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Pluto May Soon Not Be A "Planet" ????

rockthecasbah

rockthecasbah

macrumors 68020
Original poster
Apr 12, 2005
2,395
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Moorestown, NJ
Astronomers are meeting to define what a "Planet" actually is. This decision could soon affect whether or not Pluto remains a scientifically-defined planet. Currently the argument is a stalemate, according to the article, about 50/50 for both sides. The main issue is Pluto's size. Once believed to be about Earth's, it has since been discovered to be smaller than our moon. Also setting apart is it's odd orbital plane, separating it from other planets.

Well call me old fashioned, but i consider Pluto a planet :p. The argument compares size, but what does that really matter if it exhibits planet-like aspects? I don't know, i guess that's why i'm not an astronomer right?

Link.
 
Whether Pluto is or is not a planet shouldn't really be a big part of the discussion. The real question is coming up with a definition of a planet. Once that's accomplished, Pluto will either meet that definition or not. Is Xena a planet? How do we determine going forward what constitutes a newly-discovered planet. How elliptical can its orbit be? How large does it have to be?
 
The problem with Pluto being a "planet" is that one of the new objects recently found (Sedna, I think it's called) is actually LARGER than Pluto. So if Pluto's a planet, shouldn't that larger, farther-out object ALSO be a planet?

I think it makes more sense to demote Pluto to a "trans-Neptunian object", even though for about 20 years of its orbit, it's inside Neptune's orbit.
 
Sedna is actually smaller than Pluto. "Xena" is the major one under discussion, as it's the largest of the Trans-Neptunian objects. There are a lot of them though, with more being discovered all the time. Where do we draw the line?

Edit: Here's a good summary of some of the options currently under consideration for defining what it means to be a "planet."
 
WildCowboy said:
Whether Pluto is or is not a planet shouldn't really be a big part of the discussion. The real question is coming up with a definition of a planet. Once that's accomplished, Pluto will either meet that definition or not. Is Xena a planet? How do we determine going forward what constitutes a newly-discovered planet. How elliptical can its orbit be? How large does it have to be?
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That's what the whole meeting is about, but the redefinition may exclude Pluto from being considered a planet which is the point of the article.
 
Any definition that defines Jupiter and Mercury as the same kind of thing is a little off to begin with. I imagine they might come up with a couple sub-definitions under the broader definition, leaving the "main" question of Pluto's status effectively unanswered.
 
Pluto doesn't meet the definition of a planet I think it should be grandfathered as a planet anyway.

Its like vowels a-e-i-o-u- and sometimes y. Pluto is the 'y'.
 
Pluto is not a planet.

it is a planet-oid.

it has an unsual elliptical orbit that is not even within the plane of our solar system, it travels at a tilt....

back in the day pluto made sense, but today it doesnt really, especially since, last I recall, part of its orbit brings it closer to the sun than Neptune....

im no astronomer but Pluto is prolly just a huge frozen rock left over from the formation of our solar system......orbiting forever like a comet does.

though the fact that it has "moons" makes it a planet in my book, no comet/asteroid, has orbiting smaller bodies.
 
Personally, I think this argument was started by the text book publishers. After Pluto is declared "not a planet," textbooks in every classroom around the world will have to be replaced. Cha-Ching
 
Dont Hurt Me said:
Problem is they just never defined a Planet very well, I like to think of Planets as Big enough Rocks to have or had a atmosphere.
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Last time I checked, Jupiter, Saturn, Neptune, and Uranus weren't really just "big rocks."
 
EricNau said:
Last time I checked Jupiter, Saturn, Neptune, and Uranus weren't really "big rocks."
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Neptune and Uranus aren't, they're mostly ice with enough gravitational pull to hold onto gas. Saturn is less dense than water (it would float if you could find a big enough pool) but still big enough to hold the gases in.

The core of Jupiter is believed to be metallic hydrogen but we can't really prove it until we can get a probe down there (ie never) so until then we have to infer.

A planet to me is something larger than some given size but not too large to become a star. Brown dwarfs aren't planets.
 
Abstract said:
It doesn't matter what we call it because it doesn't change anything, or help us solve anything.
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Indeed. This is not a very productive debate.

There doesn't seem to be any solid demarkation between any celestial body in space. There isn't really a size gap between big asteroids/planetoids and small planets. Heck, there doesn't even seem to be a gap between big gazeous planets ans small cool stars. Take a big enough gazeous planet, add a little mass, pressure/temperature increases, and Swoosh! nuclear fusion starts and you get a star. (don't try this at home kids)

This debate had been going on for years. It keeps popping back on slow news days.
 
The real question is, why the hell aren't scientists putting their time, resources, money and manpower together to find cures for things like cancer and aids instead of deciding if a giant lump of rock 2.6 billion miles from us is a planet or not :rolleyes:
 
yg17 said:
The real question is, why the hell aren't scientists putting their time, resources, money and manpower together to find cures for things like cancer and aids instead of deciding if a giant lump of rock 2.6 billion miles from us is a planet or not :rolleyes:
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We are...


Should we get rid of every activity that doesn't directly impact human health?
 
WildCowboy said:
We are...

Should we get rid of every activity that doesn't directly impact human health?
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^_^ Indeed. Astronomers/Astrophysicist wouldn't be able to contribute much to Cancer research.

But I'm pretty sure there are more important issues withing their field. One comes to mind: "How can we get Douglas Quaid's ass to mars withing the next 50 year?"
 
srobert said:
Astronomers/Astrophysicist wouldn't be able to contribute much to Cancer research.
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Actually, I'd be willing to bet they could. They're very smart folks...if they'd been trained as biologists, they'd likely be very good at it. Take a few years to retrain them and they'll be all set. But clearly that's not what they wanted to do with their lives, so more power to them. Issues like this are merely a sidelight to their real work of understanding how the universe works and what's out there. Which may become extremely important in the future.

There are an awful lot of people in the biology world who are working on things that aren't directly applicable to human health. But maybe at some point that work will be tied into some much bigger or open up a completely new and revolutionary avenue of research that will have such an impact.
 
I'd classify all Kuiper Belt objects larger than Pluto as planets and not worry about the textbooks. We have the Internet now, so we don't have to rely on out of date information. How many moons do Jupiter or Saturn have today?

If astronomers can declare any sun within 50 light years that wobbles a bit as having planets, I don't see what the problem is with having 30-odd planets that we do know are there in our own solar system.

Anyway let's start naming some of these rocks. That's where the real fun starts :)
 
WildCowboy said:
There are an awful lot of people in the biology world who are working on things that aren't directly applicable to human health. But maybe at some point that work will be tied into some much bigger or open up a completely new and revolutionary avenue of research that will have such an impact.
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Indeed. And who's to say that the cure for cancer won't be found in the eye mucus of a beach dweeling 12 meter long worm on the shores of a distant planet, discovered by and to which the course has been plotted by astonomers/astrophycsists. :D Ok, long shot I'll admit.

On another note. Many scientists agree that the survial of the human race is still very uncertain as long as we haven't settled other worlds orbiting other stars. As smart as we think we are, 1 big chunk of rock could send us all to space-pope heaven in an instant. Oooh the drama!
 
srobert said:
On another note. Many scientists agree that the survial of the human race is still very uncertain as long as we haven't settled other worlds orbiting other stars. As smart as we think we are, 1 big chunk of rock could send us all to space-pope heaven in an instant. Oooh the drama!
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I would think that without settling other planets or some other plan that doesn't rely on earth, the human race is guaranteed not to survive.
 
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