Posted on 05/26/2007 8:56:35 PM PDT by SunkenCiv
"IAU presented the resolution to its General Assembly on August 16, giving the roughly 2500 attendees more than a week to discuss it. But the committee expected clear sailing...Instead, the '12-planet proposal' went down in flames. Critics objected that planets should also be defined by their orbital dynamics, not just by their size and shape. All eight 'major' planets, they pointed out, were massive enough to sweep up, fling away, or gravitationally control all the debris in their parts of the early solar sys[t]em, but Ceres and Pluto [and other candidate 'planets' among Kuiper Belt Objects] were not... the absurdity of the current situation can be summed up very neatly by considering what will happen if and when, as is very possible, we discover an object in the Kuiper Belt or the more distant Oort Cloud -- or more than one object -- that is actually bigger than Mercury. By the IAU's current definition, these will be officially called "dwarf planets" while the smaller Mercury remains a regular "planet", thereby providing endless fodder for the likes of Jay Leno... I suspect that in the end the IAU will finally have to beat another embarrassing retreat and fall back on the common-sense dividing line: call everything above a certain average diameter (and/or a certain average mass) a "planet", and everything below that size a "nonplanet". Average diameter is a lot easier to determine for distant KBOs than mass is, and so would be better for the purpose -- unless we're talking about the planets of other stars, where we often know the mass before we know the diameter.
(Excerpt) Read more at spacedaily.com ...
Pluto has a larger sphere of influence than the Earth, simply because of its distance from the Sun. The hatchet job done on the planet Pluto came about due to the political need to bash the US (Clyde Tombaugh, who discovered Pluto, was an American) and for no other reason, IMHO.
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On this, screw the IAU. Pluto is still a planet in my book and the “dwarf planet” term seems clumsy.
Separated at birth?
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"To Pluto And Far Beyond" By David H. Levy, Parade, January 15, 2006 -- We don't have a dictionary definition yet that includes all the contingencies. In the wake of the new discovery, however, the International Astronomical Union has set up a group to develop a workable definition of planet. For our part, in consultation with several experienced planetary astronomers, Parade offers this definition: A planet is a body large enough that, when it formed, it condensed under its own gravity to be shaped like a sphere. It orbits a star directly and is not a moon of another planet. |
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