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2006-09-10
I commented already on the IAU's provisional definition of 'planet' but I have not said anything about their final decision yet. Anyone curious can read it here. One thing that has been pointed out is under this definition strictly speaking there are not planets in the entire universe but those of the solar system. So obviously either that is a mistake or this definition is still temporary, I guess to answer the urgent question (that's only semi-ironic, dear reader) of whether Pluto is or is not a planet.
Where the provisional definition required a planet to be roundish and orbiting the (a) sun the new definition says it has to have cleared the area about its orbit too, and if it meets the criteria otherwise it is now not a planet but a dwarf planet. And Pluto, being merely one among many objects inhabiting the Kuiper Belt, is a dwarf planet. Like the last one I think this definition is close but not quite there. At least it uses something of the major/minor planet distinction I wanted although I would have preferred it to have explicitly used those categories under the umbrella term planet.
My other disagreement is the IAU's continuing intention to use Pluto as the prototype of a new category. It is already the protoype of a class of objects: Plutinos. Originally I did think Pluto should be demoted outright but since coming on my current definition a few years ago, I'm going to stick with that until someone convinces me there's a better one. So Pluto is a planet still, but a minor one. So is Ceres, and Charon, and probably a few thousand other bodies not one light year from where I sit.
Okay, better stop now, getting ranty.
Peace, Tricia
Where the provisional definition required a planet to be roundish and orbiting the (a) sun the new definition says it has to have cleared the area about its orbit too, and if it meets the criteria otherwise it is now not a planet but a dwarf planet. And Pluto, being merely one among many objects inhabiting the Kuiper Belt, is a dwarf planet. Like the last one I think this definition is close but not quite there. At least it uses something of the major/minor planet distinction I wanted although I would have preferred it to have explicitly used those categories under the umbrella term planet.
My other disagreement is the IAU's continuing intention to use Pluto as the prototype of a new category. It is already the protoype of a class of objects: Plutinos. Originally I did think Pluto should be demoted outright but since coming on my current definition a few years ago, I'm going to stick with that until someone convinces me there's a better one. So Pluto is a planet still, but a minor one. So is Ceres, and Charon, and probably a few thousand other bodies not one light year from where I sit.
Okay, better stop now, getting ranty.
Peace, Tricia
