One Astronomer's Quest To Reinstate Pluto As a Planet

sarahnaomi writes: Most of us grew up believing that tiny, distant Pluto was the outermost planet in our solar system. Then, one day, the scientific powers that be decreed that it wasn't. But it seems the matter is far from settled. David Weintraub—who describes Pluto's exile as a stunt organized by a "very small clique of Pluto-haters"—would have the dwarf world rejoin the ranks of our Solar System's fully-fledged planets today. But solid evidence that Pluto deserves the title may come in July, when NASA's New Horizons spacecraft slingshots around the icy rock and sends us back a detailed picture of its composition. Pluto's planethood was revoked by majority vote on the final day of the 2006 IAU conference. Over 2,500 astronomers attended the meeting throughout the week, but only 394 votes ultimately decided Pluto's fate: 237 in favor of demoting the planet and 157 against.

Comments

And still

[modmans2ndcoming]

Pluto does not fit the definition of a planet.

Re:And still

[WyldPhyr]

This is stupid. When the IAU conference redefined Pluto, they didn't "demote" it, they simply reclassified it to more accurately suit it.

Re:And still

[GrumpySteen]

Neither does Jupiter. There are about 100,000 trojan asteroids in Jupiter's orbit, so it fails the third criteria; "cleared the neighbourhood around its orbit."

In fact... Earth, Mars, Jupiter and Neptune all fail to meet that criteria.

The definition of "planet" is a fucked up mess that a small group of astronomers threw together with the intent of classifying Pluto as not-a-planet without really thinking it through.

Re:And still

[Anonymous Coward]

And the mass of those asteroids is negligible compared to the mass of the planet in question. If you eliminate a anything that has something crossing it's orbit from being a planet, we live in a universe devoid of planets.

Jupiter, Mars, and Earth all easily outweigh those things left in their orbit so it is effectively cleared. Not true of Pluto, etc.

Re:And still

[QuasiSteve]

In fact... Most astronomers counter this opinion by saying that, far from not having cleared their orbits, the major planets completely control the orbits of the other bodies within their orbital zone.

It's a bit weird that the leading paragraph exists in both articles, while the counterpoint doesn't, but there you go.

Re:And still

[Rei]

Exactly. There are many categories of planets, including but not limited to:

  * Terrestrial planets
  * Gas giants
  * Ice giants
  * Hot jupiters
  * Superearths

And so forth. Why does the concept of another category, dwarfs, enrage people?

Really, the only categorization issue that I'm adamant about is that Pluto-Charon is called a binary. The Pluto-Charon barycentre is not inside Pluto, therefore Charon is not rotating around Pluto, the two are corotating around a common point of space between them. That's a binary.

Re:And still

[buchner.johannes]

How dare you challenge the might of Jupiter! It weighs 320 times the mass of Earth -- even if those 100,000 trojan asteroids weighed as much as its minor moons (which they don't, they are 0.0001 Earth masses according to wikipedia), it would still dominate its gravitational field by several (9) orders of magnitude.

Compare that to Pluto: Charon already weighs 10% of Plutos mass. The center of rotation in that system is not even inside Pluto.

Also, there are other criteria that apply: a planet has to be spherical due to gravitation (there is a more technical definition). Is that the case for Pluto?

Finally, you can not have 9 planets anymore. You can choose between 8 planets and 13 planets, the latter group growing every year.

Re:And still

[Jane Q. Public]

I want the definition to go back the way it was. That way, maybe we will finally get to name its companion "Goofy", rather than that dumbass Charon moniker.

Re:And still

[Anonymous Coward]

Why does the concept of another category, dwarfs, enrage people?

I think they prefer to be called Little Planets

Also losing Pluto screwed up the mnemonic:
Moving very easily Mona Jones stood under Norman's pineapples. (It's from a song)
Without Pluto what is Mona going to be standing under?

Re:And still

[mister_playboy]

Really, the only categorization issue that I'm adamant about is that Pluto-Charon is called a binary. The Pluto-Charon barycentre is not inside Pluto, therefore Charon is not rotating around Pluto, the two are corotating around a common point of space between them. That's a binary.

The barycenter of the Sun-Jupiter system lies at 1.068 solar radii, outside the Sun. Do you think they should be called a binary?

Re:And still

[Anonymous Coward]

I want the definition to go back the way it was. That way, maybe we will finally get to name its companion "Goofy", rather than that dumbass Charon moniker.

It's the price of scientific knowledge. Things change.
People born before the 1920s lived in static eternal universe and a solar system with 8 planets. You'd think they took to pitchforks when Hubble discovered the expansion of the universe and Clyde Tombaugh discovered Pluto.
We know a lot more about the solar system then when I was kid in the eighties. It doesn't disturb me that astronomers have reclassified Pluto according to new scientific data.

Re:And still

[Anonymous Coward]

"Planet" originally meant a star which moved through the constellations. The concept of size or distance or mass was utterly irrelevant. Having "categories" of planets, particularly given that there were less than a dozen examples, was a ludicrious suggestion.

It still is. There are still less than a dozen planets that can even be halfway considered observed to the point of resolved, much less understood. The idea that humans have somehow categorised these objects is as absurd as it is untenable.

There is no definition of a planet. And, given the people currently in charge of the study of them, there probably never will be.

Re:And still

[fyngyrz]

Without Pluto what is Mona going to be standing under?

Pompous asses. :)

Re:And still

[fyngyrz]

The barycenter of the Sun-Jupiter system lies at 1.068 solar radii, outside the Sun. Do you think they should be called a binary?

No. Because they aren't both stars.

Re:And still

[mister_playboy]

Jupiter emits more heat into space than it receives from the Sun.

(I agree with you, just playing devil's advocate).

Re:And still

[sumdumass]

Why does the concept of another category, dwarfs, enrage people?

It's not the concept or name that enrages people. Well, some might get pissed if you call them a dwarf and are not yourself a dwarf. It's that all the other planets you mentioned are still considered planets while somehow the dwarf planet is being used to denote that Pluto is not a planet. Instead, Pluto is the big headed cousin of a midget or some other shit now.

Re:And still

[Rei]

And if Jupiter was large enough to be a brown dwarf? Yes, of course.

Re:And still

[AK Marc]

Anyone who made that definition could just move the arbitrary line of "too small" and remove the classification of the Earth as a planet. That's part of the complaint. The rules are all completely arbitrary.

Re:And still

[AK Marc]

No, you can have 9. The definition doesn't need to be consistent, and I've seen hundreds of definitions that would include Pluto, but not the other 4 you are referencing.

Re:And still

[pjbgravely]

Pluto has always been my favorite planet, but in the end they are correct. It has the orbit of a comet and it may vent particles like a comet. Very soon we will probably know for sure.

Re:And still

[Cochonou]

You seem to have missed this peculiar characteristic of the 2006 definition of a dwarf planet: it is not a category of planets. Have a look here:

The IAU members gathered at the 2006 General Assembly agreed that a "planet" is defined as a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighbourhood around its orbit.

This means that the Solar System consists of eight "planets" Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. A new distinct class of objects called "dwarf planets" was also decided. It was agreed that "planets" and "dwarf planets" are two distinct classes of objects. The first members of the "dwarf planet" category are Ceres, Pluto and 2003 UB313 (temporary name). More "dwarf planets" are expected to be announced by the IAU in the coming months and years. Currently a dozen candidate "dwarf planets" are listed on IAU's "dwarf planet" watchlist, which keeps changing as new objects are found and the physics of the existing candidates becomes better known.

So this definition actually enrages three kinds of people:
- People who think Pluto should be classified as a planet for historical reasons.
- People who think Pluto should be classified as a planet, precisely because as you said, they are many categories of planets which are quite different (terrestrials, gas giants...).
- People who think it is gramatically incorrect for "dwarf planets" not to be "planets".

Re:And still

[ultranova]

And so forth. Why does the concept of another category, dwarfs, enrage people?

I suspect there's some kind of pissing match going on behind the scenes, and Pluto is simply being used as a proxy. That's usually the case when something utterly insignificant gets treated like it was Serious Business.

In the end, even astronomers are just humans, and can't avoid projecting their personal issues into their work.

Re:And still

[Carewolf]

Exactly. There are many categories of planets, including but not limited to:

  * Terrestrial planets

  * Gas giants

  * Ice giants

  * Hot jupiters

  * Superearths

And so forth. Why does the concept of another category, dwarfs, enrage people?

Really, the only categorization issue that I'm adamant about is that Pluto-Charon is called a binary. The Pluto-Charon barycentre is not inside Pluto, therefore Charon is not rotating around Pluto, the two are corotating around a common point of space between them. That's a binary.

I think it might be cultural. In Denmark and probably generally for Europe, I grew up with Pluto either never being mentioned as a planet or not said to be a real planet. I knew of Pluto from comic books and American media, so I always brought it up when we had any material on planets in school and Pluto was not mentioned. I was told over and over that Pluto was either not a real planet, or a planet but not like the others.

You can call dwarf planets, planets. Then we have growing number of planets in the solar systems many without proper names, that would be fun, but confusing, and they would still not be like the other planets.

Re:And still

[TheRaven64]

If Pluto is a planet, then so is Eris (which is larger), and Earth's moon (around 5 times larger than Pluto) is possibly a binary planet. Ganymede, the largest moon in the solar system, is under 3% the mass of Earth and is about ten times bigger than Pluto. There are quite a lot of moons bigger than Pluto, so would you want to classify them all as planets?

Re:And still

[donaldm]

The definition of "planet" is a fucked up mess that a small group of astronomers threw together with the intent of classifying Pluto as not-a-planet without really thinking it through.

Like it or not humans have been classifying things from the beginning of our species. Yes sometime we get it wrong or not quite right but we do try and refine our classifications using scientific principles.

Neither does Jupiter. There are about 100,000 trojan asteroids in Jupiter's orbit, so it fails the third criteria; "cleared the neighbourhood around its orbit."

That is just nit picking and is covered by the quote (see below) from your reference anyway. Basically all of that cosmic rubble (call them asteroids or chunks of rock if you will) are orbit crossing and are tiny in respect to the planet which is significantly different. None of the eight planets cross each others orbit however "Pluto" does cross Neptune's orbit which makes Pluto fall under a different criteria than what we classify as "normal planet orbital behaviour". Oh before I forget Pluto's orbital plane is different form the orbital plane of the other planets, read into that what you will.

As per your reference I quote:

In the end stages of planet formation, a planet will have "cleared the neighbourhood" of its own orbital zone (see below), meaning it has become gravitationally dominant, and there are no other bodies of comparable size other than its own satellites or those otherwise under its gravitational influence. A large body which meets the other criteria for a planet but has not cleared its neighbourhood is classified as a dwarf planet. This includes Pluto, which shares its orbital neighbourhood with Kuiper belt objects such as the plutinos.

Oh well maybe in the future Pluto will cross Neptune's orbit and Neptune will be waiting for it then the debate will be solved. Of course in a few billion years none of this will matter anyway.

Re:And still

[gomiam]

Without Pluto what is Mona going to be standing under?

Norman? The interesting part would be to know what Mona Jones was actually doing... but it still makes sense.

Re:And still

[Will.Woodhull]

It would make sense to classify the Earth - Moon as a binary planet. Life-as-we-know-it is most likely to occur in binary planet situations, where large tides are the stirring rods that keep the proto-life soups from settling into non-interactive stratifications. Creating the class of binary planet with the Earth - Moon as the prototypical first pair would help focus exoplanetary studies, and also inject new considerations into Earth science studies, such as plate tectonics, geomagnetism, possibly meteorology and climate studies, etc.

As to Pluto: Yep, its a planet. Has been one all along. 260-odd astronomers at a convention of more than 2,000 astronomers have no scientific basis for saying otherwise. No matter how important their foible makes them feel.

[Is this post a good troll? I think it is a good troll. I think it is like a storm surge on top of a super tide, that would stir things up, keep the cauldron bubbling. But in a good way.]

Re:And still

[Smauler]

Really, the only categorization issue that I'm adamant about is that Pluto-Charon is called a binary. The Pluto-Charon barycentre is not inside Pluto, therefore Charon is not rotating around Pluto, the two are corotating around a common point of space between them. That's a binary.

That definition works, until you realise that Jupiter's barycentre with the Sun is outside of the Sun. Would you consider Jupiter and the Sun a binary system?

To be honest, I don't, but I don't have any real reason _why_ I don't. We could make some arbitrary percentage to define something as a binary, but that's nowhere near as neat as the barycentre not being inside the main body.

Also, if you define binaries as the barycentre being outside of the main body, you're arbitrarily discriminating against small dense suns and planets compared to large diffuse suns and planets. For example, just about any planet orbiting a white dwarf will have a barycentre outside of the white dwarf, whereas just about any planet orbiting a red giant will have a barycentre inside the red giant.

Re:And still

[AK Marc]

No. You are using your definition of "planet", then calling it stupid. I'll agree with you there. Your definition of planet is stupid.

Also, if you are too dumb to think of a single definition of "planet" that includes the traditional 9 planets, then you are too dumb to bother to argue with, there's nothing I could say that would matter. Your tiny, petty little mind is made up and closed, and has no more room for discussions to sway it.

I said "the rules are arbitrary" and you took that as something I didn't say. Obviously you have trouble understanding, anyway. Another reason logic and reason won't work on you.

Re:And still

[david_thornley]

The rule of "dominates its orbit" or whatever it is isn't arbitrary in the sense that "big enough" is. Earth has cleared its orbit. Anything that stays around Earth's orbit is constrained by Earth's position. The same is true of Mercury, Venus, Mars, Jupiter, Saturn, Uranus, and Neptune. It is not true of Pluto or Ceres.

Re:And still

[AK Marc]

The rule of "dominates its orbit" or whatever it is isn't arbitrary in the sense that "big enough" is.

Yes, it is.

Earth has cleared its orbit. Anything that stays around Earth's orbit is constrained by Earth's position.

There are about 10,000 known objects in "Earth's orbit" The orbit isn't cleared. I've seen numbers for similar numbers for the other planets. The arbitrary rule in that is that the sum of same-orbit objects should be under 0.01% of the mass of the clearing object, or something along those lines. Again, we have to put some arbitrary line in there, because no absolute ever works.

Every rule is arbitrary, so it comes down to which arbitrary do you prefer?

Re:And still

[david_thornley]

The result would be the exact same with a wide range of masses. It's clear that there's no objects of significant size around Earth's orbit that aren't Earth or orbiting around Earth This measure is far less sensitive to values than required planetary mass.

Re:And still

[RockDoctor]

Really, the only categorization issue that I'm adamant about is that Pluto-Charon is called a binary.

What does describing Pluto and Charon as a binary bring to the conversation? Does it allow you to describe the properties of the entire system without having to individually describe the component parts?

Re:And still

[RockDoctor]

That way, maybe we will finally get to name its companion "Goofy", rather than that dumbass Charon moniker.

I'm going to assume that you don't know the origin of the name of Charon. It's quite a sophisticated semi-private joke between the rules of astronomical nomenclature and classical literature. "Goofy", on the other hand is just some stupid cartoon joke.

Re:And still

[RockDoctor]

It has the orbit of a comet and it may vent particles like a comet.

Citation required.

I do make a reasonable effort to keep up to date with the scientific literature, and i've not heard that claim.

Are you perhaps thinking of Chiron?

Re:And still

[pjbgravely]

Like I said, we should know for sure soon. This is one idea.

What's the big deal, anyway?

[Anonymous Coward]

Does this guy want to consider a bunch of other Trans-Neptunian objects as planets too? Because if he doesn't, he's probably either letting nostalgia or some other emotional attachment cloud his judgment. I don't mind having a half-dozen more "planets", but I'm sure my kids might get annoyed at having to remember all of their names.

Re:What's the big deal, anyway?

[confused one]

That's the general idea. You have to add all the objects that meet the criteria. The current criteria does not depend on characteristics of the object itself; the definition includes characteristics of the surrounding objects as well. I tend to agree with the argument that the current definition is wrong, for this reason.

The Kuiper belt and scattered disk are where all the remaining stuff left over from the formation of the solar system ended up. It was pushed out there by the larger planets. Unless the body is very large, for example like Uranus, it's not going to be able to "clear it's orbit" in that region of the solar system. If another large planet did exist out there, it would probably scatter everything in it's orbit, effectively pushing the Kuiper belt and scattered disk further out. Any smaller body, perhaps even an Earth sized body, would be unable to clear it's orbit. So, if the Earth's double was found out there, you would have to call it a "dwarf planet" by the current definition. That doesn't make sense.

Re:What's the big deal, anyway?

[sumdumass]

You have to add all the objects that meet the criteria.

No you do not. you can create an exception into a rule quite easily. I before E except after C. See, a rule with an exception and the earth nor it's inhabitants suffered major catastrophe. And if you look, you will find words that violate those rules too.

Re:What's the big deal, anyway?

[Anonymous Coward]

I before E except after C.

What a weird and foreign rule, with so many exceptions from the exception. A scietifically-minded species such as ours should have been sufficiently intelligent to create a more efficient spelling system than this. Let's just hope that future generations seize the opportunity to get rid of this ancient and inefficient spelling rule.

Re:What's the big deal, anyway?

[confused one]

In science, if you're having to make exceptions to fit the rule to nature, then the rule doesn't make sense.

Re:What's the big deal, anyway?

[khallow]

Exceptions like "this rule only works for one star system"?

Re:What's the big deal, anyway?

[sumdumass]

The rules make sense enough for the most part. There seems to be a couple exceptions to the rules in science that nobody cares about. For instance, Mammals give live birth- except for the platypus and spiny anteater. Eggs need to be fertilized- except in some bee colonies where male bees or drones develop from unfertilized eggs.

There are plenty more and one more will not matter much at all.

Re:What's the big deal, anyway?

[ultranova]

Does this guy want to consider a bunch of other Trans-Neptunian objects as planets too? Because if he doesn't, he's probably either letting nostalgia or some other emotional attachment cloud his judgment.

Or he realizes that the whole concept of a "planet" is just a historical curiosity from ages long past, was invented by people who had no idea what they were describing, and is thus bound to lead to problems in scientific context. Best delegate it to the realm of public relations, where it can serve a useful role to give people a rough idea of what's being talked about without getting mired in details.

So: "A planet is an astronomical object the speaker thinks is best described as a planet."

Re:What's the big deal, anyway?

[painandgreed]

A scietifically-minded species such as ours should have been sufficiently intelligent to create a more efficient spelling system than this. Let's just hope that future generations seize the opportunity to get rid of this ancient and inefficient spelling rule.

Counter point to that feeling is that the language and people using it benefit far more by being able to adopt foreign words than they would be by using standardized spelling.

Better definition of planet

[Hanzie]

As far as I'm concerned, if it's gravitation is enough to pull it into a sphere, it's a planet. Yes, I'm happy counting Luna and a bunch of other satellites. Let's face it, "Believing" has nothing to do with it. We grew up "choosing to label" Pluto as a planet.

How many exoplanets pass the current IAU definition of 'planet'? I bet a bunch don't.

Re:Better definition of planet

[rossdee]

"How many exoplanets pass the current IAU definition of 'planet'? I bet a bunch don't."

What jurisdiction does the IAU have outside this solar system anyway?

If there are inhabitants of those exo-solar systems then they get to decide.

Re:Better definition of planet

[Anonymous Coward]

How many exoplanets pass the current IAU definition of 'planet'? I bet a bunch don't.

I would bet that every single one of them does. Current exoplanet detection techniques are only sensitive to the big ones in close orbits. To detect something as small as Pluto, in a distant orbit in which it might not have cleared its orbital zone of debris (and so not be a planet, by the IAU definition), is well beyond our current capabilities.

Re:Better definition of planet

[Anonymous Coward]

Given how little we know about exoplanetary systems, who knows. I will say that as an astrophysicist studying exoplanets, I have yet to meet a person who primarily studies exoplanets who cares about the definition. I've met planetary scientists (as in people who primarily study planets in the solar system), but to be honest, most people of the people who seem to get all worked up about this are amateurs and people who study Pluto specifically.

Re:Better definition of planet

[QuasiSteve]

As far as I'm concerned, if it's gravitation is enough to pull it into a sphere, it's a planet. Yes, I'm happy counting Luna and a bunch of other satellites

Is the Sun a planet?

We grew up "choosing to label" Pluto as a planet.

At one time people grew up 'choosing to label' Venus as a star. Then we grew up some more and realized we may have been mistaken or at least felt we should have a more granular scale with more accurate definitions.

Re:Better definition of planet

[Beck_Neard]

Holy balls, how many times have we had this conversation? Will you people ever give it a rest?

First of all, the IAU's definition is for technical and scientific discussions/communications. If you want to call Pluto a planet on your blog or whatever, go fucking wild. The IAU neither has the power (nor the desire!) to dictate language for all human beings for all time.

Now about technical language. The purpose of technical language is to provide a common agreed-upon vocabulary that is consistent, precise, and efficient. If you named everything a planet, you'd lose precision. People would inevitable invent a new set of categories for the eight 'big' planets and the other 'smaller' planets. Some people's new terms would conflict with other people's terms. It would be a mess.

On the other hand, if you named the 'big' planets anything other than 'planet', it would lose efficiency. They are the planets that are talked about most often, so it makes sense to give them a short, concise name.

Yes, the IAU's definition of planet WAS DESIGNED explicitly so that the eight 'main' planets would be the ONLY ones in our solar system called planets. There are very good reasons for this and the IAU did its job quite well in this regard.

Re:Better definition of planet

[Black Parrot]

What jurisdiction does the IAU have outside this solar system anyway?

What jurisdiction do they have anywhere?

Re:Better definition of planet

[WaffleMonster]

Holy balls, how many times have we had this conversation? Will you people ever give it a rest?

And queue yourself not giving it a rest.

First of all, the IAU's definition is for technical and scientific discussions/communications.

Scientific labels tend to be intentionally recognizably distinct from popular ones as lack of distinction is an invitation for ambiguity and confusion.

People would inevitable invent a new set of categories for the eight 'big' planets and the other 'smaller' planets. Some people's new terms would conflict with other people's terms. It would be a mess.

Yes this is what you get for "voting" rather than recognizing more work is needed to build consensus to get everyone save outliers onboard. 1/3 disagreeing isn't a consensus.

On the other hand, if you named the 'big' planets anything other than 'planet', it would lose efficiency. They are the planets that are talked about most often, so it makes sense to give them a short, concise name.

This sounds a bit lame as justifications go... lose efficiency? Since when are scientists in the business of conserving syllables? In astronomy especially they seem to be preoccupied with naming things after _all_ the principals who discovered them.

Re:Better definition of planet

[frinsore]

As far as I'm concerned, if it's gravitation is enough to pull it into a sphere, it's a planet. Yes, I'm happy counting Luna and a bunch of other satellites

Then wouldn't our very own moon be a planet and not a moon by that definition?

Most people are ignorant that Earth's moon has a proper name: Luna, or that the term satellites refers to anything that orbits another body. Man-made satellites have recently become the primary definition of satellite but the original definition is still very much valid.

Another interesting fact: Earth's sun's proper name is Sol.

Re:Better definition of planet

[ideonexus]

Up until last Thursday night, I completely agreed with you. I thought that if an object had enough mass to pull itself into a sphere, it should be a planet. I thought the IAU's definition of planet was an offense to reason--well, I still think it is. Requiring an object to have "cleared its orbit" is a silly concept that would mean gas giants larger than Jupiter would be "Dwarf Planets" if they were found in a proto-planetary disc. The name, "Dwarf Planet," is completely stupid and offensive. How is a "Dwarf Planet" not a planet if it has "Planet" in the #$%^ing name???

Then, just this last Thursday night, I attended a lecture by the very engaging, highly-studied Neil deGrasse Tyson. The guy who declassified Pluto as a planet in the Hayden Planetarium exhibits long before the IAU did so officially. He explained to us that Pluto was mostly a dirty ball of ice... like a comet. In fact, if it were in orbit around the Earth, it would have a tail.

That took me aback. If Pluto is just a particularly large Kuiper Belt object--if Pluto is just a large comet that isn't close enough to the Sun to melt, then I must admit that it doesn't make sense to call it a planet.

This is a bit of an iconoclasm for me, so I'm still figuring out my position on the matter, but I'm leaning toward accepting that Pluto is not a planet, but that the IAU is a bunch of numbskulls who need to fix their illogical, nonsensical definition of "Planet" and take the word "Planet" out of their labels for things that aren't planets. This is the kind of political bullcrap that turns kids off to science.

Of course, all this could change when New Horizons reaches Pluto this July.

Re:Better definition of planet

[Deadstick]

Another interesting fact: Earth's sun's proper name is Sol.

You mean it's Jewish?

Re:Better definition of planet

[Anonymous Coward]

How many exoplanets pass the current IAU definition of 'planet'? I bet a bunch don't.

But under the definition you grew up with where Pluto is a planet, there are over 100,000 planets in our solar system alone.

Since you seem to want things how they used to be, first grade school children are expected and demanded to recite ALL the solar systems planets by name from memory.

Can YOU name all 100,000+ planets in our solar system from memory? With Google? At All?

So you basically expect first grade children to do what you can't, all because of "I'm old and I don't like things that are different"
Quite fair.

Re:Better definition of planet

[BarbaraHudson]

A moon is a co-orbiting object with the barycenter of rotation inside the larger object

So the moon will suddenly become a planet in it's own right when it recedes far enough from earth ... - except that then earth has NOT cleared its orbit of major objects within its orbit, so it is no longer a regular planet, and neither is the moon.

Re:Better definition of planet

[BarbaraHudson]

So what would you say if a ball of ice the size of earth were discovered in a normal orbit? Planet? What if it were close enough to the sun to generate an atmosphere, if not a tail. Technically speaking, earth is slowly bleeding atmosphere, which would show up as a tail with sensitive enough instruments.

Re:Better definition of planet

[Your.Master]

Scientific labels tend to be intentionally recognizably distinct from popular ones as lack of distinction is an invitation for ambiguity and confusion.

No, they don't. The only example I can think of for that is IUPAC organic chemical naming conventions, and that's because IUPAC naming conventions define an algorithm for naming an unbounded number of chemicals, even ones never mentioned before, unambiguously.

Here are some short, simple scientific words from the top of my head that are often used differently by the non-scientific community:

force
energy
work
power
theory
weight (very similar to planet, the public often conflates weight and mass which are separated in scientific contexts)
proof
accuracy / precision
chemical
bug
insect
fruit (hence the infamous debates about tomatoes)

Yes this is what you get for "voting" rather than recognizing more work is needed to build consensus to get everyone save outliers onboard. 1/3 disagreeing isn't a consensus.

You've got it backwards. You're saying before you can solve the problem, the problem needs to be solved.

This sounds a bit lame as justifications go... lose efficiency? Since when are scientists in the business of conserving syllables?

Since always. Ever notice how variables names in physics formulas (and pure math formulas) are single-characters, even though that means we have to reach into multiple alphabets? That's punishable by death in most software contexts.

Re:Better definition of planet

[Beck_Neard]

I'm just going to concentrate on your last point as all the rest have been taken care of by Your.Master.

> This sounds a bit lame as justifications go... lose efficiency? Since when are scientists in the business of conserving syllables? In astronomy especially they seem to be preoccupied with naming things after _all_ the principals who discovered them.

It's not just scientists, it's human beings. Language evolves towards better efficiency. That's why the word for 'house' isn't supercalifragilisticexpialidocious, and you use the word 'me' to refer to yourself, not 'pneumonoultramicroscopicsilicovolcanoconiosis' (that's an actual word).

There is such a tight relationship between how often a word is used and how long it is, that you can actually use that as a metric for discriminating natural and non-natural languages: http://en.wikipedia.org/wiki/Z...

Even in science, over time people tend to abbreviate and contract words. In scientific writing, you don't write "The force is 11 Newtons", you write "The force is 11 N", or just "f = 11 N" and most other scientists know what you mean even if you don't explain those symbols.

Re:Better definition of planet

[Beck_Neard]

It's important to define a common vocabulary in science, because the less ambiguity you have in communicating your intent, the better.

If you think this is just something that's done in astronomy, you're incredibly wrong. Mathematicians and physicists and all other types of scientists put in a lot of effort in naming and standardization. It's important.

I agree that it's a *bit* rare to change terms that are already in wide use. But in this case they had to. Their hand was forced because of all the new KBOs that were found.

Re:Better definition of planet

[DMUTPeregrine]

0% of the exoplanets discovered so far pass the IAU's definition of a planet, since that definition specifies that the planet must orbit Sol. Exoplanets are a different category.

Re:Better definition of planet

[Your.Master]

Sol and Luna aren't proper names, they are Latin names. They aren't improper names either, just not better. Their English names are the Sun and the Moon. There's a fine point of grammar in there about inserting the definite article "the" in there, much like in "the Earth" vs. "Earth" vs. "Terra" but never "the Terra".

The Latin names aren't all that obscure either. You might stump people you ambush on the street, but "solar" and "lunar" are well-known terms. I agree that satellite has come to mean man-made satellites in everyday parlance.

Re:Better definition of planet

[khallow]

I agree that it's a *bit* rare to change terms that are already in wide use. But in this case they had to. Their hand was forced because of all the new KBOs that were found.

Because school kids would be forced to memorize a few hundred planets, if measures weren't taken. There was no reason to care that there were a lot of new planets. That's actual science. Now, our "scientific vocabulary" includes "dwarf planets" that aren't "planets". It's just dumb.

Re:Better definition of planet

[Cochonou]

I do not really get this line of reasoning.
I cannot recite the list of mammals or higher primates. My unability to do so has no influence on the definition of these orders.

Re:Better definition of planet

[Gavagai80]

Saving scientists from having to say "non-dwarf planets" every time they want to make it clear they're not talking about the hundreds of KBOs and are rather talking about the type of things commonly called planets in existing literature of centuries, is pretty good motivation.

Re:Better definition of planet

[tsqr]

Earth's moon has a proper name: Luna.

Or Selene, if you prefer Greek mythology to Roman.

Re:Better definition of planet

[AK Marc]

But under the definition you grew up with where Pluto is a planet, there are over 100,000 planets in our solar system alone.

Nope. You must have grown up in a different dimension than me. Pluto was a planet when I grew up, and there were 9 planets. And fewer inconsistencies in the definition than we have today. Though the definition was just as arbitrary as today's.

Re:Better definition of planet

[khallow]

Saving scientists from having to say "non-dwarf planets"

It didn't. They didn't have to say that in the first place.

Re:Better definition of planet

[waveclaw]

Is the Sun a planet?

Yes, the Sun is a planet by the older definition. But the new definition isn't much better*.

The classification of what is and is not a planet changed over time. Now it is tied to some metrics involving orbits and gravity that doesn't even apply well in the Solar System let alone a different Star System.

By the original meaning the Sun and Moon (of Earth) are also planets.

There are 7 objects that visible to the naked eye (say 5.5 magnitude or less at best) which move with respect to the fixed stars (everything above 5.5 magnitude.) Sol, Mercury, Venus, Luna, Mars, Jupiter and Saturn.

The real problem is when you start using telescopes to see things moving in the "firmament" that you cannot see with the naked eye. Then you start seeing things like Vesta, Ceres, Neptune. With a powerful enough scope we can even see Uranus. All of these got called a planets at one time. Some of them are not called planets anymore. Uranus may be full of gas but still gets this top billing.

Planet was once the word for wanderer of the night sky. A nice, simple definition. Now it means something else. Somehow everyone decided once we found out there's a lot of stuff wandering out there, planet became a special status and not just a simple label. In Science and Fiction people travel to or hail from Planet X, not Oblate Spheroid Mass X in orbit around Mass Y where Mass X is much larger than anything else in a similar orbit. The most recent definitions for astronomers appears to just be trying to encode that bias giving a bad definition - complex and counter intuitive.

It's like the term spaceship. If you put a big enough engine on anything and it will fly wherever you want it. So the difference between a space station and a space ship is a question of temporary fitting.

But astronomy is full of definitions that are not well founded (asteroid belt?) Astronomy as a field needs to learn from biology. Cladistics is a big part of biological science. You're going to getting it wrong, even for 100s of years. Naming controversies come with the territory. The International Astronomer's Union is charged with naming things in space so we can all agree on what to call that thing over there. Some of names are going to be arbitrary. Turns out planet is one of those arbitrary names**.

Time is long past to just put up a list of 'these are planets' and everything else is not. Then get used to everyone else, particularly the amateurs, using different lists.

* Over long time scales even rocks are fluids. There is no such thing as a solid on the timescale of atomic stability. There are just temporary crystalline or amorphous structures seeking lower energy states. Humans (or stars) just don't live long enough (yet) to see perfect gravitational stratification of a cold bulk object by quantum tunneling.

** For fun, go look up Asimov's description of the Earth and compare with IAU's definition of a planet. Does Earth qualify?

Re:Better definition of planet

[minogully]

My personal definition is similar to yours, but with a a couple of additions:

1) Gravitation strong enough to pull it into a nearly round shape, but not strong enough to start fusion
2) Does not orbit another planet

This would include Pluto, Ceres, Haumea, Makemake. But it would also include Rouge Panets, which aren't planets according to the official planet definition.

Re: Kinda like systemd / debian

[AvitarX]

I can't tell of this is serious, or satire.

One of the issues discussed doesn't seem to match the others. Primarily, I know best in this area, make me all powerful is exactly the type I would expect to with a minority be pro systems and pro marrying children (because you know who is best for them).

Most excellent Poe style post!

It's never going back to nine planets...

[Anonymous Coward]

By any definition, it's either the 8 we have now, or 10 or 11. That's what started the Pluto mess, we discovered things bigger than Pluto way far out.

Re:It's never going back to nine planets...

[confused one]

it would be much more than 10 or 11. There are 4 other objects that have been recognized by the IAU, Haumaea, Makemake, Eris, and Sedna. There are a number of others which have been observed but have not been recognized yet by IAU. The number could easily be > 20.

It wasn't about Pluto

[Sperbels]

Don't make it sound so sinister. The vote wasn't to demote Pluto. It was a vote to settle on the criteria an astronomical body must meet in order to be a planet. This was necessary because we've found more Pluto like bodies, and chances are we'll find more in the decades to follow.

Re:It wasn't about Pluto

[tompaulco]

So what is wrong with establishing the definition as Criteria 1, Criteria 2, Criteria 3,etc., etc. or objects currently classified as planets? It's not like there aren't other classifications that we ignore if we choose to. We also are in no danger of some intelligent life from another solar system dropping by and saying "What? How is that a planet? It doesn't meet your own criteria!"

Karma

[Livius]

Pluto got what it had coming. It knows what it did.

Re:Karma

[Opportunist]

Damn right, with a silly name like that. Like Hades already said, "what do they wanna call me in Rome? Pluto? I wouldn't even call my dog Pluto!"

Re:Karma

[Opportunist]

You know how to not only kill a joke but bury it and hold the funeral speech...

This is disgustingly insensitive

[Anonymous Coward]

If Pluto self-identifies as a planet then we should respect Pluto's choice.

Re: This is disgustingly insensitive

[Anonymous Coward]

Pluto self identifies as a dog. Lives in a dog house. Wears a dog collar. Goofy lives in a people house. Wears clothes. Goofy is a person.

Re: This is disgustingly insensitive

[Lodlaiden]

well the opposite of God is...

It's not about planets...

[Anonymous Coward]

...it's about whether an AMERICAN-DISCOVERED planet exists.

We have one, the Brits have two. No one else has any...

How about this:

[Anonymous Coward]

Why don't we (rather than going back and forth on what the definition of a planet is, was, or isn't,) just resolve as follows:

Planet Mercury is a planet such that Mercury, (the object orbiting the sun at that location and with that direction or motion,) is a planet of type Mercury. If you prefer, you can call it a Mercury-class planet. Constituents of this class of planet are: Mercury.

Planet Venus is a planet such that Venus, (the object orbiting the sun at that location and with that direction or motion,) is a planet of type Venus. If you prefer, you can call it a Venus-class planet. Constituents of this class of planet are: Venus.

Planet Earth is a planet such that Earth, (the object orbiting the sun at that location and with that direction or motion,) is a planet of type Earth. If you prefer, you can call it an Earth-class planet. Constituents of this class of planet are: Earth.

Planet Mars is a planet such that Mars, (the object orbiting the sun at that location and with that direction or motion,) is a planet of type Mars. If you prefer, you can call it a Mars-class planet. Constituents of this class of planet are: Mars.

Planet Jupiter is a planet such that Jupiter, (the object orbiting the sun at that location and with that direction or motion,) is a planet of type Jupiter. If you prefer, you can call it a Jupiter-class planet. Constituents of this class of planet are: Jupiter.

Planet Saturn is a planet such that Saturn, (the object orbiting the sun at that location and with that direction or motion,) is a planet of type Saturn. If you prefer, you can call it a Saturn-class planet. Constituents of this class of planet are: Saturn.

Planet Uranus is a planet such that Uranus, (the object orbiting the sun at that location and with that direction or motion,) is a planet of type Uranus. If you prefer, you can call it a Uranus-class planet. Constituents of this class of planet are: Uranus.

Planet Neptune is a planet such that Neptune, (the object orbiting the sun at that location and with that direction or motion,) is a planet of type Neptune. If you prefer, you can call it a Neptune-class planet. Constituents of this class of planet are: Neptune.

Planet PLUTO is a planet such that PLUTO, (the object orbiting the sun at that location and with that direction or motion,) is a planet of type PLUTO. If you prefer, you can call it a PLUTO-class planet. Constituents of this class of planet are: PLUTO.

Using this system of classification, we won't have any more arguments about whether or not any given ball of gas, rock, volcanic slag, etc., is or is NOT a planet.

FTFE

Re:How about this:

[camperdave]

Charon is a Pluto-class planet? It is "orbiting the sun at that location and with that direction or motion". What do we do about Eris, Makemake, Houmea, Sedna, Quaoar, Orcus, and 2007-OR-10?

Death Star - Control Limbo!

[burni2]

If that mission is worth a crusade:
I now wish I had a death star I could fly to Pluto and blast it to pieces!

Two reasons Pluto must be a planet!

[Roblimo]

1) Calling the entitled, greedy rich "Neptunecrats" doesn't sound right.
2) Percival Lowell!

Re:Two reasons Pluto must be a planet!

[Tablizer]

Calling the entitled, greedy rich "Neptunecrats" doesn't sound right.

But "Uranuscrats" or "Uranus-craps" is quite fitting.

I consider Pluto a planet...

[jesseck]

http://youtu.be/aq4UGiVEF80 Just because a few scientists say something or vote on it doesn't mean it's that way for all time. I tell my kids there are 9 planets and Pluto is one. I wrong? It doesn't matter.

Re:I consider Pluto a planet...

[Anonymous Coward]

Do you know why Pluto was "demoted"? In order for the designation "planet" to be a usable scientific term, it must mean something consistent. We can't always rely on asking _you_ whether a given planetary body is a planet or not.

Re:I consider Pluto a planet...

[Dutch Gun]

How about educating them on the real history and telling them about your personal disagreement with the new planetary designations?

Personally, as I remember reading about how Pluto was non-spherical and had an overlapping orbit, and thought that it was rather odd for a planet. When I learned about other similar objects that were *not* considered planets, it also seemed fairly odd to me. I never gave it *much* thought of course, and just figured Pluto was to remain a "planet" purely for historical reasons.

When Pluto was reclassified, I was surprised, not because I disagreed with the reclassification, but because I thought the historical precedent and simple "nostalgia factor" would be too difficult to overcome. That it wasn't is actually encouraging to me, in terms of that scientific body, because it demonstrated a willingness to challenge their own assumptions and biases, and to move beyond them when evidenced suggested that they should do so.

Re:I consider Pluto a planet...

[Deadstick]

"How many legs does a dog have if you call its tail a leg? Four. Calling a tail a leg doesn't make it a leg."

--A. Lincoln (provenance uncertain)

Re:I consider Pluto a planet...

[ZombieBraintrust]

Why would you exclude Ceres? The dwarf planet between Mars and Jupiter? It was also once considered a planet. It is round. Telling you kid there is 9 makes no sense. There is either 8 or more than 10+.

Re:I consider Pluto a planet...

[camperdave]

I considered Pluto to be a planet up until about five minutes ago. I came upon this picture showing the major bodies that could also be considered planets. Being unfamiliar with Orcus, I decided to read its Wikipedia entry, and I came across this:

Orcus is a plutino, locked in a 2:3 resonance with Neptune, making two revolutions around the Sun to every three of Neptune's. This is much like Pluto, except that it is constrained to always be in the opposite phase of its orbit from Pluto: Orcus is at aphelion when Pluto is at perihelion and vice versa. Because of this, along with its large moon Vanth that recalls Pluto's large moon Charon, Orcus has been seen as the anti-Pluto.

Orcus and Pluto have "mirror image" orbits, and are both tied to Neptune's orbit. Then it struck me that that makes them like Jupiter's trojan satellites, or the asteroid that is in a horseshoe orbit around Earth.

Pluto just happens to be in a gravitational "sweet spot" with respect to Neptune. Orcus is at another. That gravitational sweet spot also explains why Pluto has five moons, and maybe even rings. Pluto is just a piece of dirty ice that got caught in a gravity divot. Same with its moons. Apparently, all of the other Kuiper belt "planet candidates" are also in gravitational resonance with Neptune.

"Haters"

[Dogtanian]

The efforts of a very small clique of Pluto-haters within the International Astronomical Union (IAU) plutoed Pluto in 2006

Yeah, that's right. They were "Pluto-haters". Not just people who happened to hold a different opinion he doesn't agree with.

That's not to say that you have to agree with their position, nor the way they went about having Pluto stripped of its status. But to ascribe their actions to the fact they personally "hated" Pluto- rather than simply believing that it couldn't justify its status as a planet- is somewhat childish.

I don't know if he meant "haters" in present-day sense (i.e. with its "haters gonna hate" connotations et al), but I've always had contempt for that usage. It's a cheap and easy way to counter anyone you don't agree with, to depersonalise and dismiss them in as people who hate purely because they're "haters". To make it a personal beef and a partisan issue rather than one of simple disagreement on a particular matter- one which would require legitimately addressing what they're actually saying instead of trying to puff yourself up in the cod-macho bullshit "them versus us/me" manner of an adolescent who's either immature enough to see things in that light, or has nothing to say beyond the convenient "haters gonna hate".

Seriously, step away from the gangsta rap and stop acting like a f*****g fourteen-year-old.

Re:"Haters"

[serviscope_minor]

They were "Pluto-haters"

Yep. Haters gonna hate. Pluto gonna er... plut...?

Re:"Haters"

[Dogtanian]

To be fair, the argument against calling Pluto a planet was really political more than scientific--it's hard to argue that there's some nonarbitrary scientific justification for removing Pluto's planet status.

I'm sure those on the other side of the debate would argue that it's just as political and arbitrary to claim that it *is* a planet, beyond pure inertia (i.e. because it had always been called a "planet" until then).

Two wrongs don't make a right

Precisely.

Anyway, they were Pluto-haters, or haters of the idea of smaller planets messing up their tidy worldview.

Now I think you're trying too hard to rationalise the "haters" label. As I said, you don't have to agree with their opinion, nor the way they went about getting the result they wanted.

But that doesn't change the fact that dismissing their opinions and actions purely as "haters" was quite silly.

If the argument had started to become too personal, then this sort of concerted attempt to justify that way of thinking simply makes it worse. As you said, two wrongs don't make a right.

Re:"Haters"

[david_thornley]

Try to make a reasonable definition of "planet" that includes the traditional nine ones, and no more. It's easy to come up with a definition that specifies eight planets, and it's easy to come up with a definition that specifies lots of them. It's hard to come up with something reasonable that includes Pluto and doesn't include, say, Ceres and some Kuiper-belt objects.

Re:Meanwhile, in 1802...

[Rei]

Ceres is also a dwarf planet. An increasingly interesting one at that. Really I find it pretty amazing that space exploration has practically ignored such a large, nearby body with tons of launch windows up to this point.

Mega Net Neutral Pluto

[turkeydance]

ok. i'm confused. /. is not helping.

non-rational scientists

[dltaylor]

Even people in science careers are not immune to significant irrationality (I know, hardly Earth-shattering news).

When my grandmother was young, there were only eight planets, plus a few largish asteroids, then someone discovered another. As our instruments improved, we found many, many more "wanderers". We also learned how how their composition varied, and that there were more-descriptive categories to apply to the various bodies not only in this stellar system, but others.

It is utterly irrational to continue to collect Pluto into the same category as the eight other major rocky/gassy/icy Sol-orbiting bodies (the traditional "planets"), and NOT include the dozens of KBOs, TNOs, etc. that also orbit Sol https://en.wikipedia.org/wiki/Portal:Solar_System.

Of course it's not a planet

[stud9920]

Pluto's Mickey's friend.

Re:Get a life

[avgjoe62]

Who needs to get a life? The guy that studies astronomy and wants to correct what he thinks is an error by some of his peers or they guy that reads a blurb on Slashdot and then makes a snide comment?

Then again, I am taking you to task for said snide comment, so... I think I'll go outside for a walk and see if I can find a life.

It's Easy...

[bswarm]

If it has a moon it should be labeled a planet. Done, end of conversation. But what if a moon has it's own moon, hmmm.

Re:Hey, NASA!

[Opportunist]

Yet still our best telescopes can barely make out its shape.

Re: Kinda like systemd / debian

[serviscope_minor]

Wow, I don't normally read AC posts, but you are right. Most excellent Poe style post indeed!

Re:Not a Quorum

[Chess_the_cat]

That's the most shocking fact from the article. That it was decided by a handful of astronomers. What would the decision have been if everyone had voted? Or at least a majority of attendees?

Re:Scientific names

[Anonymous Coward]

You're an idiot. The word Planet predated the IAU by thousands of years. Do you even know what Planet means ? It meant a wandering star. Yeah star. The ancients categorised stars into 2 classes : those that were fixed on the celestial sphere and those that moved around (and you could see with the naked eye). Comets were not considere planets.

So I guess we have 9 stars in our solar system. Damn that must have slipped my mind.

Analogy

[TMB]

Here's an analogy I gave my students last week...

Imagine you're an alien and you land on Earth in front of a pet store. You go inside and you start meeting dogs. Some are big with a loud deep "WOOF", some are small with a quieter higher "ruff" and there's one little one that goes "meow". Some of them have big floppy ears, some of them have little floppy ears, and that little one has sharp pointed ears with tufts on the end. You think "That little meowing dog with the pointed tufted ears is an unusual dog!"

Then you go onto the rest of the pet store and find a whole bunch more small meowing things with pointed tufted ears, and you say "Oh... I see. That wasn't a funny dog, that was just the first cat I met!"

Pluto was the first Trans-Neptunian Object we met, and so we originally called it by our existing language ("planet"). But once we had a much better lay of the land, it became clear that it was just the first example of a quite different type of object.

[TMB]

Who cares....

[EdwardFurlong]

I mean would a rose by... stop the bickering, nothing is anything except for what it is.

Going my own way

[fyngyrz]

As far as I'm concerned, if it's orbiting a star, and it itself isn't another star, and it's got, or had, enough mass such that it pulled whatever it is made of into a spheroid, it's a planet. If it's orbiting another planet and the center of the orbit is within the other body, it's a moon, spheroid or not. If the center of the orbit is in space, they're both planets. If there isn't enough mass to pull the thing into a spheroid, and it's not orbiting a planet, then it is either an asteroid (primarily rocky) or a comet (primarily gassy/icy.) If it's pulled itself into a spheroid and is floating out away from any star, it's still a planet, but it is a rogue. We can have a moon orbiting another moon and so on, but that doesn't make the first one into a planet.

If an object is manufactured and not meant to navigate to arbitrary destinations under its own power, but only resides in orbit about something or sits in free space, if it can host humans, it is a space station. If it cannot host humans, and it's in orbit, it is a satellite. If it is in free space, it is a platform. If it can travel under its own power to arbitrary destinations, arbitrarily change orbits and so on, it is a spacecraft. Station keeping effectors do not count, and being able to carry humans doesn't make a difference.

If the object is, or ever was, host to a natural fusion reaction due to the usual culprits, it's a star. Live, dead or otherwise.

I could go on for quite a while, but most likely, no one cares anyway. :) The important thing is *I* know what to think when I learn about something "out there." And Pluto? Pluto is definitely a planet.

If someone convinces me that these ideas are inconsistent, I'll do my best to fix 'em so they aren't.

Re:Going my own way

[earthminion]

"As far as I'm concerned, if it's orbiting a star, and it itself isn't another star, and it's got, or had, enough mass such that it pulled whatever it is made of into a spheroid, it's a planet"

So what about a Rogue planet. :)

Re:Going my own way

[Smauler]

As far as I'm concerned, if it's orbiting a star, and it itself isn't another star, and it's got, or had, enough mass such that it pulled whatever it is made of into a spheroid, it's a planet.

So how many planets orbit the Sun, according to that definition?

Re:Going my own way

[eric_harris_76]

Your post makes an enormous amount of sense. I'm surprised you haven't been attacked.

What about protostars, or protostars in the making? I assume (perhaps incorrectly) that a coalescing glob of gas may clearly be on a path that leads to fusion but isn't yet doing fusion yet.

Could one be visibly (or rather, detectably) radiating light or IR or whatever, from infalling mass alone?

To return to the topic: would any of these be considered stars, by your definition, or something(s) else?

Re:Going my own way

[Frobnicator]

As far as I'm concerned, ... no one cares anyway. :) The important thing is *I* know what to think when I learn about something "out there." And Pluto? Pluto is definitely a planet. If someone convinces me that these ideas are inconsistent, I'll do my best to fix 'em so they aren't.

We see articles about how few people are scientifically literate, and so many on Slashdot decry "We are geeks, we understand science!"

Appearently, nope!

Scientists, the astronomers who spend their days and nights studying the stars and planets, people who are intimately familiar with the definitions, and people whose life work and career funding depend on them, came up with a set of definitions.

The definitions draw a line somewhere, and you can argue they are as arbitrary as a meter and a kilogram, or a foot and a pound. You can spend your days arguing that the measuring stick is the wrong size, or spend your days convincing the rest of the world that they need a different measuring stick, or otherwise be a nay-sayer and contradict the consensus of the scientists.

But to decry that because you learned something one way, therefore that convinces you forever, that's just plain stupid.

Re:Going my own way

[IHateEverybody]

That's the thing. This definition includes Pluto but it also includes Ceres, the largest asteroid. It also includes Eris (of course since Eris is even larger than Pluto, any definition of a planet that includes Pluto must also include Eris). And it includes at least six to eight Kuiper Belt objects like Quaoar (the scrabble world whose name I've almost certainly misspelled). Plus a couple of scattered disk objects like Sedna which seem to just be out there in weir, random-looking orbits would also have to be included.

And this list would only grow as better telescopes and better survey techniques are developed. Here I think is the real reason that Pluto was demoted. Because it's easier to take it off of the list of planets than to include dozens of small, icy worlds.

Re:Going my own way

[fyngyrz]

Covered it. Read my post again.

Re:Going my own way

[fyngyrz]

I don't know -- I think it's about 13 right now? Could be more or less.

Why?

Just to be explicit, I wasn't complaining about the number nine. Just the very weird and arbitrary demotion of pluto from planetary status. Which I do not go along with.

I like a nice, sane, consistent definition. :)

Re:Going my own way

[fyngyrz]

I don't see why, when another planet is discovered, we can't admit it.

So... "the problem"... doesn't strike me as a problem.

Re:Going my own way

[fyngyrz]

A protostar, given it's in a seriously pre-fusion state, will (as far as I know) be large enough to have quite decisively pulled itself into a spheroid. If it is orbiting another star, I'd say that at that point, it is a planet and a protostar.

As I see it, protostars seem to refer to a class of planet, just as do gas giants, balls of frozen gasses, molten worlds, rocky, airless worlds, and earthlike worlds. That namespace is a very rich field to till, I think.

Once it lights off, I see it as a sibling (binary, trinary, etc.) by virtue of being stars in thrall to one another's gravity. The star with the greater mass I'd call the primary, the next most mass the secondary, etc.

If it is just sitting out in space by itself, I'd designate it a (rogue) planet and a protostar.

Sure, planets can radiate all kinds of things, for all kinds of reasons. Aurorae, ionizing radiation, IR, UV (some high energy electrical storms do this here), atmosphere, monkeys in tin cans... :) ok, that's pushing the indirection a little hard, but... lol

At this point, I'd say that anything that had lit its fusion lamp gets the designator, quite possibly qualified, of "star." There are various kinds of post-fusion states; neutron stars, black holes, perhaps even just dead cinders and fragments, and of course gassy / radiative remnants resulting from their destruction. Probably lots of other things too. The world, Horatio... etc.

That's all just my own outlook though.

Re:Going my own way

[ilparatzo]

There is a point where broadening your definition of something makes the definition next to worthless. If there are a couple dozen planets in the solar system, many of which are just big asteroids that act like asteroids and not planets, then you're having to create a new definition for "real" planets because of all the garbage collected in the broader definition.

The word "Planet" should mean something apart from a round object that orbits a star. It should mean something that makes you understand basically what it is and what it isn't and the ramifications of it's existence. I should be able to look at one planet, and a second planet and go "yeah, those are planets". Since I was a kid, Pluto has always been the "weird" planet, the one that didn't operate like the others. So when it lost it's "planet" status, it seemed natural to me on some level.

Who cares if it's called a "dwarf planet"? Who does this harm other than the discoverer of the planet, or those that are obsessed with the idea that it MUST be a planet? Whether it's called a planet, a dwarf planet or a bagoglifunkle, it's still a large object in the Kuiper belt that should be known of and studied. Most people didn't even know are Ceres, but it's got a mission going to it, even though it was never called a "planet".

Seems like a lot of wasted energy on both sides of the argument.

Stop right there!

[fyngyrz]

fruit (hence the infamous debates about tomatoes)

Tomatoes are axiomatic components of both pizza sauce and spaghetti sauce. You fuck with tomatoes, you are fucking with the fundamental forces that hold the universe together. Back the fuck off before you do something we'll all regret.

Lost grant funding?

[Roger W Moore]

Why does the concept of another category, dwarfs, enrage people?

I don't think it does but for the definition to work it will have to have some sort of sensible criteria to separate them from asteroids. However clearly the notion that Pluto is not a planet really upsets a lot of people which is something I find hard to understand. Does it really matter that much how we classify it? Indeed it seems such a silly, unimportant thing to be arguing over again when there is real science to be done that it makes me wonder if the astronomers involved have lost their grant funding and so have nothing better to do with their research time.

Re:Lost grant funding?

[Rei]

I don't think it does but for the definition to work it will have to have some sort of sensible criteria to separate them from asteroids

It does - gravity high enough to deform it into a sphere.

Re:Lost grant funding?

[RockDoctor]

some sort of sensible criteria to separate them from asteroids

It does - gravity high enough to deform it into a sphere.

Making Ceres and Vesta planets.

That's OK, I'm cool with an 11-planet solar system. Given the near certainty of there being other spherical planets in the Kuiper Belt and Oort Cloud, I'm cool with a solar system of a couple of dozen planets.

Nationalism

[jzu]

To put this ruckus in perspective...

The demoting caused a drama in the US mostly because Pluto was the only planet to have been discovered by an American.

Wrong argument

[Grismar]

Whether not Pluto is a planet is simply a matter of checking against the definition. If we, in doing so, find the definition either to be too vague to allow us to classify Pluto, or we find the definition lacking - then we can have a discussion about fixing the definition. And after that, deciding whether Pluto is a planet or not is a cinch. So, it this guy has valid arguments about the clarity or completeness of the "planet" definition, by all means lets have that discussion. Although I also fail to see how redefining a category has any scientific value if it's not done in the context of being able to make statements about said category.

Re:Hey, NASA!

[drinkypoo]

I don't really know or even especially care whether Pluto should be called a planet, but it seems like the resolving power of our optics should not be the defining quantity.

Re: More ageist stupidity

[AvitarX]

Well, if we use "everywhere" is limited to only the US, marriage is 16, not 18. If everywhere means the world, there is no global ban. Though there is a treaty that uses "puberty" as a minimum standard.

I can't find any credible source for a global ban existing for young women in the context you use. Please enlighten me.

I don't see the problem....

[mark-t]

If atoms could still be called atoms, even after it was discovered they aren't indivisible, I see no real reason that Pluto could not still be considered a planet, even though it does not actually meet the criteria for a planet today.

Re: More ageist stupidity

[clovis]

Although what you said was basically true, there is a problem with your position.
The problem is that there is no way to write a law with the intent of preventing abuse of people are too young to be able to form themselves to make reasoned decisions about sex or reproduction other than arbitrarily assigning a numerical age as the borderline.

Consider that there are laws and/or policies against adults of any age having sex with people whom they supervise in a business setting. This is because there is no way of separating choice made through duress frm free choice in those situations.

Pluto versus USA

[OrangeTide]

Pluto's surface area is about 1.6x that of the land area of the United States. (or Canada or China, which are all similar in size). But you couldn't fit Russia or Antarctica onto Pluto. I'm not sure if this is an argument for or against Pluto, but it helped me better grasp the size of Pluto.

The surface area of Ceres is a little less than 1/3rd the land area of the United States. It's truly too tiny to be a planet. But it's my favorite dwarf planet.

Oh, science, is it?

[fyngyrz]

We see articles about how few people are scientifically literate, and so many on Slashdot decry "We are geeks, we understand science!"

Appearently, nope!

Actually, my dear fellow poster, it is you that does not understand science. Science is a method. Information gathered and suppositions constructed are both data. Such data, particularly when the scientific method is applied, may give rise to (hopefully) more accurate metaphor(s) (more data) as to how nature behaves, and that in turn may let us go a little (or a lot) deeper next time around. Science is a very simple, and beautiful, method.

Back to data. Data is subject to naming, among other things, and those names are (a) abstracts selected for the convenience of the various users, (b) significantly arbitrary, (c) quite often of a dual or more diverse nature (and still 100% correct), for instance "daisy" and "bellis perennis" and "flower" and "that thing that makes me sneeze" and (d) often extend into the metaphorical and allegorical realms in order to further-, and/or better-, and/or simply re-define the issue(s) at hand. This most definitely includes one's own personal or sharable naming conventions and specifics.

When something is controversial or simply not static, we will often see the naming structure(s) and/or system(s) undergo permutation, mutation or even outright replacement. Brontosaurus, apatosaurus, brontosaurids, etc. Those are good examples of names that changed for some pretty good reasons (wrong head on the body... the "brontosaur" was an apatosaurus that mistakenly got a camarasaurus head on it, lol. Now "brontosaurids" means, hand-wavingly, "those long-necked ones" and not much else.) These nomenclature mutations are part of the process of integrating the data into our best-approximation of knowledge about the world, which, coming back around to square one, is not "science" either. Science is a method that we "do." Knowledge is not science itself, although it can and should be used in the undertaking of science.

Further, as the users of the data, objects, information vary, often so goes the terminology. Programmer: "Time for za!" Secretary sent to get it: "Can I order a pizza, please?" counter person: "pie, cheese" artisian: "yet another culinary masterpiece!"... they're all correct. It's not a problem. It's normal and natural. It is still normal and natural if someone in a particular household begins to call pizza "magic goo"... and who knows, it could be what everyone calls it some years down the road. I still kind of twitch when someone says "you suck", because when I was a teenager, that was a deadly insult, worthy of an immediate fistfight. Means something quite a bit more casual today, something absolutely unrelated to its original meaning. And so it goes. Naming is by its very nature a malleable domain. As it should be.

The bottom line here is, just because a few astronomers (and it was very few, btw) voted for a particular usage, does not mean we have to, or even should, comply if we don't agree. I'm sorry if that seems too chaotic for you, but that's really the way it is, and likely always will be, too.

But to decry that because you learned something one way, therefore that convinces you forever, that's just plain stupid.

Well, good thing I wasn't doing that then, eh?

Cheers! :)

Re:Density is therefore a necessity

[fyngyrz]

A drop of water can self-form into a sphere by surface tension alone. If that is dropped off in space, it becomes a planet??

Not in my view. That isn't implied by what I said, either. I said mass, and I meant mass. If you dropped your putative drop of water off in space, by the way, by which I mean in a vacuum, I don't think it would be able to hold itself together by any means. I suspect it'd most likely sublimate before you even had a chance to really get into admiring it.

Oh, by the way, our sun orbits the galaxy, does that mean we aren't a planet here on earth because we orbit around something that has its own orbit?

Not to me. Again, I said nothing of the sort, and I implied nothing of the sort.

If not, then why do moons get to be moons when many of them are bigger than the "planet" Pluto, when they orbit around something that has its own orbit around another body?

Moons get to be moons in the context of a solar system; once you step beyond that level of organization, most of us (apparently not you, but that's ok) use different terminology to indicate groupings of stars, gas clouds, supergroupings, and so on.

But hey, don't let me get in the way of your irrational ranting; you've got a good head of steam going there, be a shame to see it peter out too soon.

Taylor Mali's Pizza poem for Pluto

[rlh100]

There is always Taylor Mali's Pizza poem for Pluto:
https://www.youtube.com/watch?...

I is a poem about a planet mnemonic:
My very educated mother just served us nine pizzas
Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto

He also has a great poem about teachers and I love his spell checker poem.

Re:Taylor Mali's Pizza poem for Pluto

[tehcyder]

There is always Taylor Mali's Pizza poem for Pluto: https://www.youtube.com/watch?...

I is a poem about a planet mnemonic: My very educated mother just served us nine pizzas Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto

He also has a great poem about teachers and I love his spell checker poem.

Ah, I never could work out how Richard Of York Gains Battles In Vain was supposed to help you remember the planets.

Re:Hey, NASA!

[Opportunist]

Erh... that was a comeback to a "your mom" joke. Mod it funny, mod it offtopic, but don't try to reply on topic to it. :)

Re: More ageist stupidity

[clovis]

The problem is that there is no way to write a law with the intent of preventing abuse of people [who] are too young to be able to [in?]form themselves to make reasoned decisions about sex or reproduction other than arbitrarily assigning a numerical age as the borderline.

That is demonstrably incorrect. Like any matter of competence, an adequate determination of the actual situation can be ascertained by testing. The relevant issues here would include the various facts of the matter (contraception methods and effectiveness, disease varieties, recognition, and prevention, the technical details of becoming pregnant, etc.); the potential consequences as related to catching and spreading STDs, pregnancy, child-rearing, adoption, abortion, social issues such as reputation, etc., basic statistics on relationship durations and other related matters. Any moderately competent educator could set up an adequate testing regime -- there are no technical barriers to this at all.

What you have is described is what should be the result of a good sex education class. I wish everyone could have that experience. Unfortunately, the social forces you mention later in your reply prevent sex education from being taught properly in many places.

But a test to determine if a person is able to make reasoned decisions about sex and reproduction?
What you have described is, before anything else, a literacy test.
It would be great if we could implement this, but what you have described is eugenics. There is no way to write a law in the USA that even remotely smells of eugenics, and that's a fact.
Hmm, it occurs to me now that what I said is unclear. By "write a law", I mean the entire process from drafting it to getting the legislature to pass it and a governor to sign it.

Also, regarding "And no, agency does not instantly arise like some magic fucking flower when the human body crosses a 16-, 17-, 18-, 19-, 20-, or 21-year old "finish line".

This is a straw man. No one makes the claim as you stated it. We know some people under 18 years are competent to sign contracts, and we know that some people will never be competent.
The idea is that we guess when most people at that age will be competent to make reasoned decisions, as well as the societal benefits to allow and/or harm to prevent for the behavior under consideration, whether driving, signing contracts, drinking, or having consensual sex.

Another problem is that setting a numerical age as the borderline does not prevent abuse of the incompetent, nor does it ensure the individual can make reasoned decisions. All it does is create a legal nightmare for young people and anyone who might be involved with them.

That is why in addition to laws protecting the young from exploitation, there are laws protecting the mentally retarded and insane. Admittedly, this is one area that is a legal nightmare with many contradictory rulings. The problem being that laws preventing exploitation of the mentally handicapped also denies their having sex life in their entire life. I think that courts generally believe each case is unique.

The current state of affairs is toxic, unjustifiable, and guaranteed - known - to cause harm on both sides of the lines drawn. Young people below the line who are competent, and anyone involved with them, are subject to incredibly brutal punishments, de facto extreme compromise of their working, interpersonal, childbearing and residential future(s), gross public shaming, vigilantism and more.

That's why we have the so-called Romeo and Juliet laws that allow sex between people of similar ages.
Unfortunately, many states have not written such laws. This is, as you pointed out, a travesty.

Then you continue with what is basically a string of insults that hides the meaning of whatever you were trying to say.

Slingshot ?

[RockDoctor]

when NASA's New Horizons spacecraft slingshots around the icy rock and sends us back a detailed picture of its composition.

For certain values of "slingshot" that include hardly any deflection at all.