Pluto Perspectives, Part 1- Intro and Size

MeteorWayne · Sep 5, 2006

In my next several posts here, I will try, in my own way to explain why I think pluto belongs in a different class then the "big" eight planets. I'll discuss issues one at a time, with plenty of time for comment, then wrap it up at the end, whenever or wherever that is. <img src="/images/icons/rolleyes.gif" /> No one issue makes the case, rather it is the totality that clarifies things. I could do one big long one, but that's too much to wade through, and besides, it's clearer to discuss them individually. No matter what, Pluto resides at the border between "planets" and what I'd rather call "minor planets" than dwarf planets. The exact nomenclature is not important. What will (hopefully) become clear is why pluto doesn't quite make the cut, IMO. OK, first subject- size. I have listed the top 27 or so largest heliocentric objects in the solar system. As far as I know. At this time. By my own definition, I have not considered satellites. If it orbits a planet, it's a satellite, even if it's big. It's my presentation, so that's my choice <img src="/images/icons/smile.gif" /> There are other valid points of view. This is only for objects that orbit the sun in "independent" orbits. As for the Pluto/Charon "binary object" discussion, we'll cover that later. Please bear with me. The chart below lists those objects in decreasing diameter, in kilometers. Thanks to Kevin Heider in the "Should Pluto be excluded from Solar System models now?" thread for inspiring my examination. For the Big Eight, sizes are pretty well established. Pluto's size is well known due to occultations. All other sizes are estimates of varying degrees of accuracy. When there are differing estimates I have used the smaller ones, to give ol' Pluto the benefit of the doubt. Also, be aware that estimates can change, new objects are discovered daily, and I may have made a boo-boo here and there despite my best efforts. The first column is <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 5, 2006

Pluto defines a Planet as being a Planet! I thought I would help your post along you will need it! “No matter what, Pluto resides at the border between "planets" and what I'd rather call "minor planets" than dwarf planets. The exact nomenclature is not important. What will (hopefully) become clear is why pluto doesn't quite make the cut, IMO” Thank you for making my point and with everything you have shown here you have mistakenly selected Pluto for the cutoff of where a “Dwarf Planet” ends and a “Planet” begins! If Pluto doesn’t “quite” make the cut then you have become your biggest challenger as to why Pluto should make the cut! What was held in Prague was a General Assembly of the International Astronomical Union (IAU) and, the intent of these General Assemblies are to decide on specific arbitrary definitions that allow astronomers to talk to one another across language barriers enabling the world’s various science communities to interpret each others data. One very specific point stands out and that is the word “arbitrary” and, although I completely understand the need to arbitrarily categorizes what we see to break up the job of assessment. I think that Pluto has stood the test of time and technology, if there is to be an arbitrary cut off of were a “Dwarf Planet” ends and a “Planet” begins it should be Pluto! <div class="Discussion_UserSignature"> </div>

MeteorWayne · Sep 5, 2006

Don't judge until you read parts 2 thru 5? Besides, I thought I made the point clear. Pluto is but one of many similarly sized objects. Mercury is twice the size of Pluto, Pluto is not even 1 1/2 the size of anything smaller. It is one of the family of smaller objects. All the others are unique in their own way, as will be shown in the parts to come. Pluto is not. I did not use the word arbitrary. The data spoke for itself. Size alone is not conclusive however. Working on Part 2 now. <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 5, 2006

The word “arbitrary" is how the IAU demoted Pluto and although the gentleman named below prescribes to your beliefs I think he basically says what you are saying so, I once again submit that Pluto should remain a Planet. The IAU as described by the individual at this link “Guy J. Consolmagno” is a member of the American Astronomical Society, Division for Planetary Science. He explains how the IAU is broken into various committees. The committee responsible for Pluto’s demotion was referred to as the IAU’s Division III (the planetary scientist’s corner of the IAU). Here is how he describes what went on in Prague: ----------------------------------------------------------------------- General Assemblies are different from typical scientific congresses. Rather than being focused exclusively on presenting scientific results, the main point is to decide on all the arbitrary but necessary definitions that let us talk to each other and understand each other's data. For example, were worrying about tweaking the definition of latitude and longitude on the Moon to match the expected precision of the coming generation of lunar spacecraft from India, China, Japan, and the US. Likewise, defining what is a planet is both arbitrary and necessary. How do we name the newly discovered objects out beyond Pluto, that rival Pluto in size? (The rules, and the committees, for planets are different than those for comets and asteroids.) Which committee keeps track of their orbits, and assigns names to their surface features? What definition works for planets around other stars? ----------------------------------------------------------------------- One very specific point stands out and that is the word “arbitrary” and, although I completely understand the need to arbitrarily categorizes what we can see and don’t understand to break up the job of assessment. I think that Pluto has stood the test of time and technology, if <div class="Discussion_UserSignature"> </div>

MeteorWayne · Sep 5, 2006

Hang in there Jake. The whole point of what I am doing is to show that while it may seem arbitrary when you look at individual items, when you look at all the factors, it is not. MW <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>

silylene old · Sep 5, 2006

I wouldn't have called Uranus and Neptune "ice giants". Both planets are heavily dominated by a very thick 83:15:2 H2/He/CH4 atmosphere (74:25:1 for Neptune), have rings, have a myriad of moons, and are thought to have an icy core topped with a thick mantle of liquid H2 (no real surface). Both have a strong magnetic field. Jupiter and Saturn are also dominated by a very thick atmosphere, respectively 86:14 and 95:5 H2:Hewith about 0.1% CH4, plus other gases. Both planets are thought to have a thick mantle of liquid H2 surrounding a core (icy core with a metallic H2 outer core) (no real surface). Both have magnetic fields, with Jupiter's being very strong. Both have a ring systtem and a myriad of moons. I don't understand why Jupiter and Saturn are "gas giants", and Uranus and Neptune are "ice giants". What ice do you refer to? hopefully you have noticed in my first two paragraphs I showed that there were many more similarities than differences among planets 5-8. I would've said that Jupiter and Saturn are moderate sized gas giants, and Uranus and Neptune are smaller sized gas giants. Why "moderate sized"? Well, we know that there are quite a few much larger extra-solar gas giants, 2x to 10x Jupiter's mass. These extrasolar planets are "large gas giants" (It would be awkward to call them "giant gas giants"!). If Titan were a planet and not a moon, perhaps it could be called a "tiny gas giant". Perhaps not, since it has a real surface.... <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>

search · Sep 5, 2006

Hello Meteorwayne I know you are doinfg a personal insite on Pluto. And a quite interesting one but maybe people should get the IAU definition from the Resolutions adopted in the Prague conference which is now available online. having the official definitions in mind makes it easier: http://www.iau.org/Resolutions_at_GA-XXVI.340.0.html the real juice: http://www.iau.org/fileadmin/content/pdfs/Resolution_GA26-5-6_.pdf

MeteorWayne · Sep 5, 2006

OK, but the official definition has been beaten to death. I'm trying to get beyond that and make the case as to why Pluto doesn't belong with the other 8. For reference, though, here are the resolutions RESOLUTION 5A The IAU therefore resolves that "planets" and other bodies in our Solar System be defined into three distinct categories in the following way: (1) A "planet"(1) is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighbourhood around its orbit. (2) A "dwarf planet" is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape(2) , (c) has not cleared the neighbourhood around its orbit, and (d) is not a satellite. (3) All other objects(3) except satellites orbiting the Sun shall be referred to collectively as "Small Solar-System Bodies". -------------------------------------------------------------------------------- 1) The eight planets are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. 2) An IAU process will be established to assign borderline objects into either dwarf planet and other categories. 3) These currently include most of the Solar System asteroids, most Trans-Neptunian Objects (TNOs), comets, and other small bodies. -------------------------------------------------------------------------------- IAU Resolution: Pluto RESOLUTION 6A The IAU further resolves: Pluto is a "dwarf planet" by the above definition and is recognized as the prototype of a new category of trans-Neptunian objects.1 <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>

search · Sep 5, 2006

Maybe I missed some step of the procedure but; Could you be more specific on "the official definition has been beaten to death"? The resolution was adopted. It is no longer a proposal In any case there is now 8 planets and that seems to be your goal proposal IV. RESOLUTIONS OF THE UNION Traditionally, the decisions and recommendations of the Union on scientific and organizational matters of general and significant importance are expressed in the Resolutions of the General Assembly. In order for such Resolutions to carry appropriate weight in the international community, they should address astronomical matters of significant impact on the international society, or matters of international policy of significant importance for the international astronomical community as a whole. Resolutions should be adopted by the General Assembly only after thorough preparation by the relevant bodies of the Union. The proposed resolution text should be essentially complete before the beginning of the General Assembly, to allow Individual and National Members time to study them before the vote by the General Assembly. The following procedures have been designed to accomplish this: 12. Proposals for Resolutions to be adopted by the General Assembly may be submitted by a National Member, by the Executive Committee, a Division, a Commission or a Working Group. They should address specific issues of the nature described above, define the objectives to be achieved, and describe the action(s) to be taken by the Officers, Executive Committee, or Divisions to achieve these objectives. 13. Resolutions proposed for vote by the General Assembly fall in two categories: 13.a. resolutions with implications for the budget of the Union; or 13.b. resolutions without financial implications. Proposals for Resolutions should be submitted on standard forms appropriate for each type, which are available fro

MeteorWayne · Sep 5, 2006

The beating to death I was referring to was in the dozen or so threads in SDC. Maybe two dozen <img src="/images/icons/smile.gif" /> I am explaining the rationalization for why I feel as I do, in a logical manner. Thanx for the IAU rules you posted, I'll read them now. It will help me understand whether what they did followed the rules. Again, that isn't necessarily the point of my posts, but could be related once I read them Thanks again. Wayne <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>

MeteorWayne · Sep 5, 2006

silyene, First, All the Giants are planets. No dispute there, methinks. One reason to separate them is due to the huge difference in size and masses. I'll grab those numbers. I have to find the reference I used to come up with the idea of Gas and Ice Giants, don't have in on hand at the moment. I've been writing parts 1 to 5, so some material is not on the top of the pile. Thanks for your comments. That's really what I'm trying to do- spark conversation in a fruitful way, rather than the "Well, Pluto's a Planet because it's been forever and I don't care what anyone says", or Pluto's not a planet because I feel that way". I'm trying to document my reasoning, in detail, for my choice on the issue. I hadn't even intended to differentiate between Jupiter/Saturn and Uranus/Neptune, until I plotted the size and masses in my excel spreadsheets...at that point it was too obvious to ignore IMHO. Like I said, I have a real reason for the distinction...IIRC it comes from the May 11 Nature article on Triton's capture. I will get back to you on that. Thanks for a thoughtful reply. Wayne <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>

search · Sep 5, 2006

I think the main problem was when in middle august the draft proposal was leacked and typical media frenzy created this idea of 12 planets and that became quickly attached everybodys mind. But the end result not being so spectacular was not even mentioned. I think we should be doing a thread on the increasingly poor media performance when it comes to scientific subjects.

jaxtraw · Sep 5, 2006

Meteorwayne: I don't think most people are disagreeing with you that there are many different classes of object in the solar system, or that Jupiter and Pluto are different types of object. The objection as I see it is the hierarchical structure. Let's call Pluto and Xena Dwarf Planets (or I'd prefer Ice Dwarfs personally, because it's kind of mythological sounding <img src="/images/icons/smile.gif" /> ) but that should be a category, in a hierarchical sense, alongside Gas Giant and Terrestrial- all subclasses of the general "planet" which should just mean "non-luminous round thing", basically. IMHO, of course <img src="/images/icons/smile.gif" /> Just as Galileo faced the wrath of the Inquisition, I likewise am prepared to face looking slightly silly on an internet discussion board, steadfast in my assertion that no rational class of objects would contain objects so dissimilar as Jupiter and Mercury, unless it's a very broad class that should contain Pluto-like worlds also.

wonky · Sep 5, 2006

Wayne, where are the next parts? I've said on other threads that I think the "Pluto has always been a planet so it should stay that way" arguement holds no water. In antiquity--for literally THOUSANDS of years--the sun and moon were considered planets. The Gallilean satellites of Jupter were first called planets, as were the first 4 asteroids to be discovered (and they remained so for half a century.) The fact of the matter is that in general, people just don't like change. What else needs to be said? What we really need is an improved definition of both "planet" and "dwarf planet." And to all the Pluto fans out there, rest assured. Pluto will not be removed from all the astronomy books. It's going to be in there along with all the other dwarf planets. The only real difference is that it will have a different chapter heading.

tony873004 · Sep 6, 2006

Xena, Santa, 2005 FY9, Sedna, Quaoar, Ceres, Vesta, Pallas, and possibly others on your Plutino list are not Plutinos. They are not in a 2:3 resonance with Neptune.

MeteorWayne · Sep 6, 2006

Some good points there, jaxtraw. <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>

MeteorWayne · Sep 6, 2006

They are not on the list as plutinos. The only 4 plutinos listed are Ixion, Pluto, Orcus, and Huya Check the class designation after the names, Plutinos are labeled PL <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>

MeteorWayne · Sep 6, 2006

I'm working on the other parts. Time is a bit limited right now as I am working with a contractor to rebuild my back patio, so I kind of have to work around his schedule and a bit of sleep here and there <img src="/images/icons/smile.gif" /> Wayne <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>

tony873004 · Sep 6, 2006

Sorry, I though the horizontal lines were dividing objects up into the sub-groups you defined earlier. Glad to hear you didn't consider Ceres a Plutino <img src="/images/icons/smile.gif" />

MeteorWayne · Sep 6, 2006

No problem, I went back and looked just to be sure. That last line was seperator for the last jump of 2X in mass between objects. I'll probably go back and reformat the list to look more like part 3 with the ......s spacing the columns out for easier viewing. <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>

wonky · Sep 6, 2006

How is the reclassification of Pluto going to cost society 10's of millions of dollars??? They're eventually gonna have to come out with new editions of textbooks, anyway.

MeteorWayne · Oct 2, 2006

{bump} Coming soon..latest data. Wayne <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>

MeteorWayne · Oct 2, 2006

Here is a revised listing of the largest objects in the Solar System (other than the Sun, which is 99.87% of the Solar System It includes those larger than 475 km in diameter, to limit it to less than 50. It only includes objects in a solar orbit, satellites are excluded. Data is current as of September 14, 2006, with sizes beyond Pluto from the latest MPC data as of Aug 28th. We have accurate diameter measurements for the terrestrial planets, and Pluto. The Gas Giants (pGG), and the Gas Mediums (pBG) are the diameters to 1 bar pressure. These are from the RASC 2002 Observers Handbook. The size for everything beyond Pluto are ESTIMATES, making a number of assumptions. They are not precise, but there are enough of them to get a feel for the statistics. They probably are not off by more than +/- 50%. The mass for everything beyond Pluto is estimated using the density of Pluto (since nothing is known for more distant objects, and most asteroids,) and is displayed here compared to earth. Again, these are estimates, but should not be off by much more than a factor of 2. Name= Common name of object. Disc Desig= Discovery designation using the current system. Where there is none, I have included Planet or Asteroid to make the post easier to read. You have no idea how difficult that is. It's the reason for all the dots in this post, but is much easier to read than the first Pluto Perspectives, Part 1. MPC # = Minor Planet Center small solar system object number, up to and including Pluto, # 134340. Again, for objects without one, I have written something here for readability. 00000 means none has been assigned. Class= General type of Object. The first four are just my attempt to categorize the planets. When you look at the data, it is clear that there are 4 two member groupings, or 2 four member groupings. They don't mean too much, other than my attempt to group (categorize) them. By the IAU definiti <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>

kheider · Oct 2, 2006

Wayne; Thank you for the great post! You have made a great table and I am sure that there was a lot of work involved. My only immediate reaction is that this very long list of potential 'dwarf planets' (protoplanets?) shows why Pluto will never be listed as a Major Planet again. (This is not to say that Pluto will never be redefined as a Planet.) I do find it interesting that some theories suggest that little Mercury use to be a Chthonian Gas Giant early in the Solar Systems history. This theory does allow comparisions between Mercury and Jupiter. Links: Chthonian Planets HD 209458b (Osiris) -- Kevin Heider

MeteorWayne · Oct 2, 2006

Keviin, thanks for that link. Although I knew of the concept, I had no idea of the name for such objects, nor could I even spell it now, even if I was looking at the spelling! <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>

Pluto Perspectives, Part 1- Intro and Size

MeteorWayne

Guest

jakethesnake

Guest

MeteorWayne

Guest

jakethesnake

Guest

MeteorWayne

Guest

silylene old

Guest

search

Guest

MeteorWayne

Guest

search

Guest

MeteorWayne

Guest

MeteorWayne

Guest

search

Guest

jaxtraw

Guest

wonky

Guest

tony873004

Guest

MeteorWayne

Guest

MeteorWayne

Guest

MeteorWayne

Guest

tony873004

Guest

MeteorWayne

Guest

wonky

Guest

MeteorWayne

Guest

MeteorWayne

Guest

kheider

Guest

MeteorWayne

Guest

Similar threads

TRENDING THREADS

Latest posts

Moderators online

Share this page