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.
As for Pluto being a planet i still usually regard it as one, just seems unnatural to believe in something your whole life no matter how minor and then suddenly disregard it. Also i read the article and i got to the part that said "This means that the Solar System consists of eight planets." I went back and read again and it didnt see where it explained why Pluto wasnt a planet. Unless it doesnt comply with the third rule, which i dont quite understand completely. It orbits the sun i know, is it round? I think. But the part about "has cleared the neighbourhood around its orbit." Does that that mean that something else doesnt share its orbit?
Well for me saying its a dwarf planet seems silly. According to your rules #3 wouldn't it not be a planet because of that orbit thing it does with neptune? Of course that means neptune isn't a planet either....Hmmm.
Well i dont think its a planet but i dont think its a dwarf planet only becuase pluto's "moon" is near the same size as pluto.also pluton is orbiting the moon and the moon is also orbiting pluton so they orbit each other which doesnt make sense so i would create a whole new catagory for it.
According to the new definitions of 'lanet' and 'dwarf-planet' then Pluto is obviously NOT a planet. As part of it's elliptical orbit it passes quite close to several other celestial bodies which exert great gravitational pressure on it and which overpower it's own gravitational forces. By this fact alone it is clear that Pluto has not, and is incapable, of completely clearing it's own space on the entirety of it's orbit and this is not a planet.
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.
Pluto is scientifically regarded as a large commet the last I checked, or whatever they call it these days. Personally it has some atmosphere so yes it is a planet.
Hu cares? I wouldn't make it a planet because that would mean that there are 4 rocky planets, then 4 gas planets, then, for some reason, another rocky planet.
I like saying "When I was in elementary, Pluto was a planet." I still think of it as a planet. I dont care about the mass. it has a neighborhood as you said. so in my book, it is.
At the moment, Pluto is considered a 'dwarf planet' because it follows criterion 1 and 2, but not 3. Eries and some other objects in the Kuiper belt are also considered dwarf planets.
Just because an object is in the Kuiper belt doesn't mean it has to be a comet (though granted, it probably is).
According to your rules #3 wouldn't it not be a planet because of that orbit thing it does with neptune? Of course that means neptune isn't a planet either....Hmmm.
Actually that has nothing to do with what I said, but I see where you're coming from. Neptune and pluto never really get that close, although it's believed in 200 million years or so Pluto will be so close to neptune it could possibly become a moon.
also pluton is orbiting the moon and the moon is also orbiting pluton so they orbit each other which doesnt make sense so i would create a whole new catagory for it.
Some planets wobble because of their moon's gravity. Another example is earth.
Personally it has some atmosphere so yes it is a planet.
Pluto's atmosphere is frozen most of the time. It's only when it is closest to the sun that it will melt for a short time.
Most people seem to think plump is not a planet. In class, I agreed with this statement, and I argued heavily for it.
I wonder if there is someone besides subzero who thinks it should be a planet...
You know, I had already graduated from university when it was decided that Pluto no longer fit the criteria for being a planet...
It was funny how when we walked into the Science classroom for the first day of school and on the list of planets, Pluto was crossed out and above it was written 'dwarf planet'.
This topic is dying... Not many are interested in Astronomy it seems. Even though some see it as the future of mankind.
