Two weeks ago, while on my amazingly cool Astronomy course, my teacher decided the class to debate about wether or not Pluto should be a planet. before we started arguing though, she gave us the three definitions of a planet, according to the IAU:
1. It orbits the Sun 2. has enough mass and gravity to become almost spherical (hydrostatic equilibrium) 3. Has cleared the neighborhood around it
Now, if you look closely you may realize that number 3 is highly debatable (Number 2 in a sense as well): What is the definition of cleared up? You'd think it were 'the planet has absorbed, or thrown out of orbit all nearby objects. If that were true, then Jupiter wouldn't be a planet, because it has two asteroid groups orbiting with it.
I don't want to get into a lengthy tale about what happened in our classroom (It was mostly one group saying 'You're racists against little planets' and 'If we took out number three, we'd have 500,000 planets in the Solar System). Now I ask you:
Is Pluto a planet?
P.S: I don't want to hear a simple 'yes' or 'no', I want to hear why. This is a very debatable topic (So is everything else in Astronomy, but...), and I just want to hear what everyone thinks. I might debate a bit myself if this gets interesting.
According to the new definition, a full-fledged planet is an object that orbits the sun and is large enough to have become round due to the force of its own gravity. In addition, a planet has to dominate the neighborhood around its orbit.
Pluto has been demoted because it does not dominate its neighborhood. Charon, its large "moon", is only about half the size of Pluto, while all the true planets are far larger than their moons.
In addition, bodies that dominate their neighborhoods, "sweep up" asteroids, comets, and other debris, clearing a path along their orbits. By contrast, Pluto's orbit is somewhat untidy.
As another rule, the outer system consists entirely of gas planets. Is Pluto a gas planet? Or is it just a rock frozen due to very little warmth from the sun?
I'll post something more interesting later, once we get this debate underway again.
[quote="thelistman"]Who cares if it's a planet, a planetoid, or a goobley-boppy? It's there. It exists. No matter what we call it, it will not change a thing. It won't spin out of orbit or crash into the Earth if it's called something different.[/quote] It might. I think Pluto would maintain a great deal of internalised grief and will one day take it out on the Earth because we've recategorised it based on new information that for classifying bodies in space.
[quote="MoonFairy"]Who made the criterea for what to be a planet anyways?![/quote] International Astronomical Union, actually. It's a board made up of astronomers. They decide things.
As far as answering the question... yes, I do think Pluto should be considered a planet--but it's irrelevant. Despite the evolution of science and astronomy, Pluto's demotion is inconsequential--the 'debate' will continue and people will always think of it as a planet or accept it's a dwarf planet now or not give a flying fig either way.
The problem with our ninth planet, would be our tenth planet: Eris. Considered another dwarf planet, and larger than Pluto, the IAU still suffers the debate about both Pluto and Eris' classifications. Regardless, the term 'lanet' has sub-classifications--but it does not mean that Pluto and Eris are not planets--they are simply dwarf planets.
Verne Troyer is human, but specifically a dwarf human.
So, really, Pluto is, in fact, still a planet. The debate is only ongoing because ideas change, new information arises so definitions are altered, and that confuses/upsets/angers traditionalists. Classifying Pluto as a dwarf planet apparently makes the body less of a planet, which is not true. It is a planet, it just does not carry the same attributes as larger celestial bodies, so it therefore receives an alternate classification as 'ah, well, close'.
its not a planet, you need three things to make something a planet. 1. Cleared orbit of other objects 2. Orbits a star 3. Gravity has pulled it into a spherical this is what makes something a dwarf planet which is what Pluto is. 1. orbits the sun 2. Has NOT cleared orbit of other objects 3. gravity has pulled it into a almost spherical shape so there for, Pluto is not a planet its a dwarf planet.
they cant visit it. Its too cold. The outer planets are gas giants you cant step on them. Pluto is a giant rock of dirt and ice. Pluto could have gotten knocked out of the Oort cloud and then caught by the suns gravitational pull. All the dwarf planets have a gravitational pull. Pluto could have captured one of the asteroids from Pluto's orbit around the sun. And no all the asteroids wouldn't go with it because they would either have to be knock out of the Oort cloud or something.
[quote="MRWalker82"]Did you read the information in the OP?[/quote] Does it matter? This is supposed to be a personal opinion/debate thread. You also said, Given the accepted definition of what a planet is, it is obvious that Pluto does not fit all of the criteria. Correct, based on a new definition of what a planet is. That definition was redefined in, what, 2006? Therefore, there is a debate on whether or not that should be correct.
Also, I find it oddly satisfying to discuss Pluto's rights to be called a 'lanet'.
According to Wikipedia (which, I know, is not a real resource: Mike Brown, the astronomer who discovered Eris, said "through this whole crazy circus-like procedure, somehow the right answer was stumbled on. Itâs been a long time coming. Science is self-correcting eventually, even when strong emotions are involved."
The point that 'science is self-correcting' is interesting. Not all in the astronomical community accepted the reclassification and the new IAU definition of what a planet is. Science changes constantly. New discoveries are made. Astronomy is not as simple as it once was when Ptolemy first began pondering it--things changed, things were revisited. Remember the debate on a heliocentric universe? Pluto's reclassification is not much of a debate compared to that--Copernicus was, in the eyes of society, blaspheming according to the church, that it was false and against Scripture.
Similarly, the debate on Pluto's existence or non-existence as being a part of our solar system is frustrating for some. Even though it's still technically a planet--and it never left our solar system--renaming it is almost like dismissing it all together. The debate seems to be more on a ball of rock and ice's rights to a title. Perhaps we've come to that point in humanity where even a planet billions of kilometres away deserves something.
Does it matter? This is supposed to be a personal opinion/debate thread.
Point taken. Then let me put it this way. I am not an astronomer or cosmologist. I was not present at the IAU convention in which the topic was addressed. Because of that I tend to accept that a committee of the leading scientists in the field probably has a better grasp on the situation than I. I looked over the information, the debate for and against the new classification, and I admit that based on my limited experience in the field that the new definition seems both legitimate as well as necessary. Therefore I agree with the conclusion of the IAU.
