Comments on: Starlight http://it.gen.nz/2009/08/27/starlight/ Writings on technology and society from Wellington, New Zealand Wed, 02 May 2012 08:16:22 +0000 http://wordpress.org/?v=2.9.2 hourly 1 By: Lawrence D'Oliveiro http://it.gen.nz/2009/08/27/starlight/comment-page-1/#comment-6378 Lawrence D'Oliveiro Thu, 27 Aug 2009 10:06:13 +0000 http://it.gen.nz/?p=774#comment-6378 Pluto's orbit is highly inclined to the ecliptic (17°) and highly eccentric. Also it's very small—smaller than our Moon. So once Xena/Eris was discovered, and shown to be bigger, a decision had to be made: either that, too, was a “planet” (along with potentially dozens or hundreds of similar bodies that seem likely to be discovered in the future), or Pluto was not. So the term “planet” was reserved for really major bodies—well, at least as major as Mars and Earth. These smaller bodies—still large enough to be round rather than odd-shaped like most asteroids—are now to be called “dwarf planets”, or possibly “plutoids”, or something like that. Pluto’s orbit is highly inclined to the ecliptic (17°) and highly eccentric. Also it’s very small—smaller than our Moon. So once Xena/Eris was discovered, and shown to be bigger, a decision had to be made: either that, too, was a “planet” (along with potentially dozens or hundreds of similar bodies that seem likely to be discovered in the future), or Pluto was not.

So the term “planet” was reserved for really major bodies—well, at least as major as Mars and Earth. These smaller bodies—still large enough to be round rather than odd-shaped like most asteroids—are now to be called “dwarf planets”, or possibly “plutoids”, or something like that.

]]> By: colin http://it.gen.nz/2009/08/27/starlight/comment-page-1/#comment-6376 colin Thu, 27 Aug 2009 00:37:32 +0000 http://it.gen.nz/?p=774#comment-6376 Laurence Doesn't it? Bother, I was sure it did. Anyway it exhibits enough other pathological behaviour not to be a real planet. There's a great XKCD cartoon about it somewhere. Colin Laurence

Doesn’t it? Bother, I was sure it did. Anyway it exhibits enough other pathological behaviour not to be a real planet. There’s a great XKCD cartoon about it somewhere.

Colin

]]> By: Lawrence D'Oliveiro http://it.gen.nz/2009/08/27/starlight/comment-page-1/#comment-6375 Lawrence D'Oliveiro Wed, 26 Aug 2009 23:49:36 +0000 http://it.gen.nz/?p=774#comment-6375 Pluto does not go the wrong way round the Sun. Pluto does not go the wrong way round the Sun.

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