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IAU Demotes Pluto to 'Dwarf Planet' Status
Posted by
timothy
on Thu Aug 24, 2006 10:38 AM
from the and-then-there-were-eight dept.
from the and-then-there-were-eight dept.
davidwr writes "It's official. Pluto's been demoted. It's now one of several 'dwarf planets.' I guess we can drop the 'Period' from 'Mary's violet eyes make John stay up nights.'" (Of course, no one says you have to privately agree with the International Astronomical Union.) Several readers have contributed links to the BBC's coverage of the downgrade, as well as the usefully illustrated story at MSNBC.
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my take on it: (Score:5, Funny)
Re:my take on it: (Score:5, Informative)
I wouldn't call it a screw-up.
The draft proposal was:
Pluto would continue to be a planet, and Ceres, Charon and 2003 UB313 would become planets. However, this criterium is reached by hundreds, even thousands of other celestial bodies in our solar system. Under that proposal, all could gain planet status.
The final text is:
This definition does not define the terms "nearly round", nor "neighbourhood". But having a definition, rather than just an enumeration, is in my opinion a big leap forward. Demoting Pluto is a small price to pay.
I quite like the additional criterion of dominance of a body in its neighbourhood. It's not as arbitrary as simply requiring a minimum mass or size.
On the other hand, I do not like the fact that a planet should orbit to Sun to be called a planet. On this point, I preferred the original proposal in orbit around a star. I don't see why our solar system should be any different, why planet-like celestial bodies orbitting other stars are not called planets.
Parent
Re:my take on it: (Score:5, Interesting)
Pluto orbits the sun, but it also orbits a point in space above its surface. Charon doesn't orbit Pluto, but orbits a point in space above the surface of Pluto, while it too orbits the sun. Can someone explain to me why this shouldn't be called a double?
Parent
Re:my take on it: (Score:4, Interesting)
"is not a satellite" does not exclude Charon, because they picked a somewhat peculiar definition of "satelite" (barycenter of gravity inside the primary), which excludes almost everything we typically think of as a moon, but not Charon. This definition makes the Moon a satelite, but if the Earth had a slightly smaller radius but the same mass, the Moon would follow exactly the same orbital track, but suddenly be a planet.
I beleive they picked this definition of "satellite" specifically to exclude Earths Moon. If you actually plot the orbital tracks of the Moon, Charon, and any other moons you like, one stands out like a sore thumb as the one that should obviously be said to be orbiting the Sun. It's not Charon.
Parent
Re:my take on it: (Score:5, Funny)
What's he going to do now?
Parent
Re:my take on it: (Score:5, Funny)
At a rate of once every six days, nine hours, seventeen minutes, and thirty six seconds.
Parent
Re:my take on it: (Score:5, Funny)
Parent
Mnemonic device update (Score:5, Funny)
Now every geek's question is... (Score:5, Funny)
Re:Now every geek's question is... (Score:5, Funny)
Parent
Astrologers panic! (Score:5, Insightful)
So will this render all astrological predictions which took Pluto into account as invalid? I'm sure the kooks will come up with some excuse to explain how their previous charts were accurate at seeing the future as if they ~knew~ this all along.
Re:Astrologers panic! (Score:5, Insightful)
Parent
A new one (Score:5, Funny)
Why is this "breaking news" (Score:4, Insightful)
Now that would be breaking news!
Re:Why is this "breaking news" (Score:5, Funny)
Parent
That changes everything (Score:5, Funny)
Re:That changes everything (Score:5, Insightful)
Parent
So why does Neptune qualify? (Score:5, Interesting)
Re:So why does Neptune qualify? (Score:5, Informative)
Parent
Re:So why does Neptune qualify? (Score:5, Informative)
Parent
Holst was right. (Score:5, Funny)
Anyone? Anyone? (Score:4, Interesting)
Pluto is automatically disqualified because its oblong orbit overlaps with Neptune's.
1) - Is it possible for Pluto and Neptune to one day (like within the next couple billion years) collide? Or are their respective orbits degrading to the point where by the time they'd be near each other orbit-wise, their orbits would no longer overlap significantly? Or by 'overlap' do they mean "diagrammatically speaking, on a two-dimensional representation they overlap but even at their closest possible point they're still a squillion miles away from each other"?
2) - If so, how cool would that be? Would it be funny enough to make it onto an America's Funniest Home Videos video montage? Would it need special clown-horn-honking sound effects?
3) - Considering their distance from Earth and their relatively small size, would a collision of the two have any noticeable effect here on Earth?
4) - Seriously, how cool would worlds colliding be?! Costanza jokes aside, I think it'd be awesome to the max.
Re:Anyone? Anyone? (Score:4, Informative)
Is it possible for Pluto and Neptune to one day (like within the next couple billion years) collide?
Nope. Their orbits are in 3:2 orbital resonance [wikipedia.org]; basicly this means they constantly miss each other (a bit like your average commuter bus and train schedule :P). Also, due to the declination of the Pluto orbit it doesn't even touch the Neptune orbit. When seen straight from above, the orbits overlap, but if you go off-angle to just the right spot the Pluto orbit can be seen to be completely separated from Neptune.
Parent
Re:Stupid (Score:5, Insightful)
Given the level of scientific illiteracy, what the hell is the point of taking something that everyone does know and declaring it to be wrong?
"Everyone" knew there were eight planets prior to 1930. Did the world end when it was changed to nine, especially with something that wasn't even obviously a planet?
Guess what? A whole generation of children will grow up with the new, consistent rules and won't know any different. What's unarguable is that the new rules are better. I'm all in favor of fixing things that are broken, even if certain curmudgeons are too mentally inflexible to make the adjustment. See also: the metric system in the US, which is kept down by the same curmudgeons.
Parent
Re:Ok, so no we have... (Score:4, Funny)
Parent