So Pluto is a planet!?

[Camacha]

Every classification is arbitrary. Things in nature don't come with labels on them. People classify them.

My former statements remain true - any classification is going to have cases that are right on the edge, but the third requirement for planets makes that edge blurry. I do not really care that we might end up with 250 planets. If that is what's the case, then that is what's going on. We could still teach children about the eight major planets, or 10, or 20.

Edited October 3, 2014 by Camacha

[No one]

We had this argument a very long time ago when the asteroid belt was discovered and decided that Pluto was not a planet. I don't see why we needed to have it again when we actually discovered that Pluto wasn't a planet.

Personally, I think the definition is too permissive. We need to find a way to exclude Mercury. And possibly Mars. Venus and Earth are cool, they can stay. And then let's put the gas giants in their own category. And then we end up with 2 planets. Umm....

We should do the following:

Extend the definition of "planet" to include what are currently dwarf planets.

Subdivide "planet" into the following:

Dwarf Planets* (Ceres, etc.) Lame Planets** (Mercury, Mars), Earthlike Planets (Earth, Venus), Gas Giants* (Jupiter, Saturn, Uranus, Neptune)

*May need subdivisions

**Ok so maybe we could give them a different name. But I like "Lame Planets", I mean, they are pretty lame.

And then we need to take a look at the word "Moon". What the heck are Ganymede and Euporie doing in the same category?

[Superfluous J]

There was a time when Ceres was considered being a planet. Does anyone nag about Ceres? No. Why? Probably because it wasn't discovered by an American. Yeah, sorry, but that's the core of the problem. Nationalism. Plain and simple. Boo-hoo.

The mere concept that any even remotely significant fraction of Humanity would know that Pluto was discovered by an American rules out this idea. Especially Americans wouldn't know that. Heck, even I wasn't 100% sure of it.

Far more likely it's because Ceres didn't share a name with a Disney character.

[benkh]

I,personally, think that Science isn't a kind of democracy where you can vote to what you think is right , but a system where Research, Theorism and clever people define what is right

[stupid_chris]

Well it's a dwarf planet so it is still a planet.

There there Pluto, you will always be a planet to me...

It's estimed there are a few hunderd bodies in rotation around the sun the size of Pluto or bigger.

If we all call them planets, the term is becoming extremely generic. At that point we'll want a term to differentiate the big important ones from the small icy far away "planets". Thinking it this way, you realize we already did that.

Pllanets need:

A) To be

[Camacha]

I,personally, think that Science isn't a kind of democracy where you can vote to what you think is right , but a system where Research, Theorism and clever people define what is right

So scientists voted on what they felt was right

If we all call them planets, the term is becoming extremely generic. At that point we'll want a term to differentiate the big important ones from the small icy far away "planets". Thinking it this way, you realize we already did that.

I feel this is the whole issue. It is a kind of geocentric thinking where everything near us, or things we can easily see, is important and other things are not. The Oort cloud likely makes up a relevant part of our solar system and we need to get used to that.

Call them innies and outies, for all I care.

Edited October 3, 2014 by Camacha

[benkh]

So scientists voted on what they felt was right

Well yeah, but scientists do, not the general public

[Camacha]

Well yeah, but scientists do, not the general public

That is just shifting the problem to a smaller group. You were right initially, and what needed to be done is not what they did.

[No one]

I,personally, think that Science isn't a kind of democracy where you can vote to what you think is right , but a system where Research, Theorism and clever people define what is right

But this isn't science, it's language.

[Lunaran]

Say we had a system of taxonomy for living things that divided them into plants and animals. If it breathes and moves around it's an animal, and if it grows out of the ground it's a plant. Also, somebody once found a mushroom, which everyone immediately could tell was unlike the other plants, but, hey, it still grows out of the ground. It's a strange and different plant, but it's a plant. What else would it be?

Say this is fine with everyone for like eighty years.

Then say that, after all that time, we finally start to really actually look around in forests and we discover, wow, there's all kinds of these little weird fungusy things out here. And, they're all similar to each other in exactly the ways that mushrooms are different from all other plants. We would then conclude that there's a whole category for fungi that we missed, because our previous classification was borne of ignorance and incomplete information.

It would be weird if people complained about this. Wouldn't it?

Wouldn't it just be counter to all rational thought if people all whined and shouted "But I liked it when mushrooms were plants! What do you know, anyway? Scientists. Why can't we still just classify it as a plant anyway? I don't care what you call them, a mushroom will always be a plant to me!" and they had tshirts and bumper stickers printed up that said "WHEN I WAS YOUR AGE A MUSHROOM WAS A PLANT" and when you tried to explain to them about the whole world of fungi out there in the woods they didn't listen?

Wouldn't those people seem kind of like ... you know ... morons?

[Camacha]

Wouldn't it just be counter to all rational thought if people all whined and shouted "But I liked it when mushrooms were plants! What do you know, anyway? Scientists. Why can't we still just classify it as a plant anyway? I don't care what you call them, a mushroom will always be a plant to me!" and they had tshirts and bumper stickers printed up that said "WHEN I WAS YOUR AGE A MUSHROOM WAS A PLANT" and when you tried to explain to them about the whole world of fungi out there in the woods they didn't listen?

You're missing the point. They are now calling it mini plants, despite the fact that the classification has nothing to do with size. Does that not sound like a silly thing to do?

The (or at least my) objections have little to do with what was and more with what is.

[metaphor]

My former statements remain true - any classification is going to have cases that are right on the edge, but the third requirement for planets makes that edge blurry. I do not really care that we might end up with 250 planets. If that is what's the case, then that is what's going on. We could still teach children about the eight major planets, or 10, or 20.

The edge of objects being "round" is a lot blurrier than the edge of objects which have or have not cleared their orbit. The latter is a very sharp edge, there's no question of what side of it every planetary body in the solar system lies on. By any reasonable measure of "clearing the orbit", the planets differ by at least 5 orders of magnitude from the dwarf planets (and any other small bodies).

(Also, dwarf planet is a pretty confusing name, they should have named that category something different, like planetoid.)

Edited October 3, 2014 by metaphor

[Camacha]

The latter is a very sharp edge, there's no question of what side of it every planetary body in the solar system lies on. By any reasonable measure of "clearing the orbit", the planets differ by at least 5 orders of magnitude from the dwarf planets (and any other small bodies).

That only strengthens my point - the definition seems written to be applicable to our solar system at this moment, which is a horrible approach. As soon as you start applying it to earlier versions of our system or other systems the wheels will come flying off. It is written to apply to our current solar system of a star with 8 bodies and that seems an odd way of dealing with the issue.

Also note that one of the creators of the criterium also sees trouble, stating "If Neptune had cleared its zone, Pluto wouldn't be there".

Edited October 3, 2014 by Camacha

[metaphor]

That only strengthens my point - the definition seems written to be applicable to our solar system at this moment, which is a horrible approach. As soon as you start applying it to earlier versions of our system or other systems the wheels will come flying off. It is written to apply to our current solar system of a star with 8 bodies and that seems an odd way of dealing with the issue.

Also note that one of the creators of the criterium also sees trouble, stating "If Neptune had cleared its zone, Pluto wouldn't be there".

Neptune did clear its zone. Pluto's mass is about 0.01% of Neptune's mass, which is insignificant. Not to mention it was forced into a resonant orbit by Neptune, along with other KBOs.

The definition is written to be applicable to our solar system, because it's the only one for which we have any data regarding the existence of small bodies. Every single planetary object discovered so far around another star is clearly a planet, with a Stern-Levinson parameter greater than Mars's (which you can calculate from mass and semimajor axis).

At least in our solar system, there is a physical reason for which there exists a clear dividing line, and it has to do with the way planets form. It's not known so far if there is such a clear dividing line between planets and small bodies in other systems, since we don't have any data. If we find that not to be the case, we'll probably revise the classification.

[Albert VDS]

The best in indication of why Pluto shouldn't be a planet is that if you move it closer to the Sun it would grow a tail like a comet.

[magnemoe]

The best in indication of why Pluto shouldn't be a planet is that if you move it closer to the Sun it would grow a tail like a comet.

So would anything if put close enough

http://themhpe.deviantart.com/art/Poor-Pluto-55646689

[Albert VDS]

So would anything if put close enough

That would mean everything is a comet? See that's why we categorize everything, it stops us from putting everything in one group and gives us a way to communicate better about it.

Also a planet wont loose material as fast as a comet.

And about the above picture: Poor little Pluto is way too big(all of the planets have the wrong size relative to each other).

[Superfluous J]

And about the above picture: Poor little Pluto is way too big(all of the planets have the wrong size relative to each other).

Also, planets don't have eyes and noses in reality.

[Red Iron Crown]

Also, planets don't have eyes and noses in reality.

Also, they are not nearly that close together.

[N_las]

Also, they are not nearly that close together.

Also, there aren't giant letters in space, spelling "POOR PLUTO".

[magnemoe]

That would mean everything is a comet? See that's why we categorize everything, it stops us from putting everything in one group and gives us a way to communicate better about it.

Also a planet wont loose material as fast as a comet.

And about the above picture: Poor little Pluto is way too big(all of the planets have the wrong size relative to each other).

Any smaller outer system bodies would get a tail if put in earth orbit at least unless mars sized or larger as the cold let it freeze gas who would escape.

Then I thought that putting anything other than rocks very close would give this results, has some hot Jupiters with tails.

And the cute picture is a cartoon and uses cartoon sizes, a cat in a cartoon is larger than an mouse but not 8 time larger.

[NASAFanboy]

I'd rather just reclassify Pluto as a planet, then plug my ears to all criticism of this decision.

Probelm solved?

[Fingal]

So the Moon, Ganymede and Titan are planets¿

I trained as a geologist, so from that perspective it's difficult to see how they aren't.

[KerikBalm]

What if we placed limites on the inclination?

Say we define a range of inclinations which include 95% of the mass of objects orbitin the sun.

Or... since the sun rotates (right?), we say +/- 5 degrees from the sun's equatorial plane.

Outside of that range... you can at best be a planetoid, not a planet.

I think dwarf planet isn't as good of a name as "planetoid", but it seems they also wanted a group "minor planets" (which actually includes all the asteroids...)

The clearing the orbit thing is related to size, so I can see where "dwarf" comes in, but if you put Earth in the orbit of Eris, it wouldn't clear the orbit either.

Clearly the orbit is important, its why we'd consider pluto for planet status, but not the moon.

So... why not inclination based definitions too?

[m4v]

*Raises hand.

Like I said, the current situations seems rather arbitrary, so let's include all the roundy floaty things and be done with it. It reflects the true nature of our solar system much more accurately too, as it is a lot less empty than those 9 big balls we generally take it to be.

Your complaining seems petty to me, they're still planets, dwarf planets, which is very accurate considering their relative size compared to the other 8. And even if we go and call everything a planet, people would still separate them, since there's a clear distinction between the 8 planets and the dwarf ones (being mass, orbit), and nobody wants to learn the names of hundreds of them. They would say something like "a solar system with 8 major planets" or something like that.

I don't think it's really nationalism, it's probably plain old conservationism (or whatever the concept behind being conservative is called).

Maybe people also objected when Ceres was demoted, but much less due to the lack of fast communication like the internet.

Is really just nationalism, the states where Pluto's discoverer was born or lived passed resolutions that made it back a planet. Nobody made a fuss about Pluto being a dwarf planet in all the talks the observatory of my city gave, this is really just an issue for the US.