed at the time. But that further emphasizes the point. There are a swarm of objects that are like Pluto. Don’t get me wrong, it’s toward the big end of the spectrum, but

    It’s much easier for a schoolchild to digest a view of the solar system dominated by eight planets than one where every round object that orbits the sun has spotlight significance. You claim that there are 13…there are 13 that have been recognized as such, but there are likely many more that will be recognized in the coming years. Pluto is an interesting body…but I don’t see it as being in the same league as the big eight (which one could break down further into terrestrial and jovian, or rock, gas, and ice according to one’s preferences). Having the big eight as planets makes for a much easier gateway to learning about the full array of interactions in the solar system than does starting out with the whole swarm.

    Ultimately, this strong-emotioned political movement over the naming of categories is silly and will be looked at as quaint by future generations.

  • Timothy

    Looking at the beginning of the post’s title, I was misled into believing you had another cool mnemonic for sqrt{2}

  • Badger3k

    Pluto is a planet. A dwarf planet, but that’s still got “planet” in it. So what if it’s also a Kuiper Belt object?

  • Russell

    It is very obvious that this is mostly an emotion based argument. This repetitious call that the IAU had made a “nonsensical decree” over the Pluto re-evaluation is is hilarious, because it is not without logic, Pluto does not conform. This argument that hydrostatic equilibrium is enough to be a planet is absolutely laughable, by this logic we should now classify stars and moons as planets as well. Astronomy is already a pretty hand wavy endeavor, lets at least demand that our planets are part of some semblance of harmony in the solar system, and not just every spherical object floating around the outer reaches of where ever.

  • Sili

    If people want Pluto to be a planet so badly, I suggest they start funding space research something fierce and go out there and clear it’s orbit.

    Squish together Pluto, Eris, Make-Make, that Q-thingie and the rest of the Kuiper Belt. Then you’ll have a planet.

    People keep saying that if we discover an ‘earth’ in the KB it won’t be a planet. Hvis og hvis min røv var spids …. Has anyone actually bothered to model it? Will an earth be able to exist out there without clearing its orbit?

  • andy

    Sili: regarding Earth in the KB, taking the überplanet/unterplanet distinction from equation 4 in Stern and Levinson (2000), I get a critical semimajor axis for Earth of about 2900 AU, so an Earth mass would probably have cleared the KB anyway. I note they use a Hubble time as the critical timescale, not the solar system lifetime – the equation seems to be linear in time, so putting in 4.5 Gyr instead of 12 Gyr results in a figure of roughly 1100 AU, still well beyond the Kuiper Belt.

  • gopher65

    I didn’t say “spectral” definition, I said “spectrum” definition. The latter is being used in the conventional sense of the word, not in the astronomical sense (although I can see how you’d have thought that). Spectrum definition as in “a definition that is spread across a range of values”; “continuum definition” would be a less confusing way to describe it.

    In other words you have a definition that starts with a single grain of dust (or maybe even a single free flying proton), goes up to a lump of dust, then a little rock, then a big rock, then a round rock, then an object with an atmosphere, then an object that is mostly atmosphere, then an object that can sustain tritium fusion, then an object that can sustain deuterium fusion, then an object that can sustain hydrogen fusion. There is no break between any of those points, because there are hybrid objects that would, in a classical definition scheme, fall into more than one category (or into none). The definition therefore is continuous, and flows from one object class into another.

    The definition can have new branches placed at any point along its length as new types of objects are discovered. It’s a versatile way to define a set of objects.

    In such a definition there is no clear (but arbitrarily placed) cutoff point between “rock” and “planet”, or between “planet” and “star”. The definition is based entirely on the physical properties of the object, rather than on a bunch of arbitrarily drawn lines in the sand.

  • http://thegreenbelt.blogspot.com The Ridger

    Mercury is tiny, too. It’s just inside the big ones instead of outside them.

    I’m not emotionally attached to Pluto, but this definition isn’t “better” than “big enough to be spherical and has its own moon”. And just why is “list short enough for schoolchildren to memorize” even advanced?

  • http://omnologos.wordpress.com Maurizio Morabito

    The main issue I have with the reclassification is that schools, textbooks, museums, movies, documentaries the world over have simply shortened the list of planets, so millions of kids have no idea there is anything like a “dwarf planet”, let alone that Pluto ever existed. They are shown a list of 8 objects and that’s it for the Solar System as far as they are concerned.

    For better or worse, the IAU has ended up furthering the cause of scientific ignorance. Think instead how rich their cosmos could be, were they to be told about Sedna, Eris, Makemake as a matter of course.

    Regarding #14 Sili “clear its orbit”: Pluto’s orbit is clear. There is no a chance in a billion years it will collide with anything, and it’s unlikely there is anything like a “Trojan asteroid” for Pluto either.

  • Aaron F.

    826!!! :D One summer in college, on the way to the supermarket, I did a double-take when I noticed that the store I was walking past was called “Liberty Street Robot Supply & Repair.” As it happened, I needed a small electric motor for a physics demo I was thinking about building, so I stopped in to see if they had any motors. The woman at the counter told me they didn’t actually sell robot supplies—just toys. I was so disappointed!

    Months later, I met someone who volunteered there, and she explained what they actually did… which is *almost* as cool as robots, I guess. ;)

  • http://omnologos.wordpress.com Maurizio Morabito

    Here’s an example of what I am talking about…the BBC using the term “humiliated” regarding Pluto’s “demotion”…


  • Mark

    I like the way the people who are with the IAU on this issue like to portray Pluto supporters as being emotional and irrational somehow. Very scientific; very civilized…very rational.

    *And just why is “list short enough for schoolchildren to memorize” even advanced?*

    Unless you have a real good memory, you’re probably going to have to look up Jupiter’s moons, there are so many. If we end up with 70 planets of the Sun because we have a sensible definition of a planet rather than the one that small group within the IAU manipulated the situation to establish in Prague, then so be it.

    *Ultimately, this strong-emotioned political movement over the naming of categories is silly and will be looked at as quaint by future generations.*

    You wish.

  • http://omnologos.wordpress.com Maurizio Morabito

    And here’s the New York Times talking about Pluto’s “demotion”

    “demotion”=lesser rank=lesser importance=incentive to schools, museums, etc to avoid talking about Pluto. And that’s exactly what they’ve been doing.

  • http://www.savory.de/blog.htm Eunoia

    BTW There is a ‘new’ Jimi Hendrix album just released. It is called ‘Valleys of Neptune’.
    Boy am I glad they went one planet further out ;-)

  • http://tispaquin.blogspot.com Doug Watts

    Mercury has no moon. Pluto does, and a big one, too. In any event, the controversy helps keep kids interested in astronomy and makes the IAU look like old crones from a Dickens’ novel. Once you demote Pluto, teachers will stop even mentioning its existence to kids because it’s not “even” a planet. What a great way to educate children.

  • uel

    I think something should be called a planet if it’s round due to it’s own gravitational field and orbits a star (and is not itself a star). If it’s round due to it’s own gravitational field but orbits something that orbits a star, then it’s a moon, and if it’s round due to it’s gravitational field and doesn’t orbit anything then it’s a planetoid.

  • ian

    Lets agree to disagree. There are 8 1/2 planets in the solar system.

  • Brian Too

    Someone mentioned that Earth’s Moon is easily big enough to be a planet. Plus I think that several others would be as well (Titan, Ganymede, Charon, just to start). We’d have to amend the definition to say “any gravitationally round body that clears it’s orbit and isn’t a star or a moon”.

    Just stirring the pot here!

  • nickandrew

    How ironic that a group of protestors rallying in support of the planetary status of Pluto
    should end their march … at Neptune.

  • locke

    Mike Brown expressed my favorite opinion on this: “Pluto is a planet because 6 billion people think it is” and then went on to explain that the word “planet” has always had a cultural, not a scientific, definition just as with the word “continent”. Then of course he ruined this perfectly good stand by wimping out because he apparently didn’t want folks to think he was just saying this because he wanted himself (and Trujillo and Rabinowitz) to be known as the discovers of the “tenth planet”. So sad, he was right the first time.

  • http://spacenow.com.br Alberto Geyer

    We managed to image Pluto in september 2008.The picture came across exceptionaly clear.It looked almost perfectly round.
    Then last march we took another shot of it and that was a
    shocker.There’s a giant mountain on the equator that casts a colossal triangular shadow to the right.
    We showed it to the IAU by their trianual general assembly in august.The president for planetary studies,Monsieur Regis Courtin,was intrigued but could’nt
    confirm the discovery for lack of another independent source for verification.
    The mountain in its various subsequent positions can be seen on http://www.spacenow.com.br/.
    Pluto might be a dwarf Planet now,but we know that it hosts the most striking surface feature in the solar system.


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