Comments on Mike Brown's Planets: Free the dwarf planets!
I use this as an oppotunity to discuss Mike Browns...I use this as an oppotunity to discuss Mike Browns List of the possible dwarf planets.<br /><br />The first category should be divided in two sections: "dwarf planets according IAU" and "almost certain dwarf planets". It just makes not much sense to discuss any longer whether Pluto Ceres is a dwarf planet, because they are, according to the definition. (The definition is an other topic for discussion elswhere)<br /><br />As I understand the objects on the list are categorised according to diameter:<br />* > 900(800?) km<br />* 800-600<br />* 600-500<br />* 500-400<br />* 400-200<br />* < 200<br /><br />In my honest opinion the "probably not", everything smaler than 200 km in diameter, should be excluded. There is no trace of evidence for these objects to be even considered. (Until of course we find an object, that is less than 200 in diameter and perfectly round.)<br /><br />But there is a need for a category of objects, that were seriously discussed as possible dwarf planets (or even planets), but got rejected based on newer evidence like Vesta.<br /><br />The table uses diameter to decide which category, but the actual criteria is "roundness" There are objects out there that are over 500 km in diameter but not round enough to be a dwarf planet. So a rocky object or something with an iron core can be big and heavy but not round. Another object is just a flufy snowball, but as ice flows it gets round as we can see in some small moons of the gas planets. So diameter is only roughly connected to roundness.
I know you said not all TNOs need a name, but I th...I know you said not all TNOs need a name, but I think 2002 AW197 should be named Waton. Less than 2 weeks before its discovery Germany was the first country to adopt the Euro which was a major event in 2002, and Waton is kind like the Germanic creation deity since he and his brothers created the world from the body of the giant Ymir.
It's now been a full decade—a decade full of n...It's now been a full decade—a decade full of new dwarf planet discoveries and further confirmation of the dwarf-planet status of previously known bodies—and still we have only five "official" dwarf planets. In the meantime, an entire generation of school children has grown up learning that there are eight "real" planets, and memorizing the names of exactly five dwarf planets. A decade of books have been published including exactly five dwarf planets and completely ignoring the rest. And when a new dwarf planet candidate is discovered and announced, as UZ224 was just a few weeks ago, too many major news outlets still talk about dwarf planets in a way that makes it obvious the only one they've heard of is Pluto.<br /><br />The solution is for the scientific and lay community alike to simply start referring to all dwarf planets as dwarf planets. OR10, Quaoar, and Sedna are not "probable" dwarf planets—they *are* dwarf planets, just as assuredly as Eris, Makemake, and Haumea are. The same goes for Salacia, MS4, Orcus, Varuna, and a host of others that don't even have names. Creating the dwarf planet category and then abandoning has turned out to be even more irresponsible than just saying everything's a planet would have been, because it separates out the "special five" and then ignores the fact that a major reason for the creation of the category was precisely that there were so many of them!<br /><br />Even by the most conservative estimates, we have already discovered at least 50 dwarf planets. (See my own list at https://goo.gl/9Z2rJe.) That's ten times more than the five many consider to be the only dwarf planets! And when I think about reasons people haven't embraced the larger dwarf planet community, the answer is simple: It's much easier to have a tidy list of exactly eight main planets and five dwarf planets. With such a small list, kids can not only memorize the eight planets, they can memorize the dwarf planets, too! And in a few more years, when the IAU finally comes around to designating another batch of "official" dwarf planets, students, parents, and teachers will probably argue that they can't, because it would just be too hard to memorize them all. Wouldn't that be ironic?
I think 2002 ms4 should be named Ababinili after t...I think 2002 ms4 should be named Ababinili after the Chickasaw creation deity. The Chickasaw were native to Huntsville, Alabama; Mike Brown's home city.
Great post and list! But I noticed Charon isn'...Great post and list! But I noticed Charon isn't on it. Was that an oversight, or is there a particular reason you excluded it?
I teach cosmology at Fox Observatory and that'...I teach cosmology at Fox Observatory and that's one of the favorite questions, specially from parents. I love to show your list and see the faces :O . I just have one pet peeve about "dwarf" planets; the anglicanism dwarf doesn't translate well in many languages, it sounds offensive sometimes. I know it is way above my pay grade as an amateur astronomer, but I'd love to keep it in Greek notation: planet and planetoid.
I believe that the dwarf planet definition is fine...I believe that the dwarf planet definition is fine as-is, it shouldn't be a subcategory of planet. If people REALLY insist, I'd be ok with "major planet" and "dwarf planet" both being considered types of planets, but I'd prefer the current system. Anyway, the IAU needs to get off their asses and declare which known bodies are dwarf planets already. I mean how is Sedna, with all its fame, not listed yet? There are 23 known ones with a median diameter estimate of 600 km or more.
Having moons is not a good reason to be considered...Having moons is not a good reason to be considered as a planet : we know many small asteroids or alike objects that have satellites while two of the Solar System planets (Mercury and Venus) don't !
I suggest that Charon also be added to ...Dear Mike,<br />I suggest that Charon also be added to the list, since the Pluto-Charon system is more like a double-dwarf-planet system than one main orbited by another smaller one. The case of the Earth-Moon system as double-planet system, and hence of the Moon as a (dwarf) planet, could also be discussed. The other smaller "cisneptunian" objects that fit your definitions should also be added to the list, currently limited without any really good reason to the transneptunions objects.<br />Cheers,<br />Adrien
Dear Mike, I've seen the last update of your l...Dear Mike, I've seen the last update of your list of candidates. I remark that Ceres, one of the 5 IAU-recognized dwarfs, is missing in the list -- as well as Vesta, objet for which it is still unclear if it is in hydrostatic equilibrium and that could be at some point considered as a dwarf planet. Thank you in advance for completing the list with those few objects of the main belt and not limiting it to the TNOs.<br />Best regards,<br />Adrien Coffinet - PhD student at the Observatory of Geneva.
I don't like the idea which is promoted that P...I don't like the idea which is promoted that Pluto is not a planet. It IS a planet. In fact what the IAU decision amounts to, is saying that Pluto is too small to be a "major planet", but it did not really decide that it wasn't a planet. Why else would they call it a "dwarf planet" if it were not indeed a PLANET. I think every large round body that orbits around the Sun, and especially those that have moons (as Pluto does), are definitely planets.
Dear Mr. Michael Brown,
i just wanted to let you ...Dear Mr. Michael Brown, <br />i just wanted to let you know that i honestly think that you didnt kill pluto by discovering Eris, Quaoar, Sedna etc. i just finished a book called "the pluto files" by Neil Degrasse Tyson (whom i personally think IS the REAL pluto killer) and the one who started this pluto scandal (which i like to call "Plutogate") <br /><br />I think Mr. Tyson is the real pluto killer because he "had no compulsion to include pluto"(the pluto files page 78) when he reopened the rose center in 2000. is he prejudiced against pluto? The Rose Center nor Mr. Tyson will see me there. not worth my time.<br /><br /> i read an article in "Astronomy" magazine about Pluto and S. Alan Stern said that the IAU "embarrassed itself" and also used the words "stupid" and idiotic" to describe the IAU. then Mr. Stern, according to Astronomy "played a mean game of what if: what if you moved pluto into Venus' orbit? what if you moved jupiter into Pluto's orbit?"<br /><br />Earth has stuff going around it, is it a planet? <br /><br />to me Mr Brown, you are NOT the pluto killer. You introduced me and other astronomy fans to new planets to love and adore. thank you :)<br /><br />have a great day :)<br /><br />Sarah Aka Princess Pluto :)
Sarah Aka "Princess Pluto"firstname.lastname@example.org:blogger.com,1999:blog-9094742788006644220.post-25625932899405777482012-04-27T19_41_11.625-07_002012-04-27T19_41_11.625-07_00
Some pretty amazing data recently (april 2012) on ...Some pretty amazing data recently (april 2012) on the binary Salacia/Actaea system. Now that the mass (4.5E20 kg) and diameter (900 km) of the primary appear pretty accurately determined it turns out that its density is only around 1.2. This is so low that it might be the case that Salacia has voids inside. If it has then it is not in hydrostatic equilibrium. And if that is the case, then the assumption that a diameter of 800 km guarantees 'roundness' no longer holds. Am I right in thinking that the estimated number of dwarf planets could come down from around 400 to maybe no more than 50 or so?<br /><br />Eric, Netherlands
In the spirit of "Free the Dwarf Planets,&quo...In the spirit of "Free the Dwarf Planets," I wanted to share this YouTube video of the song "Pluto's Not A Planet Anymore":<br /><br />http://www.youtube.com/watch?v=xqGOghSgnYs <br /><br />--Dan Furman
I read this because the new images of Vesta by Daw...I read this because the new images of Vesta by Dawn and re-reading the Stern/Levison(2000) and Soter(2006) papers reminded me of the 5th anniversary, not of Pluto's demotion, but of the incredible and long overdue PROmotion this first known trans-neptunian and its discoverer received back then. I always felt the whole 'UB313 story in all its detail and strife finally put Tombaugh firmly on the high pedestal he had earned himself long ago doing the mental equivalent of hard labor that none of the v.i.professional astronomers seemed to have time for at the time, regarding how long all those plates were waiting in the archives before they were blink-compared by him. Whether it was their lack of endurance or their energy spent fighting off the latter-minute claims to the observatory from Lowell's heirs - they all missed the Pluto precoveries going back to 1909 or so. Not the IAU or anybody else, but the fact that he did not, and worked hard for it like the proverbial farmboy from Kansas flogged out of college by hailstorm, has put Tombaugh among the great first discoverers of the Solar System: Herschel, Piazzi, LeVerrier, Adams, Tombaugh - visual, mathematical, photographic. (Sorry, no-one yet to add 'CCD' to the list at this level. :-/ But I think 'nearly certainly' at the level shared with purposeful patience and dilligence and Karl Ludwig Hencke... ;-) And then, it took more than 60 and 70 years, respectively, to discover just one more object in the same region as Pluto, and then one of similar size out there. For the main belt asteroids, it took only 3 to 7 years for the first few to follow in the same sense. What's more, some of those great first discoveries were actually quite borderline cases in one way or another; e.g. Uranus and Vesta being naked-eye objects at least occasionally, Pallas and Juno bright and close enough to be stumbled upon in the chase after Ceres, or Neptune being only close to the center of the huge error bars by a good measure of luck and best estimate. Pluto clearly was not. It could not have been found much earlier (maybe ten, fifteen years or so at most for the first precovery plates of the same observatory archive series or quality) or with less effort (unless cracking the jackpot on the first try). No other was found by Tombaugh himself trying for many years until he was satisfied that none could be expected to be found with the means at his disposal. Intentionally or not, this was what the IAU finally confirmed five years ago, removing Tombaugh (and 'nearly certainly' others) from the list of la(te)st discoverer(s) of eccentric footnote oddball planet-a-likes - the gatekeeping of which the discovery intervals of Uranus, Neptune, Pluto, Eris might have suggested five years ago. And yes, I still chuckle thinking of Xena and Gabrielle in this context, and hope that the IAU might dare to decide to orbit Eris (everlasting trouble) at a semi-major axis large enough to let a little Dysnomia (lawlessness) reign over its lists and allow observation and common sense determine what to make of all those rounded rocks out there. ... ... Now, where do I put Vesta?? ;-)<br /><br />all the best and dark skies,<br />Jan Thimo Grundmann, Bremen, Germany
Just noticed that your list doesn't include ma...Just noticed that your list doesn't include mass. For binaries, an accurate mass is likely to be found sooner than an accurate diameter (like Pluto, Eris, Haumea, Quaoar, and Orcus ). Dwarf likelihood could also be inferred from the mass in these cases. E.g., what's the theoretical possiblility of something > Yg not being round?
To whom it may concern:
I am not sure what all th...To whom it may concern:<br /><br />I am not sure what all the hullabaloo is all about, regarding Pluto. Pluto is still a planet, it is just another type of planet, i.e. a dwarf PLANET.<br /><br />Other types of planets include proto planets, terrestrial planets, gas planets, exo planets or extra Solar planets, etc.<br /><br />Pluto has not changed, it is still where it has been for a very long time. Pluto is intact and is among many other worlds in that part of the Solar system. <br /><br />Pluto is not dead any more so than Jupiter, Venus, Sedna or Earth, is. <br /><br />So why are so many people so upset over an adjustment in how astronomers categorize it? <br /><br />Pluto, whether a KBO, TNO, planet or dwarf planet, is still just Pluto.
Obviously categorizing an object as "star&quo...Obviously categorizing an object as "star", "planet", "dwarf planet" or anything else is only relevant for the big picture. It helps to be able to talk in shortcuts. For individual cases only the actual values and measurements matter. No physical value on Pluto changed one bit in 2006, obviously.<br /><br />Still, I think it would help if the IAU released what they now apparently feel as their responsibility for dwarf planets. Dwarfs are currently only 'recognized' if the IAU is 100% sure about their 'roundness'. But how can they be sure if even that is not an exact physical parameter (Vesta is a good example where roundness is disputable)? The current list of 5 dwarfs is very misleading.<br /><br />So the IAU should give up entirely administering the dwarfs and leave it up to the researchers. We will get many databases with many different entries. But so what? As you said very correctly, that's science. Over time many entries will converge.<br /><br />And we might want to leave it up to someone at Wikipedia to summarize all those databases :-) .<br /><br />Eric, Netherlands.
To all of whom it may concern:
We seem to be caug...To all of whom it may concern:<br /><br />We seem to be caught up in a tangled web of definitions, classifications, categories, jargon etc., all in the name of science; I think not. <br /><br />Science is to help codify understanding of our universe. Science should be usable by all, not just scientists. We use objective criteria only, when employing scientific principles. Politics, egos, ambition, culture, religion, pride, reputation and the like should be kept in a lock box when using science.<br /><br />I sure hope that the IAU abandons its ill-conceived notions, confusing rules, and requirements etc., in favor of a neat, clean and polished approached to astronomy and science in general.<br /><br />It sure is difficult for lay people such as me, to understand all of the perplexing elements that the IAU adopted and seems fit only for an elitist scientific body. It is also egotistical for the IAU to think that all of this is for their benefit, only.<br /><br />It seems clear, that in a decade or two, the IAU (with a better understanding of the newly discovered bodies in our Solar System and will have to go back and clean up the mess they made.<br /><br />Now that exo-planets are beginning to be discovered, are we going to argue over another, perhaps more puzzling way, to classify them?<br /><br />I am sure glad that the IAU did not write our Constitution; if they did, our wonderful country would be swallowed up by a very unscientific black hole.
And by what eight names should all the people in t...And by what eight names should all the people in the world be called so that we don't cause our school children's brains to explode?
I've noticed that "world" has become...I've noticed that "world" has become a very handy catch-all term for planets, dwarf planets and large, roundish moons. It has the advantage of not carrying all of the baggage of the word "planet".<br /><br />Bob Shepard of Denver
@Mike Oh, yeah, the post! Very cool, by the way, a...@Mike Oh, yeah, the post! Very cool, by the way, and I fully agree - even if I lost sight of what we were talking about. :)<br /><br />@Anonymous Kids can still memorize the 8 "major" planets at a young age and have interesting discussions as they get older about "other kinds of planets." I know not everyone will have my unhealthy obsession with dwarf planets (business man by day, dreamer of distant worlds by night), but I want everyone to know they're out there. One of the greatest moments of my life was when I realized that the moon wasn't just some crescent-shaped atmospheric phenomenon, but a whole actual PLANET close enough that we could fly to it. I want my kids - and everyone's kids - to have a similar opportunity to behold the wonders our immediate cosmic neighborhood has to offer.
If we use science, Pluto is a planet. If we use po...If we use science, Pluto is a planet. If we use politics and talk about killing planets, then Pluto is Mickey's dog. If Earth was in Pluto's orbit, it would not be a planet. In fact, since Earth shares its orbit with at least two asteroids, the IAU could deplanetize Earth as well, using the ridiculous 2006 definition of a planet. Soon the IAU will change this absurd definition when New Horizons reaches Pluto and makes scientists realize the awesome planetness of Pluto.<br /><br />(fixed a few typos.....)
If we use science, Pluto is a planet. If we use p...If we use science, Pluto is a planet. If we use politics and talk about killing planets, then Pluto is Mickey's dog. If Earth was in Pluto's orbit, it would not be a planet. In fact, since Earth shares its orbit with at least two asteroids, the IAU could deplanetized Earth as well, using the ridiculous 2006 definition of a planet. Soon the IAU will change this absurb defintion when New Horizons reaches Pluto and makes scientists realize the awesome planetness of Pluto.