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| Science & Technology |
| Pluto Is Still A Planet |
| 2006-08-16 |
| Meanwhile - Nerds in Paradise. Astronomers meet in Prague... IAU Planet Definition Committee The IAU has been the arbiter of planetary and satellite nomenclature since its inception in 1919. The various IAU Working Groups normally handle this process, and their decisions primarily affect the professional astronomers. But from time to time the IAU takes decisions and makes recommendations on issues concerning astronomical matters affecting other sciences or the public. Such decisions and recommendations are not enforceable by any national or international law; rather they establish conventions that are meant to help our understanding of astronomical objects and processes. Hence, IAU recommendations should rest on well-established scientific facts and have a broad consensus in the community concerned. Ron Ekers, President of the IAU "The boundary between (major) planet and minor planet has never been defined and the recent discovery of other “Trans-Neptunian Objects” (TNOs), including some larger than Pluto, triggered the IAU to form a working group on “Definition of a Planet” from its Division III members. While there was general agreement on all the scientific issues related to Solar System dynamics and physical properties of planets, the IAU Division III Working Group could not agree on aspects that were related to social and cultural issues, such as the status of Pluto. In order to include these broader aspects, the IAU Executive Committee (EC) formed a new committee whose membership had backgrounds in history, science publishing, writing and education as well as in planetary science. Terms of Reference The Planet Definition Committee of the IAU Executive Committee was charged with: (i) discussing the broader social implications of any new definition of a planet and recommending a course of action that balances the scientific facts with the need for social acceptance of any change; (ii) addressing the status of Pluto, and of the newly discovered TNOs in the light of recommendation (i); (iii) considering whether the current naming procedures for planets and minor planets have exacerbated the problem of defining a planet and recommending whether revisions are needed; and (iv) attempting to frame these recommendations as a resolution, or resolutions, that could be put before the Prague GA in August 2006 for possible adoption. And you all thought the US congress got wordy.... My my my... --------------------------------------------------------------- Resolution 5 for GA-XXVI: Definition of a Planet Contemporary observations are changing our understanding of the Solar System, and it is important that our nomenclature for objects reflect our current understanding. This applies, in particular, to the designation “planets”. The word “planet” originally described “wanderers” that were known only as moving lights in the sky. Recent discoveries force us to create a new definition, which we can make using currently available scientific information. (Here we are not concerned with the upper boundary between “planet” and “star”.) The IAU therefore resolves that planets and other Solar System bodies be defined in the following way: (1) A planet is a celestial body that (a) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape1, and (b) is in orbit around a star, and is neither a star nor a satellite of a planet.2 (2) We distinguish between the eight classical planets discovered before 1900, which move in nearly circular orbits close to the ecliptic plane, and other planetary objects in orbit around the Sun. All of these other objects are smaller than Mercury. We recognize that Ceres is a planet by the above scientific definition. For historical reasons, one may choose to distinguish Ceres from the classical planets by referring to it as a “dwarf planet.”3 (3) We recognize Pluto to be a planet by the above scientific definition, as are one or more recently discovered large Trans-Neptunian Objects. In contrast to the classical planets, these objects typically have highly inclined orbits with large eccentricities and orbital periods in excess of 200 years. We designate this category of planetary objects, of which Pluto is the prototype, as a new class that we call “plutons”. (4) All non-planet objects orbiting the Sun shall be referred to collectively as “Small Solar System Bodies”.4 1 This generally applies to objects with mass above 5×1020 kg and diameter greater than 800 km. An IAU process will be established to evaluate planet candidates near this boundary. 2 For two or more objects comprising a multiple object system, the primary object is designated a planet if it independently satisfies the conditions above. A secondary object satisfying these conditions is also designated a planet if the system barycentre resides outside the primary. Secondary objects not satisfying these criteria are “satellites”. Under this definition, Pluto’s companion Charon is a planet, making Pluto-Charon a double planet. 3 If Pallas, Vesta, and/or Hygeia are found to be in hydrostatic equilibrium, they are also planets, and may be referred to as “dwarf planets”. 4 This class currently includes most of the Solar System asteroids, near-Earth objects (NEOs), Mars-, Jupiter- and Neptune-Trojan asteroids, most Centaurs, most Trans-Neptunian Objects (TNOs), and comets. In the new nomenclature the concept “minor planet” is not used. --------------------------------------------------------------- Remember if it is settled, the ACLU will unsettle it. Pluto had no worries. It will always be a planet. |
| Posted by:BigEd |
| #12 It may be time to build a wall, to prevent illegal immigrant Plutonians from taking all the jobs Mexicans do not want. |
| Posted by: john 2006-08-16 21:07 |
| #11 "Pluto is just another Mickey Mouse planet". Mork from Ork |
| Posted by: Deacon Blues 2006-08-16 20:59 |
| #10 Ed: in my day job, I translate Legalese to English and back again. |
| Posted by: Mike 2006-08-16 15:29 |
| #9 Pluto: a fine new homeland for certain inhabitants of Judea and Samaria...and all of Gaza. |
| Posted by: borgboy 2006-08-16 15:28 |
#8 I'll have trouble memorizing the mnemonic
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| Posted by: Eric Jablow 2006-08-16 15:22 |
| #7 if we try to tell six billion people that something isn't a 'planet' that they're used to calling a 'planet,' they won't go along with it and we might look silly. Therefore, we will construct our definition so that doesn't happen LOL Mike.... Someone ought hire you as an interpreter for the Bureaucratesian tongue. |
| Posted by: BigEd 2006-08-16 15:20 |
| #6 I think the phrase "broader social implications" was a polite way of saying "if we try to tell six billion people that something isn't a 'planet' that they're used to calling a 'planet,' they won't go along with it and we might look silly. Therefore, we will construct our definition so that doesn't happen." |
| Posted by: Mike 2006-08-16 15:10 |
| #5 Extraordinarily discouraging that the first item on reviewing a scientific definition is the "broader social implications" of a change. This group belongs in the same dustbin as religious and soviet scientific groups. |
| Posted by: DoDo 2006-08-16 14:57 |
| #4 Yeah, biyatch. Ima planet now, too. Lemme tell you how we livin now. |
| Posted by: Charon 2006-08-16 14:53 |
| #3 Actually, it was a pipeline that ran under the English Channel to deliver petroleoum products to support the D-Day invasion. Petroleum and Libricants Under The Ocean |
| Posted by: kelly 2006-08-16 14:50 |
| #2 I'm very confused, I thought Pluto was a dog. |
| Posted by: anonymous5089 2006-08-16 14:42 |
| #1 Well, once it becomes the 38464th holiest site in Islam, its future will be secure. Imagine the seeting if it were downgraded. Eye-rolling, perhaps. |
| Posted by: Jackal 2006-08-16 14:12 |