New Definition of "Planet" Might Not Include Pluto

I think for historical reasons, considering when it was discovered, Pluto should be refered to as a planet.

Originally posted by Toromos
Don't most planetary scientists consider the prospect of defining what a "planet" is somewhat arbitrary?

Yes, and partially that is due to the confusion as to whether or not Pluto should be called a planet. I'm sure that once a set definition is agreed upon, that abitrary definition will become quite scientific.

Originally posted by nogirt
I think for historical reasons, considering when it was discovered, Pluto should be refered to as a planet.

People thought the world was flat for the longest time. Since that was before what we currently know and have established scientifically, should we call it flat anyway, just for historical reasons?

People thought that galaxes were other solar systems for the longest time. Since that was before what we currently know and have established scientifically, should we call them solar systems anyway, just for historical reasons?

People thought that undiscovered, unmapped, or just unexplored areas of the Earth contained demons, monsters, or worse. Since that was before what we currently know and have established scientifically, should we say they contain demons, monsters, or worse anyway, just for historical reasons?

Do you get my point?

[edit on 8/15/2006 by cmdrkeenkid]

Pluto should remain a planet because it would be too expensive to replace all the forty year old science books our public schools use.

Sheesh... only eight planets... no such thing as electron orbits... think of the chaos that would ensue!?!

Originally posted by Toromos
Don't most planetary scientists consider the prospect of defining what a "planet" is somewhat arbitrary? It is a kind to geographer's trying to define what a continent is. For example, why is Europe a continent? It's not a separate land mass. Indeed, it's separation is political in nature. Why not consider Greenland, or Madagascar continents? Is it size? Why impose a size limit?

I guess my point is, for most scientists studying these objects, the appellation of "planet" or some other label is rather meaningless.

There's a good interview with Mike Brown, the discoverer of Sedna, Xena, and the other KBO at:

www.discover.com...

where he discusses the arbitrariness of defining what a planet is.

It deals with cuture and not trying to upset a mass number of people. Truely Europe should be considered a subcontinent of Eurasia.

For example, why is Europe a continent?

It shouldn't be. It's one of the dumbest definitions in all of human history. A bit like calling Charon a planet.


[edit on 17-8-2006 by Mogget]

[edit on 17-8-2006 by Mogget]

Originally posted by Mogget

For example, why is Europe a continent?

It shouldn't be. It's one of the dumbest definitions in all of human history. A bit like calling Charon a planet.

Actually Charon should be considered a planet since both Pluto and Charon consist in a biplanetary system as they both orbit about each other. A moon is simply a celestial object that orbits about another object that isn't a sun.



But here is something I think people aren't taking seriously.

Anyone that thinks the criterion, "a planet must be 'by far the largest body in its population of bodies" should be added into the definition of a planet is beyond the help of re-education.

Where would someone come up with such a stupid and brainless idea?

Population of bodies? Associating that with Pluto does that refer to... all Kuiper Belt objects?

Well let me show you something that makes that idea the stupidest ever made.



That chart shows the entire distribution of asteroids in the solar system. The main belt is highlighted in red and it shows us the primary distribution of asteroids and the main belt in the asteroid belt. The actual asteroid belt consists of all those little blue and red dots you see scattered throughout that entire chart.

But what you don't know is that Earth is located at the 1 AU point on that chart, which is where some of those blue dots overlap, making the Earth, the Moon, and Mars a part of the actual asteroid belt. A part of the population of bodies they consist of. Jupiter is located at 5.2 AUs from the son, by the way AUs mean astronomical units and they refer to the average distance between the Sun and the Earth, which makes Jupiter also a part of this giant loose belt of objects. Well since Jupiter is by far the largest by all acounts, that therefore demotes the Earth and Mars from being identified as planets.

Now if they were speaking of... object that orbit around Pluto, then that is a bit different.

But lets look at the difference between Charon and Pluto and that would explain why Charon and Pluto are in a biplanetary system rather than in a monoplanetary system.

Perhaps we should consider using the 'by far the largest body in its population of bodies" citation in association with satelites to see why kind of a planetary system we are looking at.

This would mean we would have to look at Nix and Hydra and see where they would fall in at with Pluto and Charon.

But considering how tiny Nix and Hydra are, we can safely assume that Pluto and Charon are planets that encompass the same satelites or moons. And Pluto is still considerably larger than Charon with Nix and Hydra combined. So it is still a planet upon that definition.

Some people just need to get their heads of the box so they can think without being ridiculed for their stupidity.

[edit on 18-8-2006 by Timeseer]

I don't mind Charon being called a planet, but if the IAU settles for this, then I will be extremely annoyed if our own Moon is not similarly defined. The situation is different, but I find it astonishing that an object that is in both Earth orbit and solar orbit (and is of considerable size) is not going to be included in the updated list.

I really can't understand this. It would only require a slight modification of the proposed definition, since our Moon is the only large planetary satellite in the Solar System that has an orbit of this nature.

Originally posted by Mogget
I don't mind Charon being called a planet, but if the IAU settles for this, then I will be extremely annoyed if our own Moon is not similarly defined. The situation is different, but I find it astonishing that an object that is in both Earth orbit and solar orbit (and is of considerable size) is not going to be included in the updated list.

All planetary moon are in the Solar Orbit...

All moon orbit the sun while they orbit the planet they correspond to...

Originally posted by Mogget
I really can't understand this. It would only require a slight modification of the proposed definition, since our Moon is the only large planetary satellite in the Solar System that has an orbit of this nature.

Well maybe the Moon should be given a special lunar definition, just as Pluto should be given a special planetary definition.

If the Earth orbited around the Moon, as Pluto orbits around Charon, then the Moon should be considered a Planet. But since it stil orbits around the Earth as it orbits around the Sun, it is a celestial satelite (aka moon).

All planetary moon are in the Solar Orbit...

If you want to be pedantic, then they do indeed move around the Sun with their respective planetary companions. However, the orbit of our Moon is different to that of any other large planetary satellite in the Solar System. That's because the gravitational pull of the Sun acting on it is roughly twice that of Earth. That means that it can be argued that the Moon is actually in solar orbit as well as Earth orbit.

Every other large satellite in the Solar System experiences a stronger gravitational force from it's parent planet than it does from the Sun. Only some of the outer satellites of Jupiter, Saturn, Uranus, and Neptune are pulled more strongly by the Sun than they are by their planetary parents, and these can be ruled out as planets because they are too small and irregular.

That makes the Moon unique.

If the Earth orbited around the Moon, as Pluto orbits around Charon, then the Moon should be considered a Planet.

Don't make the mistake of thinking that the Earth doesn't orbit the Moon, simply because the centre of gravity is within the body of Earth itself.


[edit on 20-8-2006 by Mogget]

Originally posted by Mogget
Don't make the mistake of thinking that the Earth doesn't orbit the Moon, simply because the centre of gravity is within the body of Earth itself.

And the center of gravity of every other planet and its moon(s) lies within the parent planet. The difference with Pluto/Charon is that the center of gravity is outside of both bodies.

And the center of gravity of every other planet and its moon(s) lies within the parent planet. The difference with Pluto/Charon is that the center of gravity is outside of both bodies.

Absolutely, and that does make the Pluto-Charon system unique. It's just that I also consider the Earth-Moon system to be unique, but for a different reason

Damn, why can't we just settle for eight major planets, and demote Pluto to a "KBO" ? It would make far more sense.

Originally posted by Mogget

And the center of gravity of every other planet and its moon(s) lies within the parent planet. The difference with Pluto/Charon is that the center of gravity is outside of both bodies.

Absolutely, and that does make the Pluto-Charon system unique. It's just that I also consider the Earth-Moon system to be unique, but for a different reason

Damn, why can't we just settle for eight major planets, and demote Pluto to a "KBO" ? It would make far more sense.

Hahahaha Sense! ahahaha These people dont want sense, they want to make things as complicated as possible. Theyre like astrocrats, every new planet must fill out the forms and get two references from naturalized planets, and get the appropriate stamps. After this they become a guest planet and if they complete three years of orbit they will be put on a waiting list where new planets are selected at random on thursdays and alternate tuesdays omitting bank holidays.

The new system is ridiculous. All they have to do is demote Pluto from "planet" to "KBO". That would leave us with eight major planets, and everything else takes care of itself. How difficult can that be ?

Oh, and I've sent an e-mail to the IAU about this. I doubt that it will wake those idiots up, but you don't get anywhere unless you try.



[edit on 20-8-2006 by Mogget]
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mod edit censor circumvention

[edit on 22-8-2006 by masqua]

Originally posted by Mogget

If you want to be pedantic, then they do indeed move around the Sun with their respective planetary companions. However, the orbit of our Moon is different to that of any other large planetary satellite in the Solar System. That's because the gravitational pull of the Sun acting on it is roughly twice that of Earth. That means that it can be argued that the Moon is actually in solar orbit as well as Earth orbit.

Every other large satellite in the Solar System experiences a stronger gravitational force from it's parent planet than it does from the Sun. Only some of the outer satellites of Jupiter, Saturn, Uranus, and Neptune are pulled more strongly by the Sun than they are by their planetary parents, and these can be ruled out as planets because they are too small and irregular.

Gravitation force should have to imply with the definition of a moon. A moon is simply a celestial object that orbits about another object that isn't a star without that object orbiting around it.

Originally posted by Mogget
That makes the Moon unique.

Yes a unique moon, but still a moon.

Originally posted by Mogget
Don't make the mistake of thinking that the Earth doesn't orbit the Moon, simply because the centre of gravity is within the body of Earth itself.


[edit on 20-8-2006 by Mogget]

I'm sorry but if it clearly isn't moving about in orbit around the moon than it is in orbit around the moon and thus the Moon is not a planet, it is a moon.

But don't worry in a few billion or hundred million years... the moon will eventually be considered a planet. If it still exists during that time of course.

[edit on 22-8-2006 by Timeseer]

I gave this problem further consideration, and then came up with the following......

A planet should be defined as "any object that is massive enough to gravitationally dominate the region of space in which it resides".

That sounds like an excellent starting position to me. It would instantly reduce the number of known major planets to eight, since Pluto does not gravitationally dominate anything outside of its three satellites. It would also rule out the promotion of Ceres, Charon, and 2003UB313 to planetary status (which is something that should be avoided at all costs).

In my humble opinion, of course

I'm sorry but if it clearly isn't moving about in orbit around the moon than it is in orbit around the moon and thus the Moon is not a planet, it is a moon.

The Earth and Moon orbit each other around their common centre of mass, just like every other two body system in the known universe !

[edit on 22-8-2006 by Mogget]

Originally posted by Mogget
I gave this problem further consideration, and then came up with the following......

A planet should be defined as "any object that is massive enough to gravitationally dominate the region of space in which it resides".

That sounds like an excellent starting position to me. It would instantly reduce the number of known major planets to eight, since Pluto does not gravitationally dominate anything outside of its three satellites. It would also rule out the promotion of Ceres, Charon, and 2003UB313 to planetary status (which is something that should be avoided at all costs).

In my humble opinion, of course

When you think of the Asteroid Belt, you are oftenly thinking of the main asteroid belt between Mars and Jupiter. But the true asteroid belt consists of object between the Earth and Jupiter. Actually it sort of bypasses Jupiters and Earth's orbits by a considerably degree.

This is all a region of space that the Moon, Earth, Mars, and Jupiter Share.

Now which object dominates this region of space in terms of mass? It shouldn't be that hard to guess with something as huge as a thousand or so Earth.

Well since Jupiter dominates the entire area that it resides in, which is the true asteroid belt. That therefore makes both the Earth and Mars as being something else other than planets. Thanks for clarifying that one up bub...

I'm sorry but if it clearly isn't moving about in orbit around the moon than it is in orbit around the moon and thus the Moon is not a planet, it is a moon.

The Earth and Moon orbit each other around their common centre of mass, just like every other two body system in the known universe !

Actually the Earth doesn't orbit around a center mass other than the Sun (which is in an eliptical orbit), the moon orbits around the Earth's center orbit of Mass. Just as Jupiter's moons orbit around Jupiter's center orbit of mass.

[edit on 22-8-2006 by Timeseer]
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Attempted to unravel quoting
Hope I got it right

[edit on 22-8-2006 by masqua]

[edit on 22-8-2006 by Timeseer]

Actually the Earth doesn't orbit around a center mass other than the Sun (which is in an eliptical orbit), the moon orbits around the Earth's center orbit of Mass. Just as Jupiter's moons orbit around Jupiter's center orbit of mass.

Anyone else care to try ?

Originally posted by Mogget

Actually the Earth doesn't orbit around a center mass other than the Sun (which is in an eliptical orbit), the moon orbits around the Earth's center orbit of Mass. Just as Jupiter's moons orbit around Jupiter's center orbit of mass.

Anyone else care to try ?

Please reframe from making one line responses or you will be fairly warned by moderators.

By the way were you really looking for a different response?

Originally posted by Timeseer
Please reframe from making one line responses or you will be fairly warned by moderators.

Please leave the thread direction and moderation to the ATS Staff and Moderators.

God I hate beuaracy, if people could just relize that the definition is irrelevant things would be much better.