Reality Conditions

Thursday, August 24, 2006

Pluto no longer a planet

So says the definitive resolution of the International Astronomical Union. The provisional decision of last week, which kept Pluto's status as a planet and added three more planets to the Solar System by definitional fiat (see the discussions linked in this post) has been overturned by pressure of the "hard-liners". The main argument for the decision was, of course, that Pluto is known now to be just one more in a large class of trans-Neptunian objects, with no particular distinction among them justifying a special status for it. This is not clear, however, from the text of the press report:

Much-maligned Pluto doesn't make the grade under the new rules for a planet: "a celestial body that is in orbit around the sun, has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a ... nearly round shape, and has cleared the neighborhood around its orbit."

Pluto is automatically disqualified because its oblong orbit overlaps with Neptune's.

Instead, it will be reclassified in a new category of "dwarf planets," similar to what long have been termed "minor planets." The definition also lays out a third class of lesser objects that orbit the sun -- "small solar system bodies," a term that will apply to numerous asteroids, comets and other natural satellites.

The new definition makes little sense to me. What does "clear the neighborhood around its orbit" mean exactly? How does the overlap between Pluto's orbit and Neptune's disqualify "automatically" Pluto but not Neptune? I suspect there is some sloppy journalism going around here, and that the official resolution must be clearer.

Language Log's comment is:

The International Astronomical Union has spoken, and Pluto is no longer to be called a "planet." It is, however, still considered a "dwarf planet." Don't be fooled by any preconceptions you might have about English hyponymy: a dwarf planet is not, in fact, a planet.


  • Vamp, muy bueno ese language log


    By Anonymous Anonymous, at 4:48 AM, August 25, 2006  

  • De nada... quien sos?

    By Blogger Alejandro, at 3:11 PM, August 25, 2006  

  • soy largo, amigo de alejo

    el me mostró tu blog, está bueno! me hizo pertenecer a la blogosfera

    By Anonymous Anonymous, at 7:03 PM, August 25, 2006  

  • Pero entonces... ¿Plutón ya no es planeta? ¿Para la gente normal tampoco?

    By Anonymous Gin Connery, at 10:23 PM, August 27, 2006  

  • Ey! Los cientificos somos gente normal!

    En serio, dado que el habla cotidiana no se rige por los codigos de la IAU, todo depende si de la gente "normal" va a dejar de llamarlo planeta o no. Supongo que por el momento seguiran haciendolo pero que con el correr del tiempo los libros de texto de tu editorial y las laminas de la revista Billiken empezaran a usar la nueva definicion, y las proximas generaciones aprenderan desde chicos que en el Sistema Solar hay 8 "planetas" y muchos "planetas enanos", de los cuales Pluton es uno de los mas grandes.

    By Anonymous Alejandro, at 10:58 PM, August 27, 2006  

  • I am compiling a blogroll of atheists and agnostics. Do you consider yourself to be in either of these categories? And if so, would you like to be added to the blogroll?

    By Blogger beepbeepitsme, at 3:12 AM, August 28, 2006  

  • Not sure, beepbeep. I do consider myself an agnostic or an atheist (which of the two, it depends on the varying connotations given to the terms and also on my humor at the moment of being asked). However my blog does not cover the kind of issues you usually find in blogs dedicated to atheism and skepticism, and when I do discuss issues like "science vs religion" I try my best to do it in a constructive, philosophically detached way. So I would say that if you are making a list of "bloggers who happen to be atheist/agnostic" I am happy to be added (it would be a very long list I guess!) but if you are making a list of "blogs focused on atheism" then I pass.

    By Anonymous Alejandro, at 11:13 AM, August 28, 2006  

  • Welcome to the new blogroll :)

    Cerainly being part of the blog does not rely on your articles being predominately about agnosticism/atheism.

    By Blogger beepbeepitsme, at 6:35 AM, August 29, 2006  

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