Right result, wrong reasons if you ask me. A planet is now "a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighbourhood around its orbit.".
So in the (admittedly unlikely) event that we discover, say, a twin Jupiter-Saturn size pair in orbit, they wouldn't count as planets. Nonsense. And if you apply criterion (c) rigorously, Neptune isn't a planet either since it hasn't cleared Pluto-Charon. Except a footnote to the resolution after "planet" says "The eight planets are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.", so it is a planet by fiat of the IAU even if you might reasonably argue it doesn't meet their criteria.
A complete mess, if you ask me.
I note, at least that the potential debate over whether celestial bodies which have not cleared their orbits should be dwarfs or dwarves has been avoided by dubbing them "dwarf planets".*
* The seven dwarf planets are: Doc, Grumpy, Happy, Sneezy, Bashful, Sleepy and Dopey.
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timeasmymeasure
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Date: 2006-08-24 02:15 pm (UTC)So in the (admittedly unlikely) event that we discover, say, a twin Jupiter-Saturn size pair in orbit, they wouldn't count as planets. Nonsense. And if you apply criterion (c) rigorously, Neptune isn't a planet either since it hasn't cleared Pluto-Charon. Except a footnote to the resolution after "planet" says "The eight planets are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.", so it is a planet by fiat of the IAU even if you might reasonably argue it doesn't meet their criteria.
A complete mess, if you ask me.
I note, at least that the potential debate over whether celestial bodies which have not cleared their orbits should be dwarfs or dwarves has been avoided by dubbing them "dwarf planets".*
* The seven dwarf planets are: Doc, Grumpy, Happy, Sneezy, Bashful, Sleepy and Dopey.