POLL: Should Pluto's Planet Status Be Revisited?

[PeterMarcus]

Not true at all. Pluto was the first trans Neptunian object discovered, and has eternally secured it's place in history. It hasn't been demeaned at all; in fact it is the first of a whole new class of objects.

Just like the first radioactive elements discovered were an entirely new class that expanded the science of chemistry and physics. But, since they were demonstrably different than non-radioactive elements, they couldn't actually be called elements. They, like, changed into different elements and everything.

 

[MeteorWayne]

The IAU had no right to lay down the law about anything.

You do realize look like kind of a child who has to shout, instead of conducting a reasoned argument, right?

 

[MeteorWayne]

Not true at all. Pluto was the first trans Neptunian object discovered, and has eternally secured it's place in history. It hasn't been demeaned at all; in fact it is the first of a whole new class of objects.

Just like the first radioactive elements discovered were an entirely new class that expanded the science of chemistry and physics. But, since they were demonstrably different than non-radioactive elements, they couldn't actually be called elements. They, like, changed into different elements and everything.

Uhhh, you do realize that many natural elements (Uranium, Radium, to mention 2 of dozens) are naturally radioactive and change into different elements as they decay, right?

:roll:

 

[PeterMarcus]

Uhhh, you do realize that many natural elements (Uranium, Radium, to mention 2 of dozens) are naturally radioactive and change into different elements as they decay, right?

Yes, and that was my point. They're different, they were a drastically, shockingly new class of matter, and yet they're still elements.

I'll refrain from sarcasm as I botched it.

Sure there are different classes of planets. Gas giants, dwarf planets, classical planets, whatever. They're unique and different, but can be grouped as well. So: How many planets are there in the solar system? Any answer that equals 8, to me, is the same as saying that the number of elements only equals the non-radioactive ones. Or the non-metals. Or only the solids. Or not including those weird single-atom noble gas thingies.

 

[RJEvans]

I don't buy this argument that Pluto does not fit in with the rest. Hypothetically, what if there is a Pluto-like object the size of Earth that has an inclination of 90 degrees. Is that not a planet too? Whose to say it is not planet because its composition is like Pluto or it does not orbit with the classical eight. It's a ridiculous argument that a Planet should not be a planet because it does not orbit within the plane of the rest of the planets or its composition is too different from that of a rocky planet or gaseous planet. Lets keep the definition of a planet simple, then have classifications of different types of planets, such as a star.

Let's see, it's now a dwarf planet, a different classification of planet, just as a dwarf star is a different classification of star. It's what you asked for. So what's your beef?

MW

And therefore a planet. The Sun is a yellow dwarf star, but we still call it a star because by definition it is a star. You are outright claiming that Pluto is not a planet. Your claim is that Pluto is not a planet because of its "mass, orbital inclination and eccentricity and it's resonant orbit with Neptune". That is completely a utterly absurd. There is no universality in your definition, and it's prone to arbitrary benchmarks. Is everything above 0.01 the Mass of Earth a planet and everything below not? Is everything above 1500km in diameter a planet and everything under it a dwarf planet or Plutino? Is everything with an inclination above 15 degrees a dwarf planet or Plutino and everything below it a planet? It's complete and utter nonsense.

 

[ISS_Fan]

There is a superb article about this under "Dwarf Planet" in Wikipedia. If you read the section "Orbital Dominance", you will see how astronomers are using a very precise and mathematical way to make classification distinctions. It is based upon Steven Soter's Mu parameter to determine to what degree objects have cleared the neighborhood of their orbital space. The eight planets have a Mu that ranges from a low (Neptune @ 2.4 * 10^4) to a high (Earth @ 1.7 @ 10^6) of approximately two orders of magnitude. But the difference in Mu between the lowest planet and the greatest dwarf planet (I wished the IAU had accepted the recommended term "planetoid" instead.) is FIVE orders of magnitude (Neptune @ 2.4 * 10^4 versus Ceres @ 3.3 * 10^-1). And all five of the currently designated dwarf planets (Ceres, Pluto, Haumea, Makemake, Eris) have Mu values that are only about one order of magnitude apart (Ceres @ 3.3 * 10^-1 to Haumea and Makemake @ 2.0 * 10^-2). So, there really are two distinctly different and widely separated clusters by this metric.

 

[PeterMarcus]

ISS_Fan

I'll reluctantly buy that for Ceres (even though I could perhaps argue a Jupiter influence), but for the rest, you're talking about a huge, huge difference in orbital area vs. size of the body -- the orbital area is orders of magnitude greater than, say, the orbit of Mercury. If Mercury was located in the same crowded and extremely low-speed orbital space of Makemake, would the Mu for Mercury be the same as it is snug up to the sun? Would Mercury be demoted to a planetoid if it was in the same orbit as Makemake?

We're also talking of an n=1 when it comes to solar systems. Many of the new exoplanets discovered don't fit into a neat solar system model. Will we be applying the same terms for planets in star systems outside our own?

Again, I could make an argument about what it means to be an element. Show me a kilo of copper and a kilo of radium. I'll come back in 1601 years, and measure how much copper and how much radium is there. Should radium be considered an element? It's clearly not as stable as copper.

 

[laurele]

I cannot personally answer this poll because it is fundamentally flawed in the way it limits possible responses. Yes, Pluto's planet status should be revisited, but so should Eris's. Both objects are large enough to be in hydrostatic equilibrium and orbit the Sun. The category of dwarf planet was created by Dr. Alan Stern to indicate a third class of planets, objects large enough to be rounded by their own gravity but not large enough to gravitationally dominate their orbits. Stern never intended for dwarf planets to not be considered planets at all. In astronomy, dwarf stars are still stars, and dwarf galaxies are still galaxies. In each case, the dwarf category is the most numerous, and this is likely the case with dwarf planets as well.

Please revise this question to allow an option giving planet status to both Pluto and Eris.

 

[bdewoody]

As usual Doublehelix worded his poll in such a way that none of his choices were acceptable. But since I feel that Pluto deserves planetary status I selected his first option. Of course Pluto is what it is and no matter how many committees change what they want to call it, it will remain the same. What they should be looking at here is what the definition of a planet should be. Not just for our solar system but also for all the other stars that have "planets" orbiting them.

 

[MeteorWayne]

PeterMarcus,

Much as the mu parameter described above, if you look at the masses of the planets, there is a steady drop until you reach the Pluto/Ceres/Eris class, where there are dozens of such tiny objects (with many more to be found) I had a great series of charts for all these paramaters which unfortunately were lost in one of the software changes, and in my smoked hard drive and backup drive.

 

[Jeroen94704]

Grouping objects together into categories can be a useful tool for science. It doesn't convey any kind of status and it is not a judgment about the value of an object. As such, it is completely irrelevant whether Pluto is classified as a planet, dwarf planet, Kuiper Belt Object or whatever. Pluto is a body in the solar system with a specific set of characteristics, and that's it.

Since this was not an option in the poll, I didn't answer the question

 

[Gerrit_smit_br]

We can do two things, or wel call everything that circles the sun a planet, or we specify a little bit better. I prefer to specify. We have rocky planets, Mercury, Venus, Earth, Mars, we have gas giants, we have rocky outher 'bodies', we have rocky inner 'bodies' ( asteroids ). Everybody knows that you cannot classify Jupiter in the same group as Pluto. That's simple. Let's not get emotional about this. Let's look at it in a scientific way. It will not change the truth. What's in a name?

 

[RikF]

What's the purpose of having a definition of the concept of 'planet'? What is it supposed to be used for?
For non-educated general population perhaps the definition 'planet' would be best, whereas for scientists
there might be a use for better classification, perhaps type1 planets (rocky planets), type2 planets (gas giants), type3 planets (smaller with tilted and/or ecsentric orbits) and so on.

Pluto orbits our sun, it hass mass enough to be sferical, it's gravitation hold a moon. Theoretically, it could have an atmosphere and life.

If Pluto had the same size as earth and were at the same distance from the sun as earth and had intelligent
beeings on it but all else the same as now, would it then qualify for 'planet'?

For now i consider it to be a planet since i don't see any added value in using another definition for it.

 

[DastardlyDan]

I think that the definition of a planet should be broader, instead of narrower. Basically, anything with enough mass to reach hydrostatic equilibrium, yet not of enough mass to ignite any kind of nuclear reaction in it's core, should be classified as a planet. However, there can be many subclasses of planets. Gas giants, terrestrial planets, dwarf planets, etc. We have different classes of stars, but they are all stars...so why not go the same route with planets? It seems like a more scientific approach to me.
This also allows us to work with any future discoveries that don't fit any current definitions...we just create a new subclass of planet.

 

[Sehala]

I don't think that a world must orbit in the same plane as the other planets, or in the plane of the star's rotation, to be a planet. Suppose, early in a system's development, you have a Neptune-sized planet that gets tossed into a highly inclined orbit by a passing body (an unrelated star or wandering brown dwarf). Is that Neptune-sized world no longer a planet?

A while back, Space.com reported on a forming system in which the inner part of the debris disc orbits it's star in one direction (with the star's rotation), but the outer part orbits in the opposite direction to the star's rotation (inclined 180 degrees from the inner). If planets form, are the ones orbiting opposite to the star's rotation not planets?

A number of exosolar "hot jupiters" have been discovered that orbit opposite to their star's rotation, or are in highly inclined orbits relative to the star's rotational plane. Are these "hot jupiters" not planets?

 

[brokndodge]

Log my refusal to vote as none of the options applies. The answer to the question is in the name of the definition: dwarf PLANET. I understand that requires school children to memorize the names of perhaps a dozen planets at this point, but it is still the case. Maybe, once we have identified 3 or 4 dozen dwarf PLANETS, the children will no longer be required to memorize all their names.

Seems to me the IAU has set the definition then refused their own classification. By name, a dwarf PLANET would still be a planet. I do like the suggestion of adding the binary dwarf planet classification tho. And yes, Pluto and Eris are both planets. Perhaps Charon is too, which would make Pluto-Charon binary. I guess that would be determined by the actual orbits of those two. Do they orbit each other or does Charon orbit Pluto? Wikipedia has the answer to this one: http://en.wikipedia.org/wiki/Moons_of_Pluto Charon does orbit Pluto, however, the barycenter is outside of Pluto. Seeming to indicate a binary behavior. Thus Pluto-Charon could be considered a binary dwarf planet system. Although the other two moons seem to orbit Pluto rather than the binary pair (my speculation, those smarter than me can challenge that statement).

Further complication of the subject is in Pluto's other two moons. So we now have a "not-a-planet" with (count them with me) 3 total moons. Seems like a planet to me.

 

[elroy_jetson]

I didn't vote in the poll because I didn't like any of the listed answers. While I would have preferred Pluto remained listed as a planet (perhaps with an asterisk explaining Pluto's discovery, and subsequent discoveries leading to the "dwarf" class of planetary bodies), over two years have passed since the IAU chose to change Pluto's status. There's really no point in re-changing Pluto's status.

 

[bdewoody]

I think that the definition of a planet should be broader, instead of narrower. Basically, anything with enough mass to reach hydrostatic equilibrium, yet not of enough mass to ignite any kind of nuclear reaction in it's core, should be classified as a planet. However, there can be many subclasses of planets. Gas giants, terrestrial planets, dwarf planets, etc. We have different classes of stars, but they are all stars...so why not go the same route with planets? It seems like a more scientific approach to me.
This also allows us to work with any future discoveries that don't fit any current definitions...we just create a new subclass of planet.

This is basically what I said. And is the IAU using their solar definition of what is a planet with regard to other stars?
I believe in the KISS principal. Keep It Simple Stupid

 

[jsmoody2]

This is ridiculous. Pluto is just so obviously a Kuyber Belt object that it makes debate on the subject ludicrous. It was mis-named for decades, let's not go back there...

 

[bdewoody]

This is ridiculous. Pluto is just so obviously a Kuyber Belt object that it makes debate on the subject ludicrous. It was mis-named for decades, let's not go back there...

Heck you can't even spell it so your credibility is shot. What makes you the final arbiter of what the definition of a planet is. Pluto can be a Kuyper belt object and still be a planet. They already call it a minor planet or planetoid.

 

[jsmoody2]

"Heck you can't even spell it so your credibility is shot. What makes you the final arbiter of what the definition of a planet is. Pluto can be a Kuyper belt object and still be a planet. They already call it a minor planet or planetoid."

Oh, so then YOU'RE the final arbiter. Excuuuuse me... But if it's a Kuyper Belt object and a planet, then we'd have to make all the Kuyper Belt objects planets. The current definition is perfectly fine. But if you think you know more than the Astronomical Union then maybe you should contact them and tell them they don't know what they're talking about. (You also need to get over your anal obscession with typo errors).

 

[jsmoody2]

Not sure what the fuss is all about....

If it's round and it doesn't burn, it's a planet. What sort of planet? Gas giant? Terrestrial? Water world? Ice planet? Dwarf? We'll keep adding to the categories as we understand more about exoplanets.

As for the orbital resonance with Neptune, I don't think that really applies - many planets we'll discover will have similar properties, as of course do moons. Speaking of which, I think that we should worry more abouts moons right now - they're far more varied. Is Phobos a moon? I doubt it.

If it's round and doesn't burn??? Then all the astroids and coments and other space debris will have to be classified as planets.

 

[MeteorWayne]

"Heck you can't even spell it so your credibility is shot. What makes you the final arbiter of what the definition of a planet is. Pluto can be a Kuyper belt object and still be a planet. They already call it a minor planet or planetoid."

Oh, so then YOU'RE the final arbiter. Excuuuuse me... But if it's a Kuyper Belt object and a planet, then we'd have to make all the Kuyper Belt objects planets. The current definition is perfectly fine. But if you think you know more than the Astronomical Union then maybe you should contact them and tell them they don't know what they're talking about. (You also need to get over your anal obscession with typo errors).

When you spell it wrong 3 times, it's not a typo. It's Kuiper belt.

And I'm on the "it ain't a planet" side, and I was so long before the IAU weighed in. IMHOWIOCR, it's a KBO and a Plutino (object in 2:3 resonance with Neptune) of which there were 27 a few years ago, last time I did a full check. I'm sure it's far higher than that now.

MW

 

[Sycamorefan]

I always assumed the reasons Pluto was demoted in status were the following: 1. Pluto was mostly likely a rogue moon escaped from Jupiter or Saturn. 2. It's orbital sequence could mean it's now a moon of Neptune or will be in the future. 3. Wouldn't Pluto be better classified as a Kuiper Belt Object? :?:

 

[Skyskimmer]

I think that the definition of a planet should be broader, instead of narrower. Basically, anything with enough mass to reach hydrostatic equilibrium, yet not of enough mass to ignite any kind of nuclear reaction in it's core, should be classified as a planet. However, there can be many subclasses of planets. Gas giants, terrestrial planets, dwarf planets, etc. We have different classes of stars, but they are all stars...so why not go the same route with planets? It seems like a more scientific approach to me.
This also allows us to work with any future discoveries that don't fit any current definitions...we just create a new subclass of planet.

This is basically what I said. And is the IAU using their solar definition of what is a planet with regard to other stars?
I believe in the KISS principal. Keep It Simple Stupid

Strongly agreed this whole planet thing is getting sidetrack. The word planet is outdated it was a greek word, what's with keeping a 2000 year old word that has become pointless. I think the issue is in education to children, we all know that we learned the most important thing in the solar system were planets, and that there are 8 earthballs and a bunch of little rocks. This is the problem the label planet creates, we automatically think earth like. Yet in human terms europa is the most earth like, in term of chances of liquid water and it's a moon, just the same Io is vocanic like earth still a moon and mars is not. The point is there equally relevant. Yet planet skews this, i think it's far more scientific to call them all planetoids. Have no "planet. But gas jovials, terriestials(again I don't think mercury fits,) and dwarf planets (anything that is round). Even the moon should be consider a dwarf planet.

My biggest pet peeve is were using history as influence on the decision. It's like calling europe when it's been long proven it's a subcontinent.