Pluto defines a Planet as being a Planet!

silylene old · Sep 24, 2006

A supergiant planet is high enough in mass that it contains degenerate matter in its core, but low enough in mass that at no time can it become a star. Well I never saw the Stern & Levinson paper. I am happy to see commonality with my proposed definition (earlier in this thread, and in fact posted pre-SDC crash here about 2002), which included a discussion of the quantity of degenerate matter in the planetary core, is a valid consideration in planetary definition. <div class="Discussion_UserSignature"> <div class="Discussion_UserSignature" align="center">- - - - - - - - - - - - - - - - - - - - - - </div><div class="Discussion_UserSignature" align="center">I really, really, really miss the "first unread post" function. </div> </div>

rhm3 · Sep 24, 2006

Regarding Earth as a dwarf planet...the public may outcry, but they'd have no reason to be upset other than the fact that it ruins their comforting conception that the Earth is actually a large celestial object. But that conception is false, so I think it'd be beneficial and help people realize that Earth really does pale in comparison to the dominion of gas (giant) planets. Alternatively, the whole physical categories could be left out of public awareness completely and just focus on major, minor, secondary, and isolated. That might be easier to understand. Also, I don't see the harm in accepting moons as planets. Aside from Luna, round moons in general are highly underrated by the public (how many people actually know anything about Europa and Titan?). Again, calling them planets would be beneficial and help people draw the mental image of what they truely are: worlds. Luna is a secondary dwarf planet (or just secondary planet)...I'd abandoned the term moon as an official classification unless you're using it as nickname to explain the concept other Lunas...i.e., other Moons.

rhm3 · Sep 24, 2006

Yeah I think that serves as a good boundary between giant and supergiant planets, it's an important physical change in an object. I know I read your posts about it, and I think I saw it somewhere else, but Stern & Levison didn't mention it (they had all of the divisions based on arbitrary mass limits I believe).

kheider · Sep 24, 2006

>Alternatively, the whole physical categories could be left out of public awareness completely and just focus on: />major= Planets >minor= 'Dwarfs Planets' >secondary= moons >That might be easier to understand. That is more or less the system now in place. I agree that it might be best to consider the largest moons as planets. But that would open a whole another can of worms. -- Kevin Heider

jakethesnake · Sep 24, 2006

I was wondering how Friday’s debate about Pluto went at the observatory and, if you could please try to give an objective point of view? If you could describe the strong points of both sides as you saw it, I would be very interested in reading about this. <div class="Discussion_UserSignature"> </div>

rhm3 · Sep 24, 2006

Yeah but I really dislike the term dwarf planet. For one, it implies planethood (I know it's a compound noun but not many people "get" that at first read). Secondly, it also implies "small planet." But that's not what it defines...it defines a dynamically-insignificant, ahem, "planet." Here's a question I'm curious to see if someone can answer. If a moon has to orbit a planet, and a planet has to orbit star...what do you call a planetary object not in orbit around anything? What do you call an object that orbits it? Interstellar planet and interstellar moon may be fine but...just like dwarf planets...they're oxymorons. This is why I think anything under the star limit and gravitationally round is a planet. Then we can have many different ways of grouping them based on orbit, physical traits, size, etc. But they're all planets. I should also clarify that under the classification idea I posted above, the term satellite still sticks. Anything that orbits another object (planet, star, asteroid, etc) is a satellite of that object. This makes it convenient to discuss all the objects in orbit around a given planet without having to worry about which ones are round or not (e.g. I observed many satellites of Saturn last night). Chances are many of those were secondary planets (mental image: round world).

MeteorWayne · Sep 25, 2006

Wayne, Had a busy weekend, so haven't had a chance to write up a report yet. Quick summary, we took a vote before and after <img src="/images/icons/smile.gif" /> Before: Pluto Planet? Yes 11, No 2 After: Pluto Yes 9 1/2, No 3 1/2 I'm still working on pushing that half vote to the dark side <img src="/images/icons/smile.gif" /> It it the President of the NJAA <img src="/images/icons/wink.gif" /> Eveyone enjoyed the presentation, and we got a standing ovation of appreciation at the end. Afterward, my counterpart and I continued the discussion over a fine selection of craft brews. I will update some of the Pluto Perspectives, since that's where I made my inroads. My Master list now includes the 183 largest sun orbiting objects (plus Jake), including 23 Plutinos. The full list of 183 is too large to list, so I'll have to whittle it down somehow. If anyone would like my full current list (It's now over a week old, so probably obsolete), it's an excel workbook with 2 sheets, one sorted by size, the other by semimajor axis and orbital period. Unfortunately it's 110 kb so too large to attach here. My personal thoughts on the experience will be posted soon, and I'll even ask PlutoPlanetBoy for his reactions, and will post them if he replies. Briefly, Pluto is a planet came down to: A. It's always been a planet B. Mass Pluto's not a planet came down to. A. There's 23 Plutinos, it's just the largest one. <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

robnissen · Sep 25, 2006

Exactly.

kheider · Sep 25, 2006

Wandering Giants (July 2006): "From the dust and gas disc of the very early solar system emerged the gas giants. Four billion years ago our solar system looked quite different to the one we see today with Uranus and Neptune much closer to the sun, regularly swapping orbits. Patrick Moore discusses how these wandering giants came to be flung to the icy outer regions of our solar system." Also learn how they believe that Triton was part of a binary KBO system and that Triton was most likely the less massive of the system. I just thought with all this talk about Pluto that some might enjoy watching the program. (click here to see the list of BBC programs) -- Kevin Heider

MeteorWayne · Sep 25, 2006

This Gas Giant migration theory was discussed in Science or Nature about a year ago. Have you seen the program? I was wondering if they included information of the apparant Kuiper Belt cutoff at ~ 50 AU, which is still confirmed by th latest data...though that could change <img src="/images/icons/smile.gif" /> Regarding Triton, the latest report, IIRC from a few months ago did not indicate much of a preference for Triton being the more or less massive of the binary. It had more to do with which one of the binary pair was revolving about the barycenter in a direction opposite to it's heliocentric motion. This would give it a slower speed relative to Neptune, making it easier to capture. I wonder if they had some more recent simulations. <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

jakethesnake · Sep 26, 2006

Thanks Wayne for the low down on the debate and I look forward to your report on what happened. It sounds like it was a very professional event and a great time especially the continued discussion over a fine selection of craft brews! P.S. You weren’t trying to persuade the pres. with that fine selection of crafted brews were you because that would mean you are on the dark side? <img src="/images/icons/cool.gif" /> <div class="Discussion_UserSignature"> </div>

MeteorWayne · Sep 26, 2006

No Jake, the brews were with PlutoPlanetMan. The president I'll work on one night out under the stars <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

jakethesnake · Sep 27, 2006

Check out who signed this petition, they seem to be a pretty heady crew with some very good credentials. Petition Protesting the IAU Planet Definition We, as planetary scientists and astronomers, do not agree with the IAU's definition of a planet, nor will we use it. A better definition is needed. SIGNATURES (Final - August 30, 2006 6 AM PST) [PDF]<img src="/images/icons/shocked.gif" /> http://www.ipetitions.com/petition/planetprotest/ <div class="Discussion_UserSignature"> </div>

MeteorWayne · Sep 27, 2006

I agree, Jake, but I'll bet a petition in the other direction would have just as many, and at least as prominent names. BTW, the format of this petition signers stinks. It's not alphabetical <img src="/images/icons/smile.gif" />I have to try and import it into excel for sorting. In the meantime, I'll print it out and read through to see who I know <img src="/images/icons/smile.gif" /> I only recognized 3 names at first glance. Carolyn Shoemaker and Steve Ostro, who's opinions I respect immensely, and Tom Van Flandern, who's opinion I do not. (Do a google) I did not notice anyone from the Minor Planet Center, who know more about what stuff floats about in the Solar System than anyone. Nor did I see too many names I know at JPL, other than Steve. There were several significant omission from the JPL solar system scientists as well. And the few people I have known who work in this area were not listed. Steve Squyers was not listed... I could go one, but a petition is just that. A list of people who want to try and change something. I have no problem with that. And the goal is fine with me. "Planning is underway to establish an open and inclusive grass-roots process by which planetary scientists and astronomers from around the world can approach a better resolution to the issue of planets in our own solar system and elsewhere, with every step and discussion in public view. This process should culminate in a conference, not to determine a winner, but to acknowledge a consensus. The discussion will be wide ranging and should offer the public a fascinating and educational view of scientific discourse on a topic to which they can all relate. " That last part is what we do here <img src="/images/icons/smile.gif" /> <img src="/images/icons/laugh.gif" /> <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

nexium · Sep 27, 2006

In my opinion, the IAU has done enough damage with their ill conceived definitions. The 100 or so classes of astronomical objects in common use for decades is sufficient, even though it is vauge on some points. I'm strongly opposed to 1000 plus classifications such as super giant planet, giant planet, sub giant planet etc. Next we will be clasifing microscopic bits of dust as large, small, medium and single molecule. Neil

jakethesnake · Sep 28, 2006

I agree that there are probably many scientists that support Pluto’s demotion yet this list definitely highlights the flimsy definition of what a “Planet” is. <img src="/images/icons/wink.gif" /> The goal is also fine with me and at the very least the definition of “Planet” has caused this debate world wide so, I can wait three years until Pluto gets it’s planetary status back. <img src="/images/icons/laugh.gif" />. <div class="Discussion_UserSignature"> </div>

vonster · Sep 28, 2006

<blockquote>In reply to:<hr />You think "clearing its neighborhood of comparable objects" is difficult to explain? Try explaining the oxymoron "Major Dwarf" to the general public<hr /></blockquote> hahaha.. yeahh .. I think just killing off the word "dwarf" in reference for planets, and leaving them for stars would probably be a really, really good start. If nothing else, that. Please. Its not working. .

jakethesnake · Sep 29, 2006

I agree the notion of a “Dwarf Planet” kind of makes me want to pull my hair out. <img src="/images/icons/crazy.gif" /> It’s akin to saying a human that is a dwarf is not a person and the word “Dwarf” denotes size not composition. I think the usage of the word underscores the lack of knowledge that went into the IAU’s planetary definition. <img src="/images/icons/rolleyes.gif" /> <div class="Discussion_UserSignature"> </div>

silylene old · Sep 29, 2006

Based on our knowledge of over 200 exo-planets, perhaps Earth and Venus should also be considered to be dwarf planets . Oh, I agree with you, I too hate the usage of "dwarf" refering to planets. <div class="Discussion_UserSignature"> <div class="Discussion_UserSignature" align="center">- - - - - - - - - - - - - - - - - - - - - - </div><div class="Discussion_UserSignature" align="center">I really, really, really miss the "first unread post" function. </div> </div>

jakethesnake · Sep 29, 2006

I think you’re basically right and what the IAU is doing is categorizing everything to divvy up the data so, that it is more manageable throughout the various fields of study in the astronomical community. I have no problem with the distribution of data but, what I do have a problem with is the total lack of scientific knowledge that the IAU is using to disseminate a definition onto the public. Let them break things up as they wish but don’t lay down a definitions without at least a little scientific prudence. <img src="/images/icons/rolleyes.gif" /> If you don’t know don’t add to the confusion! If you don’t know leave it alone until you do! If you don’t know admit it! If you don’t know don’t cost everyone a lot of money pretending you do! <img src="/images/icons/wink.gif" /> <div class="Discussion_UserSignature"> </div>

kheider · Sep 29, 2006

Mercury is so close to the Sun that it does not have much of an atmosphere even though it is 23x more massive than Pluto. Pluto has a non-circlier orbit that varies from 29-50AU from the Sun. Pluto only has an atmospehere when it is near it's closest point to the Sun. When Pluto drifts back out further into the solar system that very thin atmosphere will freeze to the surface. Pluto is estimated to be roughly 60% ice and 40% rock. If Pluto were orbiting were Mars is today, a lot of Pluto's mass would burn-off and escape Pluto's weak gravity. This scenerio could very well be another reason to compare Pluto to Ceres. Ceres and Pluto are both Belt Objects surrrounded by many other comparable belt objects. The term 'Dwarf Planet' is not a bad way to make these large planetesimals stick out from the lesser asteroids. "Mercury (which modern science has shown to be the smallest planet) has been known as a Planet for thousands of years, were as Pluto has NOT even been known for 100 years."<img src="/images/icons/smile.gif" /> -- Kevin Heider

jakethesnake · Sep 29, 2006

Kevin You have a very good point in that there are many various type of celestial bodies in our solar system, some of which are called moons and if they were solely orbiting the Sun they would no doubt be called a “Planet” with little or no difference except for their primary orbits. The diversity is no doubt vast and all I’m basically saying is the cutoff that annexed Pluto from planet hood was not based on anything scientifically tangible as far as a specific cutoff. One could imagine an unlimited distribution of celestial objects throughout the universe, some comprised solely of water ice, gas, iron, rock and, so on, these celestial objects would also be affected depending were they are within their solar system. I’m sure the distribution of composition, size, and orbital variation are endless but, these are all things that can be categorized scientifically and albeit with various levels of educated arbitrary definitions at least they can clearly be defined. Clearly define the difference between a “Dwarf Planet” and a “Planet”! The IAU couldn’t do it can you? Also I can live with the definition of “Dwarf Planet” if I have to but, not the definition that separates a “Dwarf Planet” from a “Planet"! <img src="/images/icons/laugh.gif" /> <div class="Discussion_UserSignature"> </div>

jakethesnake · Sep 29, 2006

Very well put! <div class="Discussion_UserSignature"> </div>

kheider · Sep 29, 2006

If one were to put ANY of the gas giant planets where Mars is they'd shed their atmospheres like a dandelioin does its "fluff" in a high wind. Jupiter is 3x farther from the Sun than Mars. But if you put Jupiter were Mars currently is, Jupiter, with it's large gravity & magnetic field would hold it's own quite well. Any of the large Jovian Planets (if placed, in their current form, where Mars is today) would hold onto the a lot of their mass. The KBOs (oversized dirty snowballs) would basically vaporize away if they were placed were Mars is. If Pluto were placed were Ceres is, Pluto would look and act a lot like Ceres in a billion years. the standard term was 'major' planets meaning all 9 of them and the 'minor' planets' meaning the asteroids and such. That would avoid the connotations of 'dwarf' and 'giant', which would be fine with me. Pluto is no longer defined as a planet and the term 'minor planets' has been dropped in favor of the term 'Small Solar System Bodies'. So we have 8 Planets and numerous large planetesimals. Pluto never finished accreting because of the neighborhood that it was born into. If you don't like the term 'dwarf planet' then call them large asteroids, large comets, or large planetesimals. 'Dwarf Planets' (compound noun), by definition, are no longer called Planets. What ever scientific process is used to call Pluto 'anything' will also likely apply to Ceres. One could make a case that Vesta is a 'dwarf planet' remnant because Vesta accreted large enough to become a protoplanet as Vesta did differentiate (heavier elements sank to the center; while lighter elements rose to the surface.) (Click here to see Vesta differentiated) And that's the problem. in the 20th C. they had to wisdom to realize

robnissen · Sep 29, 2006

"I reallly wonder what they'll do when those really, really large KBO's get found, as the distribution curves show are likely to exist out beyound the planets, Neptune and Pluto? Then they will be in a quandary." NO, they won't. As I and others have stated previously, if it orbits the sun (or another star) and it is at least the size of Mercury it is a planet. If it is smaller than Mercury, its not a planet. And yes I understand that is an arbitrary limit, but using the size of Pluto is also an arbitrary limit. But the difference is, as has been stated numerous times, Pluto was only called a planet by MISTAKE, namely that it was thought to be much larger than Mercury. The IAU has now fixed that mistake, as the mistake regarding Ceres and some other asteroids were also fixed. I fail to see what the big fricken deal is.

Pluto defines a Planet as being a Planet!

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