No peace over Pluto

Dennis, Richmond VA — Sat, 14 Jun 2008 00:23:28 GMT

If it's big enough to be round, it's a planet. A planet orbiting a larger planet is also a moon. If the planet has a mean radius less than 1000km, it's a dwarf planet. If it's radius bigger than 10,000 km in diameter, it's a giant planet.

No peace over Pluto

Michael,kent oh — Sat, 14 Jun 2008 02:00:48 GMT

A better definition is to just accept that "planet" is a definition that is past its time. Its like the way they used to name chemicals. No one asks for a bottle of 1,3,5-cyclohexene,they still ask for benzene. A similar solution should be used for planets.

The planets are the nine bodies which have been commonly recognized as planets. Its not so much a scientific description as a common description that everyone uses. Once you do that,you can make a nice sensible classification scheme for everything, including the nine planets. Something that makes sense,and something that we can apply easily to any object we find.

No peace over Pluto

BrianGriffinLovesYou — Sat, 14 Jun 2008 02:06:14 GMT

Real precise, scientists judging the world based on the standards of a 1960s TV show. What is this, Galaxy Quest??

No peace over Pluto

Loren, fullerton, ca — Sat, 14 Jun 2008 02:09:49 GMT

I agree. This "clearing" business is annoying. If it is round, it's a planet. If it's not, it's just a rock. If you feel the need to "raise" the position of larger ones, call them major planets or some such term. How will a definition created to try to fence in a certain group of bodies in our system apply to systems we know little about?

No peace over Pluto

Adam Rurik, Mount Pearl, Canada — Sat, 14 Jun 2008 02:12:16 GMT

The term "dwarf planet" is no different than "jumbo shrimp!" Sheer idiocy! Call 'em Plutoids, Oortoids, Hemorrhoids, whatever you like! But there has to be a CLEAR delineation between objects like Ceres/Chiron/Eris/etc. and PLANETS!

No peace over Pluto

STepper, Malibu, CA — Sat, 14 Jun 2008 02:49:55 GMT

Thanks, Dennis. That does it for me. I just hope we don't find a million marbles out there in the Oort Cloud.

No peace over Pluto

uwe fruendt calexico ca. — Sat, 14 Jun 2008 03:09:13 GMT

i totally agree whit dennis. if it walks like a duck, and so on. wow, it must be a duck

No peace over Pluto

Inayat Lalani Benbrook TX — Sat, 14 Jun 2008 03:11:04 GMT

If Pluto is aplanet, so is our Moon

No peace over Pluto

Roy Fritz, Butte, Mt. — Sat, 14 Jun 2008 03:43:52 GMT

I would like to have the foolish money spent on this debate. Does it circle the sun, has it always been counted as an planet until a couple of years ago. Lets be stupid about it, It has been grandfathered in as a planet and leave it at that. There must be a lawyer involved it in somewhere. I think that they are being a bunch of 3d graders.

No peace over Pluto

Guy, Lombard, IL — Sat, 14 Jun 2008 03:44:43 GMT

They find it offensive to be called dwarf planets, or red dwarf suns or anything of the like. The politically correct thing is to call them little planets, etc.

No peace over Pluto

Fred Springer — Sat, 14 Jun 2008 03:46:25 GMT

Planets were defined by our ancient astronomers. Why not leave the term "planet" to describe only the bodies orbiting our star as we are familiar with, and use a different term for other objects in other solar systems and galaxies.

There could be star orbiting bodies called storbiters, and storbiter orbiters called substorbiters. There is no reason that every object in the universe needs to referenced to what is found in our solar system.

No peace over Pluto

John Martinsburg, WV. — Sat, 14 Jun 2008 03:49:25 GMT

A "Scientist" is an entity that orbits a central idea & clears its area of all facts & figures. An entity that orbits a "scientist" is a "specialist". An entity that has not cleared its area of facts & figures is a "research student". Seems logical to me.

No peace over Pluto

Tom, W. Berlin NJ — Sat, 14 Jun 2008 04:17:55 GMT

I completely agree. If it's round and orbits the sun, that's a planet. To classify things scientifically, you generally need the most basic descriptions. (Does it have a spine? Wow, it a vertabrate!!) I loved Alan's Star Trek explaination. Sums it up perfectly. I don't want to fill in a checklist before deciding if what I'm looking at is a planet or not.

No peace over Pluto

James Saicheck, Banning, CA — Sat, 14 Jun 2008 06:43:26 GMT

If it looks like a duck, walks like a duck, quacks like a duck then it must be a chicken! Well, that's essentially what the IAU saying about planet classifications. What if Jupiter were 10x larger, then it would blur the distinction between a planet and a star. If one uses the Earth as a basis for comparison (which is reasonable), then I hardly think Saturn and Jupiter would qualify. The cosmos is replete with blurred distinctions. Whether it quacks or clucks, it's still a bird! If it's round and not too hot, it's a planet!

No peace over Pluto

steve ballmer, redmond, WA — Sat, 14 Jun 2008 09:45:11 GMT

You guys are funny! I wonder how you would define a ham sandwich?

No peace over Pluto

Rob, Arvada, CO — Sat, 14 Jun 2008 10:51:14 GMT

Under your definition, Tom, then Ceres, Eris, and Sedna would also be planets? They are round and they orbit the sun. It doesn't work. We should just go back to the 1930 model and leave it like it was before we started messing with the definition.

No peace over Pluto

Tony Johansen — Sat, 14 Jun 2008 12:02:00 GMT

Mr. Springer,
You seem not to have read any substantial history regarding the ancient definition of a planet, because it is very different to a rocky round body orbiting the sun. The ancients believed planets were gods, who entered and moved around the sky according to a divine plan. Later on the definition was changed to a type of star that orbited the earth in a different sphere to the other planets. In this definition the sun and moon were both classified as planets.

The definition changed to match your understanding of the "ancients" definition only since the Renaissance with the invention of the telescope which first revealed the round nature of planets which was distinctly different to stars. Even after it was realized that the planets orbited the sun and that the earth was actually a planet too the definition of a planet changed according to the knowledge of the day. In the mid 19th century, for example, in order to exclude the asteroids which had from the time of their discovery been regarded as planets.

It is both historically consistent (and logical in the light of new knowledge) to update the definition of a planet. In fact it has become necessary as we discover a large variety of new objects orbiting other stars and new objects orbiting our own. The definition arrived at 3 years ago has too many inconsistencies to have any long term currency. About the only thing it satisfies is the apparent need by otherwise rational people to have the definition roughly fit the one they grew up with and became emotionally attached to.

Eris may well be a plutoid, but it is also likely to be regarded as a planet in the long run. Not only that time is likely to show that planets of the dwarf planet type may well be the most common in any star system, and therefore from an objective point of view the norm amongst planets.

No peace over Pluto

Tom Y., NE, IL — Sat, 14 Jun 2008 12:35:47 GMT

I completely agree too! "If it's round and orbits the sun, that's a planet." However, if you do not apply the "size" rule then some comets would be considered planets, no?

No peace over Pluto

Jimdotz — Sat, 14 Jun 2008 14:08:00 GMT

My children, ages 8 and 11, have learned more about Planetary Science from Pluto's demotion than anything else, and they were fascinated and thrilled with the naming of the Plutoids.

The Star Trek rant above is ridiculous. If it takes time for a regional survey to properly categorize a newly discovered body, so be it.

If you show me a new single-cell organism, must I be able to categorize instantaneously by sight? Wouldn't putting a little effort into it be appropriate?

No peace over Pluto

Jeff Hitchcock, Olathe, Kansas — Sat, 14 Jun 2008 16:41:58 GMT

I was shocked after hearing that "Pluto" was no longer a "planet." I petition a "world vote" of scientist and non-scientists. I would trust that this planet can define other planets(at least in our solar system.) The "Meteoritical Society" votes on "what is" and "what isn't" a meteorite. Is there a connection? I smell something here folks!!!

No peace over Pluto

JC, Fairbanks, AK — Sat, 14 Jun 2008 16:55:58 GMT

Popular opinion on this subject is totally irrelevant. People may well, in fact probably will, continue to call the 9 historical planets "the planets". In deed, I do myself in casual conversation. But the scientific community needs to have a much better definition for the term than it does now, and it makes not one bit difference what opinions pop up in the general public, a new definition for the word "planet" *IS* going to be adopted (if only for use in scientific circles).

Using simply "large enough to form a sphere" is ridiculous. If we used that there would be zero planets; NONE of them are spheres, and this is NOT simply being nitpicky! Some very important effects occur precisely *because* planets are not spheres! If one 'rounds off' this definition to, say, "approximately spherical", then all of sudden we have *dozens* of planets, including all the larger moons.
This whole business came about because Pluto has been recognized now as just one of manymany Kuiper Belt objects. It has the same composition, similar size and shape, and same kind of orbit as KBOs. Therefore, any definition of "planet" based on PHYSICAL characteristics (as opposed to emotional sentimentality) IS GOING TO either exclude Pluto,or include thousands of new planets. Period. And no amount of commenting is going to change that.

That having been said, I think the IAU definition is kind of silly, and doubt if it will last long. It will either get thrown out, or it will simply become irrelevant through lack of use. If the 2nd one happens, the IAU itself will lose alot of credibility in science circles. And either way, they have covered there own faces with egg. But whatever eventually comes out the other end, I'm positive that for science's purposes Pluto is going to stay 'not a planet'; in fact, in practice, it already had been well before this surreal controversy even erupted . . . . .

No peace over Pluto

J.Bradley Charleston,WV — Sat, 14 Jun 2008 17:15:27 GMT

Why can't we just have classes of planet - like they have on Star Trek. Each class would have a certain size range. At the lower end of the scale, below a certain point, bodies could be deemed "planetoids" and then below that they'd be asteroids. A small planet could be called a "planet" even though it classifies in the planetoid range. This would contrast with a "moon". A "moon" is simply an object that orbits a planet or planetoid (Although I'm sure most planetoids don't have the gravity for one.). A "moon" would be defined by it's ORBIT - or that it orbits something, not by it's size. Just because something is the size of a moon, doesn't mean it's considered a moon or another diminutive object. Yes, it's possible that even a COMET could be cosidered a planetoid. A comet has a longer orbit though, and then there's all that gas that appears around them - which makes it hard to LAND on them. Which brings attention to WHY we're classifying these things. So process geeks can stroke their compulsive left brains or so we can actually go out there and DO things. If it's a PLANET - of some type or class - you know you can LAND on it.

No peace over Pluto

JC, Fairbanks, AK — Sat, 14 Jun 2008 17:25:21 GMT

...And for those who may have got their feathers all in a ruffle about the simple fact that their opinions on the technical definition of "planet" don't count, it might be worth considering that there are literally thousands of words whose popular meanings are much different than their scientific ones. In fact the very term "science" means very different things to scientists, vs. non-scientists. To a scientist it means the use of a defined, codified method of investigating the physical universe. To people outside of science, it has almost as many meanings as people one asks (but often involving lab coats and eccentric hair-dos).

The point is that it is not necessary for the popular definition of "Planet" to be exactly the same as the technical one (though it would probably be better if they were).

No peace over Pluto

Steve Rice, Augusta, ME — Sat, 14 Jun 2008 18:35:19 GMT

Sure Kirk and Spock may be able to identify a planet or comet just by looking at it. But at first glance Han Solo misclassified a giant space station as a moon. And later, that space station was reclassified as a Star(of Death). Point being that definitions are constantly changeing and as we learn more about planetary science the definition of a planet is bound to change as well.

No peace over Pluto

Nicole A, Washington, DC — Sat, 14 Jun 2008 18:46:41 GMT

There's another point to this argument that seems to have been widely missed. Much to the shame of all present at the IAU vote, politics came heavily into play and outweighed even science. Pluto was the only planet discovered by an American, and there is a certain amount of prestige associated with discovering "planets", be them in our own solar system or not. Those sullying the waters in these debates are looking out for their own interests in exoplanet discoveries- if a definition is wide enough to apply liberally, they can then discover "planets" around other stars and not just rocks.
Shameful as it is, and as much as the scientific process should not work in this way, this was a factor in play that has not been addressed yet.

No peace over Pluto

Douglas Kitchen, Fullerton, CA — Sat, 14 Jun 2008 18:51:45 GMT

People, it's really all very simple. If it's a body that orbits a sun then it is a PLANET! If the body has other bodies orbiting it, then they are MOONS! Did anyone pay any attention in school when they were growing up? I find it absolutely absurd that we are even having this discussion. What is really going on here is a bunch of college educated brats are having the age old childish squable of "I'm smarter than you are!" and they're using this planet naming excercise to do it. The new generation is thumbing there nose at the old generation. Planets have been Planets and Moons have been Moons for how long now? And all of a sudden, oh no that does not work anymore? Please, give me a break! There are more important things going on in the Universe (Or is that term now obsolite as well?).

No peace over Pluto

Len, Raleigh, NC — Sat, 14 Jun 2008 19:10:55 GMT

Call 'em all planets and put class tags (P0, P1, P2, etc.) on them. E.g., Small, hot, rock like Mercury = P1, Earth size rock = P2, Gas giant = P3, Small, cold, rock/ice like Pluto = P4, etc.

That's what they do with stars and galaxies, why not planets?

No peace over Pluto

Steve Hollasch, Redmond Washington — Sat, 14 Jun 2008 20:33:50 GMT

"Round and orbits the sun" is a bit too simplistic. That definition would include our moon as a planet. "But wait," you say, "the moon orbits the *Earth*". If that's true, you could just as easily say that the Earth orbits the moon: the Earth and moon both rotate around a point 4,600km from the center of the Earth. So then you could define what it means to orbit: "anytime bodies A and B revolve around each other, then A is considered to orbit B if the center of mass of the pair lies within the body of B." Ok, great, the center of the Earth-moon pair lies 13.4% below the Earth's surface. What happens when two bodies revolve around each other, while revolving around a star, and the center of rotation of both lies between them? Which is the moon and which is the planet? What if they're both the same size?

This brings us back to the quandary that location should not affect object classification. If the moon were far enough away that it still paired with the Earth, but brought the center of rotation outside the Earth's radius, then what? They both suddenly become mutually orbiting planets? If you move the moon to its own orbit, does it become a planet? If so you need to accept that you can't classify a planet until you've classified all objects around it, leading back to the initial quandry.

The fact that nobody has yet to come up with a unanimously accepted definition would indicate that this issue is not as trivially easy as some here seem to believe.

No peace over Pluto

Ray, Chewelah,Washington — Sat, 14 Jun 2008 20:36:59 GMT

Is it really worth all the time and money spent arguing this question it's a planet or a star, as long as it doesn't fall from the sky let it be.

No peace over Pluto

John, OKC — Sat, 14 Jun 2008 21:13:28 GMT

Why not just call a planet any body with an appreciable atmosphere? Too simple?

No peace over Pluto

Cathy Northway Champaign,IL> — Sat, 14 Jun 2008 22:02:47 GMT

Hey I know change is gonna happen no matter what but just what is so important that all of a sudden somebody says: oops! we goofed( how many years later?) Pluto isn't a real planet so lets just change it's status and forget about it .

No peace over Pluto

G. Siu, Tallahassee, Florida — Sat, 14 Jun 2008 22:09:20 GMT

This is about as pointless as reclassifying Australia as an island rather than a continent. At what size does an island end and a continent begin? Same thing for space bodies. WHat size or orbit must it have to be a planet? Pluto should be considered a planet even if it isn't just because it has gotten away this long being called a planet.

No peace over Pluto

Lloyd S. Gordon,Montego Bay, Jamaica — Sun, 15 Jun 2008 00:23:02 GMT

Science seeks to communicate information in a precise codified way which blocks ambiguity and the possibilities for misinterpretation as far as possible or foreseeable.The traditional use of the term planet did no allow for the relatively recent discoveries concerning Pluto, but it is fair to say that the term planet in most minds suggest a earth type of body orbiting a star a susceptible of being landed on or walked on, so why don't we stick to the traditional definition since it does not confuse us a provides a fairly clear picture of what we are refering to?

No peace over Pluto

Stephanie, New York — Sun, 15 Jun 2008 00:27:40 GMT

What will be will be, we dont need to poke around the world.. it was made for a reason.. if pluto isnt a planet anymore then thats it. We need to use the money for more important things.

No peace over Pluto

menso guk — Sun, 15 Jun 2008 01:07:15 GMT

maybe the scientific community ran out of things to ponder. This maybe just a ploy to keep their tenure.
smiles.

No peace over Pluto

Larry Ortega, Norman OK — Sun, 15 Jun 2008 01:12:23 GMT

I rather liked the classification of "Kuiper belt object"

No peace over Pluto

Diane, Thunder Bay, Canada — Sun, 15 Jun 2008 02:53:36 GMT

Okay, a body that has enough mass to be round is a planet. if a body orbits that planet, it's a moon. simple stuff here. a body that is not round but still orbits a star is either a comet, an asteroid or a meteroid. (differences im not in the mood to explain) besides, Pluto looses mass everytime it goes near the sun so it used to be a lot larger (no one takes that into consideration) Besides, why waste so much time and money on this? Let Pluto be. It's a planet in my books. I don't care if anyone corrects me when I say there are 9 planets. Pluto is a planet so stop fighting over it.

No peace over Pluto

Des Emery, St. Thomas, ON, Canada — Sun, 15 Jun 2008 04:54:47 GMT

Hey, Shakespeare said it long ago - What's in a name? That which we call a rose, by any other name would smell as sweet. And more recently Gertrude Stein opined that a rose is a rose is a rose.

So the language of discovery is important. But science is neither a colloquy of nodding heads nor an singular pronouncement. Identification of any object may ultimately involve more parameters than mere convenience dictates.

No peace over Pluto

P. Opofla, Christiana, Delaware — Sun, 15 Jun 2008 07:36:56 GMT

This whole controversy has nothing to do with science. Don't be duped by their ridicules and spurious arguments. This is a very blatant nationalistic attempt by some European based members to remove all American identified "Planets" from the text books. To them the situation had become critical with the discovery of "Eris" and the community's need to revise the definition either to included all the recently observed round TNO as planets (mostly by Americans) or permanently exclude them (and all future discoveries) from the list, thereby enshrining Euro-centric dominance of early planetary observations.

I hope we can overcome this petty jealousy and revel in the beauty of scientific research and get back to teaching our children there are still wonders in the universe waiting for them to discover.

No peace over Pluto

Jacky, Toronto, ON — Sun, 15 Jun 2008 08:02:48 GMT

Really want the general public to know this: Stern is the very same person who gave an definition on "cleared the neighbourhood of its own orbital zone" in his own paper (with Harold F. Levison) "Regarding the criteria for planethood and proposed planetary classification schemes" in 2000. He is the person who give us "eight planet", even thought he eats his own words now.

In his own definition, all eight planet cleared its own orbit. Pluto, Ceres or Eris are at least 50000 times weaker in clearning its own orbit (measured by the "Stern-Levinson parameter " on the other hand. Earth, by Stern's own definition, is a planet, while Pluto is not.

As you can see in the interview, Stern fooled the public by using an easy to understand but scitificaly incorrect example: Earth did not clear its own orbit - pretty much the same way as if I say gravity does not exist if I can throw apples upward. Alan Boyle either play along with him, or he is being fooled too.

No peace over Pluto

Tim Rommes, Washington, UT — Sun, 15 Jun 2008 08:57:32 GMT

What about the whole moon issue? Should moons qualify as planets if they would qualify as planets if they weren't moons? Wow, tired. Are moons just a special class of planets? If a planet has a moon it hasn't cleared it's orbit, is that planet a planet? If a huge space rock came through and threw out Mercury so that it landed in orbit around Saturn would it, without any physical change, cease to be a planet and be just a moon? What happens if planetary orbits cross, such as elongated elipses with different major axes?

No peace over Pluto

Tony Johansen — Sun, 15 Jun 2008 10:54:21 GMT

The International Astromical Union has made its ruling. Fine, let it do so and move on. The point being that this is an ASTRONOMICAL union - astro means stars - this is the body of collective investigators into shiny points of light in the distance observed through various telescopic types of instruments.

Alan Stern is a PLANETARY scientist. This is a very different thing. Rather than just observe from a distances, Stern is actually going there via the space craft he is in charge of. If his need is for a certain kind of framework to work within, then his practical needs outweigh the emotional or theoretical needs of others less directly involved in planetary exploration.

Dare I say that the political maneuvering of the IAU to get the preferred definition of the old guard in place smacks more of an attempt to exert power over those such as Alan Stern who are directly involved in planetary research but not part of the IAU. I think a crossroads has been reached where those directly involved in the practical exploration of these distant objects assert their views via the formation of an International Planetary Union.

While astronomers and planetary scientists directly feed into each others disciplines, each needs to recognize that they also have a different focus as they look at similar objects. This is no different to the process during the last 200 years when natural scientists who investigated all natural phenomenon specialized into distinct biologists, geologists, astronomers etc. As knowledge and on the ground experience grows in any subject, specialization is logical.

Just a hundred years ago it was enough for astronomy to include just astronomers. Now astronomers are finding their traditional position usurped by physicists and planetary scientists. This is a natural outcome of a long investigative process. It is not a bad thing.

As the exploration of the planets of this solar system and the others being increasingly found gathers momentum I find the opinions of those going there (like Alan Stern) far more relevant to the subject than a body more concerned with stars, galaxies, big bang's, inflation, strings, and other exotica.

No peace over Pluto

Shawn, Seattle, Washington — Sun, 15 Jun 2008 16:57:47 GMT

Personally, I don't like the reclassification of Pluto. Expansion of knowledge should not void previously well-established knowledge as long as those previously well-established knowledge is good.

In this case, the definition is such a basic concept that even small children learn and care about. It need not try to be the scientific definition that planetary scientists would want to use. I wouldn't mind at all that planetary scientists create 10 more planetary classifications (such as "Orbitally dominating planets" :-)) as long as I don't need to use them to appreciate our solar system.

I don't know what children think about demoting Pluto. Can they really appreciate that science is really such wonderful discipline that requires such rigor? Or they will just have more doubt about what we teach them? Might they be thinking "maybe our Moon is really not a moon?"

Naming is indeed very important to scientists because good names should embody a set of characteristics of the objects. But in this case, as the article explains, the renaming doesn't even help from that perspective.

Now, think about promoting Pluto back to be a planet again? Wow, what confusion will that create? I just wonder how this could have happened?

No peace over Pluto

Omega Supreme aka the SuperCracker — Sun, 15 Jun 2008 17:34:33 GMT

Lets make it easy if it circles a sun its a planet if it orbit around anything other then a sun its a moon. then break add subclassifications based on that. thats how i explained it to my 5 year old and he got.

No peace over Pluto

Scott, Normal IL — Sun, 15 Jun 2008 19:31:50 GMT

John I'm no science buff or anything really, but I remember hearing that mercury doesn't have an atmosphere since its so close to the sun, so the definition of "a planet any body with an appreciable atmosphere" would dismiss mercury if I'm remembering correctly

No peace over Pluto

Steven Douglas, Wuxi, China — Sun, 15 Jun 2008 22:14:19 GMT

Before arguing the merits, look at the playing field, and follow the influences. This is an intensely political process (as is all of science to varying degrees, like it or not).

Just as the 'nine traditional planets' gained acceptance through common usage, so can the IAU gain more acceptance, and therefore gravity, by its own political accretion, as the more of its own definitions become common usage.

If textbooks, scientific papers, etc., follow suit with the IAU's definitions and terms, then it can safely be said that the IAU, has, to a degree, increased its own gravity, and swallowed up a controlling part of planetary science, and ultimately, the scientists themselves.

The political reality in this case, is that in the process of defining a planet versus a plutoid, the IAU has also, metaphorically speaking, defined itself as the planet, with the planetary science/scientists that are not on board in this case, as the plutoids.

Having clearing everything from its own orbit, the IAU can conceivably become the only rightful body that can be considered, metaphorically speaking, a 'real planet'.

No peace over Pluto

Tim Rommes, Washington, UT — Sun, 15 Jun 2008 23:00:16 GMT

Omega Supreme,

That just made comets and asteroids planets. Simple, but perhaps overly so. Sufficient gravity to approximate roundness seems important. Sweeping it's orbit maybe not so much. The distinction of moons is the greatest point of contention. Should they still be classified as planets, just special case planets. It seems to me that composition will be a greater distinction than whether its primary orbit is solar or planetary. This is just a question of what gravity well a planet got caught in, not a question of what it is only where it's at.

No peace over Pluto

pat — Sun, 15 Jun 2008 23:43:31 GMT

A type of double jepardy, is it not. For as long as I can remember it was and is a planet. schools, gov't, law firms... it did not commit a feloney. they have no right to take its classification away. they waited beyond the 7 years.

No peace over Pluto

Gordon Freeman, Black Mesa, Arizona — Sun, 15 Jun 2008 23:43:31 GMT

It's rather disturbing to read the comments on here. From those who think a "planet" is anything that orbits the sun and is round (which would mean there are thousands of planets in our solar system), to those who believe it's a waste of time trying to understand the world/universe around us (was it a waste of time for Christopher Columbus to traverse the Atlantic into an unknown/unexplored area of the world?), to the one who believes that a 'planetary scientist' is someone who flies to other planets in their spaceship (we do not live in Star Trek, Star Wars, or any other sci-fi movie/tv show).

Scientists need precise definitions. Because of the gray area between asteroids and planets, we need to set an arbitrary limit. The following would be a good definition:

A 'planet' is any object with a radius of more than 1000km, that is not massive enough to sustain nuclear fusion, and that has never previously been a star.

The "never previously been a star" is important because stars that have died no longer sustain nuclear fusion. After all, we can't classify brown dwarf stars as planets. Additionally, limiting 'planet' to something that orbits a star would probably be insufficient when we discover rougue planets that have been thrown away from their parent star.

No peace over Pluto

Troy, Auckland, New Zealand — Mon, 16 Jun 2008 00:40:00 GMT

Why haven’t we devised a more scientific classification system based on size, density, and atmospheric conditions? We are really talking about a planet's capability to support life in any form. So if the object orbits a star and is big enough to support a atmosphere of heavy gas or gasses then it should be a planet. It is too small to hold a heavy atmosphere of a specific pressure (i.e. O2, Nitrogen, CO2, etc) then it’s just a body.

No peace over Pluto

SpeakerForTheDead, Gilligan'sIsland(Miami), Florida — Mon, 16 Jun 2008 05:22:38 GMT

Omega, that doesn't work. As pointed out by many here, asteroids and comets are in orbit about the sun.
Stern said, "What if geologists or biologists couldn't make the simplest classifications, like animals vs. plants? It would be unacceptable."
Well, viruses have defied pigeon-holing for a very long time.
And paleontology has archaeopteryx - bird-like dino, or dino-like bird?
THIS is what makes science exciting and worth doing.

No peace over Pluto

SpeakerForTheDead, Gilligan'sIsland, Florida — Mon, 16 Jun 2008 05:28:11 GMT

By the way, I like the idea from Raleigh's Len: planetary classifications.

No peace over Pluto

Andy, La Plata, MD — Mon, 16 Jun 2008 12:35:40 GMT

Plutoid!?!? Even my spell checker doesn't like it.

No peace over Pluto

Tony Accardo — Mon, 16 Jun 2008 13:00:28 GMT

Oh for crying out loud. The term "planet" has no scientific meaning - it's from a word the Greeks used to described "stars" that "wandered" apart from the others. Public relations is the only reason the IAU is even keeping the word.

Yes, there are bodies orbiting stars that are not themselves stars or brown dwarves, are in hydrostatic equilibrium, and overwhelmingly dominate the mass of their orbital region, but that describes such a vast range of objects that it has no meaning as a category. Mass, temperature, and density all play strong roles in determining a body's characteristics, and the temperature variable is itself dependent on the particulars of the body's star, average orbital radius, and the eccentricity of that orbit.

Sometimes science is too conservative and tradition-bound for its own good. Just dump the term "planet" and come up with meaningful categories to describe these bodies so that we have an accurate, multidimensional continuum with significant delineations. Mercury has *nothing* of significance in common with Jupiter, let alone some of the monsters discovered around other stars, yet they are classed arbitrarily together simply because of the way the ancients saw them in the sky. How ridiculous.

In fact, none of the criteria currently proposed for planethood is meaningful. Why is Titan - the most Earth-like world known to exist - classed apart from Earth while Saturn - an object having virtually nothing in common with Earth - is not? Is it truly meaningful that Titan's primary orbit is around Saturn? If there were two Titans revolving around each other instead of one around a much larger body, would neither apply? What about if two bodies were of equal size, but one was vastly more massive? Which one is the "moon," and which the "planet"?

A modest proposal from a not-quite-layman: The following categories would be ample, though of course the actual names could be arbitrary, and each could be followed by numbers and letters describing various variables: Airless rocks I (odd); airless rocks II (regular, hydrostatic equilibrium); aired rocks; and gas bodies. The boundary between airless rocks II and aired rocks might seem arbitrary, since every significant body has a little bit of vapor floating around, but it could be said that an "atmosphere" is a *persistent* gas envelope (i.e., not a transient result of outgassing) sufficient to alter the solid surface in obvious ways. The boundary between aired bodies and gas bodies would be the absence of a solid crust - i.e., direct transition from atmosphere to fluid mantle. The upper limit of a gas body would be when fusion becomes a persistent process with significant effect on temperature.

Now doesn't this make more sense than calling everything from Mercury to TrES-4 a "planet"?

No peace over Pluto

m.frances, Laguna Beach, CA — Mon, 16 Jun 2008 15:04:17 GMT

Pluto is and has always been the furthest PLANET from the sun and those ding-bat scientist-wanna-bes that argue that it's not a planet are orbiting on a back road to trouble.
Nobody should have the right to slap new labels on old orbiting spheres such as Pluto.
Next thing they'll do is hit Walt Disney's Pluto and claim he's not a dog because he's yellow.
PLU-SHAW!
I will always consider Pluto our galaxy's ninth planet as well as considering those renegade scientists failures in how they conduct business.
PEACE - OUT!

No peace over Pluto

Dennis, Richmond, VA — Mon, 16 Jun 2008 15:46:22 GMT

If the Earth was in orbit around a gas giant, why could it not be both a planet and a moon? Planet just means Wanderer. I come down on the side of the geologists on this one. Look at what it is, not where it is, or what orbit it's in, or if it has cleared it's orbit... a duck is a duck, in a barn yard, in a school bus, or in a pig pen surrounded by pigs. It's still a duck. Now you have baby ducks, giant ducks, different species of ducks, and roast duck for dinner. Still duck, but with lots of variety. This would also be able to be easily extended to other solar systems (I hate the term exoplanet) as well as planets in no orbit at all.

No peace over Pluto

johanna,tukwila,wa — Mon, 16 Jun 2008 19:56:10 GMT

i just wanted to know why isnt pluto a planet anymore?

No peace over Pluto

S.B. Stein E.B. NJ — Mon, 16 Jun 2008 20:03:51 GMT

I would say that if it has enough gravity to have smaller bodies orbiting around it, then it could be considered a planet. I would have had a historical exception for Pluto.

No peace over Pluto

Laurel Kornfeld, Highland Park, NJ — Mon, 16 Jun 2008 22:21:44 GMT

At a time when we are discovering there is far more diversity to the universe than anyone dreamed of, we should be broadening, not narrowing, concepts such as "planet" to encompass the new data. Why not keep
"planet" as a broad category for objects with enough gravity to pull themselves into a round shape (hydrostatic equilibrium) and then divide those objects into multiple subcategories such as terrestrial planets, gas giants, ice giants and dwarf planets. The latter could be used to refer to objects that don't dominate their orbits yet are still planets. That way the dynamical considerations are still taken into account but they don't negate the equally important geophysical characteristics of these objects.

The reality is, the round moons of the planets, including Earth's moon, are geophysically very similar to the planets. Some have proposed labeling them as "secondary planets," meaning they orbit other planets instead of stars. To avoid confusion, we could simply continue to use the terms satellite or moon colloquially with the understanding that these terms refer to secondary planets.

Pluto, Eris, and other round KBOs are significantly different from the vast majority of tiny, shapeless Kuiper Belt Objects. Adding these and Ceres to the broad list of planets (or, more specifically, primary planets) might lead to as many as 200 planets in our solar system but not thousands. It's amazing to hear arguments that "we cannot have too many planets in the solar system" because children will have a hard time learning them. We don't limit the number of elements in the periodic table to make memorization easy. In any case, memorization is less important than a general understanding. It is far more productive for children to learn the characteristics of the many subtypes of planets than simply to memorize names.

What has too often been learned as a result of the IAU decision is an authoritarian view that "Pluto is not a planet anymore because my teacher says so" or because the IAU says so. Here is where Stern's points are especially crucial. The process by which we arrive at these definitions is just as important as the outcomes. A tiny portion of the IAU is trying to dictate by fiat what is essentially an interpretation, not a fact. That is highly problematic.

What is wrong with keeping the debate open until more data is available, especially since New Horizons and Dawn will give us this data in 2015? What is wrong with teaching that there are two or more schools of thought and having children and students do their own research and their own thinking so they can come to their own conclusions? This far more democratic approach is what the August conference will feature and hopefully will become a model for teaching this issue at all levels.

No peace over Pluto

Ian Mckay, Newport beach — Tue, 17 Jun 2008 00:17:42 GMT

Round, larger than rocks, orbits a star = planet

Orbits a planet = moon

pluto = planet

stuff that goes around jupiter = moons

please send all the money I saved to me now thanks.

No peace over Pluto

Troy, Auckland, New Zealand — Tue, 17 Jun 2008 01:39:01 GMT

Using an unbiased factor that I call the “Taos” index, we achieve the following index factors for the bodies in our solar system.

Planet Taos index
Pluto 7.28E-14
Moon 6.97E-13
Mercury 6.84E-09
Titan 3.97E-08
Mars 2.29E-05
Earth 1.00
Venus 1.43E+03
Uranus 6.21E+04
Neptune 1.09E+06
Saturn 2.90E+08
Jupiter 6.78E+09
Brown Dwarf 7.73E+12
Sun 2.69E+30

I used Earth an orientation reference and I included Titan and the Sun for external references. Anything with a Taos index above 1.0e+12 is a star and anything with a Taos index below 1.0e-8 should be classified as a “dwarf planet”. Even though Titan has a Taos index in the planetary range it doesn’t orbit a star it orbits a planet. So it would not count. If you look closely Mercury has a Taos index below the planetary qualifications so the debate shouldn’t be why Pluto is or isn’t a ”planet”, the data clearly shows it doesn’t classify, but we should really be looking at why Mercury is still considered a planet.

No peace over Pluto

Delmar Fairchild, Barron, WI — Tue, 17 Jun 2008 14:37:56 GMT

If stars are similar in make up and I think they all are similar, then they should be called "Stars". That name is as good as any.
We should call everything rotating around a star -"Objects". Earthlings have named the "objects" that orbit our "RA", Mercury, Venus, Earth, Mars, etc., from an age when people thought these objects were Gods looking down on us or named them after their Gods.
When we found the three "Objects" around HD 40307 we called them planets, but as of now, they are still "Objects" subjected to study, orbiting a star we named HD40307.

Reading from an earlier article by Alan, there is somewhat of a rule as to where these objects sit in the scheme of a solar system.

An object that rotates too close to its companion star and can not keep its atmosphere due to evaporation can be classified as "Solid Hot Objects" (SHO), those that orbit further out that have a slight gravatational advantage over the sun and can keep their atmosphere can be called an "Earthlike object" (EO), (We should have some leeway).
Those that revolve around in an area that has forces balanced to the point the atmosphere gets pulled out away from the surface by the sun or centrifugal forces, but yet is contained by the object's centripetal forces can be called "Gas Giant Objects" (GGO). Those that are frozen like Pluto can be call "Solid Cold Objects" (SCO). Of which we have a lot beyond that one we called Pluto.
If we want to we could name each SCO just to have something to do on our slow days.

No peace over Pluto

DP, NJ — Tue, 17 Jun 2008 17:10:18 GMT

IF Round THEN
IF Orbiting a star THEN
IF less than 1000 km in diameter THEN
IF stellar remnant THEN
It's an orbiting stellar remnant
ELSE
It's a Minor Planet
ELSE
IF fusion at it's core THEN
It's an orbiting Star in a multiple star system
ELSE
IF stellar remnant THEN
It's a orbiting stellar remnant
ELSE
It's a Planet
ELSE
IF less than 1000 km in diameter THEN
IF stellar remnant THEN
It's a stellar remnant
ELSE
IF it orbits a larger planet THEN
It's a Moon of a Minor Planet
ELSE
If it orbits a same-size planet THEN
It's a Binary Minor Planet
ELSE
It's a rogue Minor Planet (it's not in orbit)
ELSE
IF it's a stellar remnant THEN
It's a stellar remnant
ELSE
If it orbits a larger planet THEN
It's a Moon
ELSE
If it orbits a same-size planet THEN
It's a Binary Planet
ELSE
It's a rogue Planet (it's not in orbit)
Else
IF orbiting a star THEN
It's an asteroid
ELSE
IF orbiting a planet or minor planet THEN
It's a Moon (how about Moonlet?)
ELSE
IF orbiting a same-size asteroid THEN
It's still an asteroid (binary asteroid)
ELSE
It's a rogue asteroid (not in orbit)

Needs some further refinement, and contains some circular definitions that need to be worked out, but, here it is.

No peace over Pluto

Carl Bentley — Tue, 17 Jun 2008 17:44:17 GMT

Planet:
* Round because its mass can make it heavy enough to round the surface, or...
* Has atmosphere, and...
* Orbits a star (beause if orbiting a planet, odds are it will have VERY different sun light, gravity, magnetic field, etc. patterns)

This definition doesnt disqualify other objects that have athmosphere but are not round, I dont think the direction or the angle of the orbit should really matter.

No peace over Pluto

John Taylor — Tue, 17 Jun 2008 19:01:09 GMT

This is a tempest in a celestial teapot. There is no firm separation point between various classifications of space objects. All definitions are somewhat arbitrary due to necessity.

We have the inner rocky planets (earth like), the gas giants (Jupiter like), and the outer plutoids (Pluto like).
Why Plutoids rather than planets? It makes some of us feel better and will enable textbooks to stay up to date for longer periods because there is no doubt a significant number of Pluto like objects will be found, but is an otherwise meaningless distinction.

The current planetary definition about orbit clearing should simply be scrapped as unworkable, and the particular included objects comprising our "true planets" just named. Earth has not cleared it's orbit of NEO's. Neptune has not cleared it's orbit of that pesky Pluto and it's large group of 'friends' with similar paths and composition. We have no way to determine if any of the extra solar planets have as of yet cleared their orbits.

E-planets, J-planets, P-plutoids ... a far more sensible arrangement of names.

No peace over Pluto

Kelly NOdack — Tue, 17 Jun 2008 19:52:55 GMT

What makes a planet a planet? Too much explanation is not a good thing when one looks at all the objects in this universe

No peace over Pluto

Wayne, Denver,CO — Tue, 17 Jun 2008 20:19:48 GMT

This is the way we got "New Coke"! Some middle- management type sells a bright idea to the boss and it goes thru without too much more thought.Then when it hits the street everyone says "What were they thinking?" They weren't thinking they were brainstorming a publicity stunt to get attention. And they did.

No peace over Pluto

Wayne, Denver, CO — Tue, 17 Jun 2008 20:31:07 GMT

As AE would say, it depends on the point of observation. The moon orbits the sun by orbiting the earth orbiting the sun. So is it a moon and a planet? Is the earth a moon of the sun and a planet with a moon? We know that moonshine is only found on earth, but the IAU obviously found some!

No peace over Pluto

Bruce Jakosky, Boulder, Colorado — Tue, 17 Jun 2008 20:39:20 GMT

There are some key points that have not been brought out in this discussion:

Any time you're trying to take a continuum of objects and divide it into two classes, there's going to be a grey zone where the classification is ambiguous. No matter how "planet" is defined, there will be objects on one side of the boundary that reasonable people will think belong on the other side, and vice versa. For objects that have multiple characteristics (size, self-gravity, composition, location, internal or surface activity, etc.), the problem is exacerbated.

While it is possible to articulate a set of characteristics that, taken together, describe a planet, this is an arbitrary approach. Further, if we judge this set of characteristics by whether it properly places those objects whose classification we “intuitively” know, then those characteristics become equivalent to having a list of those objects that qualify and those that don’t. It simply is not possible to come up with a single, unique definition for a planet based on some objective scientific approach. This is a definition, and as such is arbitrary.

We’ve actually faced this problem before, in defining “life”: (i) There is no single, unique definition that we believe will apply to all life everywhere, and it may not be possible to objectively arrive at one. (ii) We currently “define” life by listing its characteristics, and we judge those characteristics by whether they properly classify those objects for which we intuitively know their nature; those objects that meet most or all of the criteria are deemed to be living. (iii) There are objects in a gray area between living and non-living, and reasonable people can disagree about their classification (e.g., viruses). (iv) While we have a set of criteria that comes close to defining terrestrial life (that is, based on RNA and DNA), this does not help us in identifying extraterrestrial life that might not use RNA or DNA.

In the end, the classification of objects is done by consensus. But consensus doesn’t mean unanimous opinion, and there always will be room for legitimate disagreement. Is the IAU definition of planet a useful one? It provides an interim classification scheme that helps scientists study the objects in our solar system. It’s certainly as defensible as any other definition. And trying to replace it with a different definition that is equally arbitrary but satisfies somebody’s preconceived ideas as to what should qualify seems pointless.

No peace over Pluto

SpeakerForTheDead, Gilligans Island, Florida — Tue, 17 Jun 2008 20:55:04 GMT

Troy, your "unbiased factor" using "Earth [as] an orientation reference" looks a little geocentric ;)
And as for dimissing Mercury as a planet, as noted by somewhere earlier, like Pluto it also lacks an atmosphere...but that idea just pisses me off even more :)

No peace over Pluto

Dennis, Richmond VA — Tue, 17 Jun 2008 20:58:57 GMT

The thing is, if you want Pluto to be a planet, then you have to call Eris a planet as well... it's bigger than Pluto.

No peace over Pluto

SpeakerForTheDead, Gilligans Island, Florida — Tue, 17 Jun 2008 21:36:30 GMT

Troy, your next post I'll call "biocentric". The term "planet" should be defined based on geologic considerations, not biologic.
We know of no "life in any form" that would be happy (or even living for long!) stranded on Venus.
Soon we'll have excluded every body in the solar system from qualifying for planethood-except Earth, of course.

No peace over Pluto

SpeakerForTheDead, GilligansIsland(Miami), Florida — Tue, 17 Jun 2008 21:49:41 GMT

oops...I meant my last post in response to Troys FIRST (not last) post. Sorry for my confusion.

No peace over Pluto

Will Davis, Sunnyvale, California — Wed, 18 Jun 2008 06:00:40 GMT

Renaming bodies like Pluto is an awful lesson example for our children. If an adult person grew to a hight of under four feet, has a large forehead, and stubby fingers, do we call such a person a subhuman? Absolutely not! So why do we call a body that is smaller than the others, has an offset orbit, and crosses paths with a "big" planet, a Plutoid, or whatever? No, round bodies that orbit the parent body are planets!

No peace over Pluto

William Jones, Columbus, Ohio — Wed, 18 Jun 2008 14:18:31 GMT

With due respect, I disagree with virtually every statement made by Alan Stern.

For example, take this one:

"What if geologists or biologists couldn't make the simplest classifications, like animals vs. plants?"

Fact is biologists continue to beat their heads against walls trying to determine how many kingdoms there are, how to classify algae, and so on. Taxonomy did not end with Linnaeus. It's more complicated than ever. I like the desert island analogy. Biologist were forced to confront new worlds only very recently when new communities were found, for example, living near hydrothermal vents and in other extreme environments.

So, while Dr. Stern brings up interesting points, I question his motivation. Does he feel the object that helps pay his salary through research grants (the planet/dwarf planet/plutoid called Pluto) simply needs more "respect"? His reaction seems a bit over the top. Since when did this become personal?

No peace over Pluto

Lee Blake, Fairmont, WV — Wed, 18 Jun 2008 20:37:38 GMT

Here's my question... What about Saturn? It has some well known "debris" surrounding the planet. So it is clear that Saturn has yet to clear it's surrounding space. Therefore it is not a planet. And also Jupiter and Uranus have rings too, so they're not planets either.

This is just ridiculous. I'm in complete agreement that the definition needs to be much "simpler." If a body orbits a star, is approximately round, and is greater that Xkm in diameter (or some other easy to identify characteristic) then it's a planet. If it's between Ykm and Xkm and is round then it's a planetoid. If it's not round or smaller than Ykm, it's an asteroid. If it orbits a planet, it's a moon.

No peace over Pluto

Tim Rommes, Washington, UT — Wed, 18 Jun 2008 23:42:26 GMT

Regarding Gordon Freeman's comment. The "round" requirement is, more fully, having sufficient gravity to approximate roundness. Simply put, no cigar shapes. To be a planet it would have to have strong enough gravity to pull in the ends of the cigar. This says a whole lot more than a simple measurement and is far less arbitrary.
I also think that a stable orbit is important, a planet is a resident, not a wanderer.
If it's in orbit, even half a co-orbit, then I don't see why a dead star wouldn't be called a planet with some history. After all, every planet used to be a star, or part of a star.

As for Troy's comments, I don't think life is that important in it's being a planet. This would fall in as one of the categories of planets. Same with atmosphere, especially since the ability to hold an atmosphere depends greatly on conditions outside the planet. Solar wind in particular. Mercury has had it's atmosphere blown away, it's too close. Saturn, in Mercury's orbit, would have it's atmosphere blown away, as it continued to get more atmosphere by conversion, until it left an Earth sized rock without an atmosphere. The question of mass answered by roundness is far less arbitrary than whether or not it has atmosphere.

No peace over Pluto

Tim Rommes, Washington, UT — Wed, 18 Jun 2008 23:45:45 GMT

Darn! The other thing from Gordon. The fact that an asteroid may have been pounded into roundness isn't the same as it's own gravity crushing it to roundness. Otherwise, yes, a lot of river rocks could be planets. Grains of sand. Macedamia nuts. Baseballs.

No peace over Pluto

John C. Carter, St. Petersburg, FL — Thu, 19 Jun 2008 02:56:10 GMT

The attempt to use "scientific" dividing lines to delineate categories in such a gray area is at best an exercise in futility and at worst, ridiculous.

Even CalTech's Mike Brown (discoverer of 2003UB313 aka Eris), while an initial advocate of Pluto's "demotion," made a valid point on behalf of the cultural desire toward Pluto's retention of planet status in a web article located at:

http://www.gps.caltech.edu/~mbrown/planetlila/

The next three paragraphs are quoted from his website. Note especially the analogy he draws in the 2nd paragraph using the word "continent":

"In my view scientists should not be trying to legislate an entirely new definition of the word 'planet.' They should be trying to determine what it means. To the vast majority of society, 'planet' means those large objects we call Mercury through Pluto. We are then left with two cultural choices. (1) Draw the line at Pluto and say there are no more planets; or (2) Draw the line at Pluto and say only things bigger are planets. Both would be culturally acceptable, but to me only the second makes sense for what I think we mean when we say the word planet. In addition, the second continues to allow the possibility that exploration will find a few more planets, which is a much more exciting prospect than that suggested by the first possibility. We don't think the number of planets found by the current generation of researchers will be large. Maybe one or two more. But we think that letting future generations still have a shot at planet-finding is nice.

"Astronomers tend to dislike this solution as it is clearly non-scientific. The best analogy I can come up with, though, is with the definition of the word 'continent.' The word [sounds] like it should have some scientific definition, but clearly there is no way to construct a definition that somehow gets the 7 things we call continents to be singled out. Why is Europe called a separate continent? Only because of culture. You will never hear geologists engaged in a debate about the meaning of the word 'continent' though. When geologists talk about the earth and its land masses they define precisely what they are talking about; they say 'continental crust' or 'continental drift' or 'continental plates' but almost never 'continent.' Astronomers need to learn something from the geologists here and realize that there are a few things -- like continents and planets -- to which people have large emotional attachments, and they should not try to quash that attachment.

"Thus, we declare that the new object, with a size larger than Pluto, is indeed a planet. A cultural planet, a historical planet. I will not argue that it is a scientific planet, because there is no good scientific definition which fits our solar system and our culture, and I have decided to let culture win this one. We scientists will continue our debates, but I hope we are generally ignored."

[End excerpt]

As Mike mentions, Pluto--as a planet--is part of our culture. Why not just accept that and move on? And if the scientific community still insists on having a scientific consensus to such an unscientific bit of nomenclature, then why not let the FULL membership of the IAU (~10,000 members, last I heard) decide, rather than glean their "scientific conclusion" from a tiny minority as was done in 2006? Otherwise, how scientific is that?

Pluto has been defined by our culture, and our culture has deemed it a planet. Onward and upward, everyone.

No peace over Pluto

Troy barsten — Thu, 19 Jun 2008 03:52:58 GMT

My comments were in no way meant as "bio" or "earth" centric. It is just a way to start with objective evidence rather then speculation. The TOAS factor I introduced is based on 7 different cartelistic none of which is based on the possibility of life. There is always going to be transitions stages like water turning to ice. Planets turning to stars, etc. I just wrote an equation to approximate that process.

No peace over Pluto

Tim Rommes, Washington, UT — Fri, 20 Jun 2008 14:36:49 GMT

Troy,
In your post of 6/18, 2352, I'm assuming you meant to use characteristics instead of cartelistic, or maybe there is a definition of cartelistic that I don't know. If so, please help me out.
Perhaps listing the 7 characteristics would shed light on things, but otherwise, how do you arrive at points of differentation? As far as I can tell your system is just as arbitrary as any other. I could come up with a system based on infromation such as color, or reflectivity, or apparent brightness and pick points but would they mean anything? Your upper limit for a mass that could sustain a fusion reaction is meaningful but how do you arrive at the lower limit for dwarf planets? It does us no good to replace one arbitrary system with another. Personally, I'm all for the lower limit being sufficient to approximate roundness, but that seems to be much lower than your limit. If there is an observable reason for your points I'm interested in knowing what it is.

No peace over Pluto

Tim Rommes, Washington, UT — Fri, 20 Jun 2008 14:50:01 GMT

I don't think "hydrostatic equilibrium" means what previous posters think it means. It doesn't apply, at least to the best of my knowledge, where physical structure, like we get from solids, is holding a body out instead of pressure, like we get from fusion in a star.
I have used a phrase, not my own, "sufficient gravity to approximate roundness" that means that it's able to reorganise it's solids, sometimes even breaking them with gravitational force, to come to a roundish sort of shape. This would be a different amount of gravity for different materials of different strengths, so it would be difficult to pick one particular value. Instead, enough hard rock to pull itself to round would be much more mass than enough meringue to pull itself into round. As the composition varied the mass necessary would also vary, and there would always be a debateable area as to whether it happened to be round for other reasons or whether there is actually sufficient gravity to account for it's roundness.

No peace over Pluto

Tim Rommes, Washington, UT — Fri, 20 Jun 2008 15:07:46 GMT

Lee Blake,
By capturing its moons or other debris in its orbit a planet has cleared them from its path. They are locked into its gravity, which can be said of the rocks on earth. The distinction here is that moons and other debris are not in physical contact with the planet.
Another interesting point on that, there are several points surrounding a planets orbit where that planet can "hold" matter in a gravitaional lock shared with the sun. I can't remember what those points are called, but we already know I can be vocabularily challenged. I think there are six points total, and the matter in them orbits the sun, not the planet, under the gravitational influence of the planet. Outside the planets orbit on the same solar radius as the planet, where the planet's gravity falsely adds to the sun's. Inside the planets orbit on the same solar radius as the planet, where the planet's gravity falsely subracts from the sun's. Two points on the planets orbital path some number of degrees from the planet where the math is a little harder to understand. And, maybe, two more points, but gosh.
Arguably, all have been cleared from the planet's orbital path. Some rocks fall to the surface, some get locked in planetary orbit, some get locked in solar orbit, but none are doing their own thing.

No peace over Pluto

Kyle White Pensacola, Fl. — Fri, 20 Jun 2008 15:30:06 GMT

What about the rumors that one of theses plutoids will pass very close to Earth, causing a possible slight pole shift, fact or fiction ???????

No peace over Pluto

Tim Rommes, Washington, UT — Sat, 21 Jun 2008 06:56:59 GMT

Kyle,
It's possible for many of the KBOs to have orbits that coincide with earth's. That's a big "where we got our oceans" theory. Haley's comet is a KBO and has a period of 75 years. So I'd guess that we've already seen, or at least had the opportunity to see any KBO that has a killer track, or else it's on such a long orbit that it has to pass through so substantial an amount of the kupier belt that it's likely to have it's orbit changed by collission. Which also means that there's a lot of stuff not on a collission course that could be knocked onto one. So I'd guess that if there was anything of substantial enough size to effect our planet gravitationally we'd all already know about it. It's the oort cloud that will catch us unawares.
A few years back we were near missed by an asteroid with no effects that I've heard of. In the seventies a large meteorite skimmed the atmosphere and the earth didn't flop. It would take a very large object, probably with a substantial magnetic field, or a direct hit to effect us like that. And if it's a direct hit, even in water, then you won't care about a pole shift.
More probably an object would be able to alter the moon's orbit and wreak havoc on earth. Weird tides, we wouldn't know when to harvest, eclipses at weird times, I'd freak out cause we'd probably get to see the rest of the moon. Who knows what effects an over the poles lunar orbit would have on us? Or what the effect would be from seeing a relative lunar rotation? Are there forces at equilibrium with the same face toward us that would vary if the lunar poles were toward us? At different times of the month, of course. And a month might only take a week. That close and high tide might sweep over the continents.

No peace over Pluto

Helena McCoy, Atlanta, GA — Sun, 22 Jun 2008 10:01:06 GMT

I don't see why they can't just classify planets the way they classify everything else. A dwarf star is still a star, right? So why is it any different with planets?

Personally I agree that they should have a classification system similar to that in Star Trek. Kirk and Spock never sit around debating the details of, for example, a Class M planet. It is what it is, regardless of the size. That's the idea. Of course there would be updating because that's just part of science, adapting to new data, but I hardly see any reason for things to get so excessively technical.

And in my humble opinion, I think the term "dwarf planet" is perfectly acceptable. Calling anything a "little planet" or "little star", as politically correct as it may be, would just be taking things too far. A sensitive, emotional human is one thing. A non-sentient object in space is entirely different.

No peace over Pluto

Tim Rommes, Wahsington, UT — Sun, 22 Jun 2008 22:14:31 GMT

On Star Trek the planet classification system is far more technical than what we're talking about here. To be classified "M" a planet must be roughly similar to Earth. Gravity (size), composition, atmosphere and temperature all must be similar to ours. In addition, the planet would invariably have to have a magnetic sheild, otherwise the solar wind would strip the planet of atmosphere - it must be within a distance from it's star that maintains the right temperature - and it would be too highly irradiated. The possible exeptions to the shield / radiation problem would be a planet orbiting a red dwarf in close proximity or a rouge "planet" that falls into the orbit of a white dwarf "star."
Which brings up the white dwarf star is still a star question. Whether or not it's a star depends on the definition of star, much like the planet question. A white dwarf is basically a hot rock, so hot it glows. If a star is defined as "self-luminous" the a white dwarf is a star. Of course, coals from a fire or a red hot poker would be "Earth bound stars." But the red hot poker would only be a star on the end you don't hold. If a star is defined as "a mass in hydro-static equilibrium" then a white dwarf is not a star. I'm not sure what the scientifically accepted definition is for a star, but you have to interperet it technically. Same for planets lest we start calling shooting stars stars.

No peace over Pluto

Tim Rommes, Washington, UT — Sun, 22 Jun 2008 22:30:45 GMT

Oh, shoot. And a brown dwarf isn't a star by any definition I know of. It would be a rogue planet, so all those bodies that used to be it's planets would now be moons, maybe "rogue moons." In any event they'd all be "dark matter," although not the mysterious kind. What would we call those bodies that used to be moons of the used to be planets of the used to be star?
All of it's technical definitions. Those definitions should, star, planet, nebula, etc. should address a set of basic characteristics that are common to the thing described and unique to that division of cosmic blob. For a star should we go with self luminous or sustaining fusion? For a planet is stable orbit important? Questions of this level need to be fairly general. Subcategories of stars or planets are where the finer questions need to come in.

No peace over Pluto

Sensible, PV, AZ — Mon, 23 Jun 2008 00:15:08 GMT

We need to leave Christopher Columbus out of this. He's another whole topic of debate.

The scientists who specialize in planets should make the decisions on what the definition should be. Not the IAU. Tony's mention of forming an International Planetary Union - or IPU, is a great idea.

However, with that being said, I don't think there is anything wrong with getting input from other folks as well. Sometimes I hear some pretty lame determinations by so called "specialists", only to hear a few months later, that a different scientist with a little more common sense corrected the previous determination and gave a more plausible observation. Hey, if they're wrong, they were wrong. IAU... quit trying to save face, and fix it, or allow another group that is more specialized in that area to do so. It just looks stuborn and pig headed to hold onto a definition that does not make sense, that anyone with even a minute amount of scientific knowlege can see is wrong - regardless of the outcome. GB

No peace over Pluto

Heather erie pa — Mon, 23 Jun 2008 08:48:18 GMT

Planets are also classified as a rock that has compacted itself so much it became round. Now pluto is a round "rock", but I agree that it should have an atmosphere and rotate around a star. If it doesn't then it is a plutoid. Now to classify a round "rock" that circles a PLANET then that is a moon, as long as it has an orbit around its planet. I believe all this fighting over a planet is not worth it. We are discovering new planets almost everyday and some of them are breaking the laws of what we knew about planets and solar systems. Like the new Super Jupiters. If we classified them by current standards they would not fit to scale. Like I said if it is round, has an atmosphere, and orbits a star then it is a planet.

No peace over Pluto

Troy, Auckland, New Zealand — Mon, 23 Jun 2008 20:40:04 GMT

Tim,

Yes - I meant “characteristics.” :)

Without going into too much detail, I plotted the TOAS data and then normalized it to derive a "generic" equation. Y=8x10^-50*X^(12.32). Where X is the radius and Y is the normalized TOAS Factor. When you normalize the data it become apparent that smaller Plutoid Dwarf Planets (PDP’s) are outliers as at 10^-8 much as fusion reaction gas giants @ 10^+12.

I didn’t say that the above is the best method but it’s a starting point based on objective evidence rather then subjective characteristics.

No peace over Pluto

Tim Rommes, Washington, UT — Tue, 24 Jun 2008 13:45:04 GMT

Troy,

That's interesting because it addresses the way planet formation groups together. I am thinking of our system starting from a rotating ball of gas and debris cast off from a dying star. From there it condenses down to what we have today. The major component of that would be the sun. I wonder, if you tracked back to the formation of the sun and used that pre-fusion data would your distribution curve tell us anything about system formation. Could we manipulate it for larger, smaller, faster rotating, different composition seed clouds and predict what the resultant system would look like? Be able to work backwards from now and develop a map over time of where all the stuff came from and tell what the precurser events were. Super stars that can only form when those clouds are extremely dense, first generation stars that all died off together, insight into dark matter? Does your data offer any insight into the formation process? Was Mars trying to be a gas giant but was too close to the sun so only the rocky parts remain? I wasn't able to find anything on TOAS factor. Is there any place I can read up on this?

No peace over Pluto

Troy, Auckland, New Zealand — Tue, 24 Jun 2008 22:07:31 GMT

Tim,

The TOAS factor is my own creation. I had to call it something. :)

While everyone was arguing whether planets are round, white, made of cheese, etc. I just formed a set of 7 criteria that any object would exhibit that a majority of scientist might agree would be needed to form a planet.

The idea was that heavily bodies could go through phase changes like water. If so, specific planetary radii, mass, etc. would be significant to hold and maintain some form or measurable atmosphere. I focused on atmosphere specifically because it seems to be necessary but not sufficient factor in locating potential “earth like planets” else where, and at a critical mass the atmosphere might begin the fission process to become a Star. As I plotted the data it seems that under a specific critical radius an objects ability to maintain any significant atmosphere decreases exponentially. When you plot the data you can actually see the planetary band develop. There will always be gray areas (i.e. Mercury) but I’m sure exceptions can be made to planets whose orbit is so close to Stars that they are stripped of their atmosphere but if they were further way in a more “habitable” zone then they would easily maintain the atmosphere necessary for planetary status.

Using this to model solar system development is intriguing. If you’re more interested in exploring this idea further or possibly publishing this idea then leave a generic contact detail and I will share what I have. It would be nice to refine the theory more.

No peace over Pluto

Tim Rommes, Washington, UT — Thu, 26 Jun 2008 01:41:40 GMT

Definitely interested in pursuing this further. It's been an idea bouncing around in the back of my head for some time. rommestim@aol.com. If that gets edited it's my lastfirst at America on Line. Looking forward to hearing from you.

No peace over Pluto

Paul Cartwright, Shropshire, England — Fri, 01 Aug 2008 02:29:57 GMT

A rose by any other name. The numerous connections being made by people between the necessary parameters of determining one class of objects from another to those which determine living organisms, such as a rose from a tulip, mark out visibly the central nature of the confusion - caught half way between wanting a clearcut definition guide based on the way a star system looks and on the other hand the way it evolved. It is however because of the arbitrary evolution of such a thing as a region of space as compared with the carefully guided self-manipulation of life's proponents that no such clearcut system can be denoted based solely upon this. An approximate yet reasonably self-consistent balance between these to underpinnings of definition needs first to be established, e.g. Regardless of Pluto's distance from the Sun, should all Oort cloud objects (based upon their common age) be thusly considered collectively unique.

No peace over Pluto

Christian Christensen, Denmark — Sun, 11 Jan 2009 22:44:00 GMT

I loved to read all the interesting opinions on this topic.

Let me add my two cents:

Having read all the comments, I found it very strange that nobody comments on what is, in my opinion, the strongest point that Stern makes, namely this:

Scientists expect, he says, to find large objects somewhere in the deep outer solarsystem.
Imagine, as he says, that an earth-sized object (or even larger, we might add) is found orbiting at, say, 60 AU.
Imagine further that its orbit is circular and sits nicely on the ecliptic plane like the other 8 planets.

There is absolutely no doubt that such an object, fitting so nicely and tidyly into the planetary system as it does, would be considered a planet, no matter what the Stern-Levinson parameter or any other formula would have to say about it.

If (when?) that happens, the IAU will have to modify their definition to accomodate this new object.

The definition, therefore, seems to be insufficient from a philosophical point of view: it clearly doesn't capture our conception of what would constitute a planet.

On the other hand: we're not philosophers, but scientist. The definition adequately describes what we KNOW, at this point in time, to be scientific fact (as opposed to what we speculate about). It is true that once new data is in, we may want to change our definition in the light thereof, but that is not the situation we are in now. As long as new data isn't in, we should keep, as Popper would say, a definition that - while correct - is as ambitious and easy-to-falsify as possible.
That seems to me to be just standard scientific method. In fact: wouldn't it be UNSCIENTIFIC to allow for a planet such as in this example until we KNOW that such planets really exist?

All in all:

I don't mind the new definition. Let's keep it until it becomes clear that it's wrong, and then change it. As we always have. That's just science, isn't it?