Dwarves and the Pluto Controversy

[sparkyjim]

I think everyone here must be well aware of the controversy that surrounded the IAU's decision to create the classification of Dwarf Planet, demote Pluto to this and then state that the objects so classed were not actually planets!<br /><br />What a bloody mess, intelligent people and yet they created a total shambles out of a fiasco.<br /><br />I wonder what the views are of those here?<br /><br />My personal view is that it was right for Pluto to lose the Major Planet status, and whilst I am comfortable with the term Dwarf Planet, the classification is messy. A Dwarf Planet should still be a planet..just a small one. Afterall a Dwarf human is no less human that you or I..we would not reclassify them as seperate from us.<br /><br />I think the IAU missed an opportunity to create a classification system for planetary system objects overall, not just planets. For my money I do not class the Moon as a satellite of Earth, but rather I class them as a double planet, and thus the Moon should have been elevated to, albeit, dwarf planet status.<br /><br />What do you all think about this...should there be an overall classification system for objects that orbit stars..afterall we know of far more worlds around other stars now than our own..thus the simple system we have will not likely surfice..<br /><br />Jim

 

[alokmohan]

In our solar system,there are six bodies larger than pluto.Moon,Io,europa,ganymede callisto.triton.They should be called dwarf planets.

 

[sparkyjim]

I don't think size alone can be used as a criteria for Dwarf Planet status. Io, Europa, Callisto, Ganymede, Titan and Triton are most certainly satellites of their parent world. The mass differance between them is very large indeed and the common centre of gravity is fixed and to all intents and purposes in the centre of the parent world.<br /><br />Charon was classed as a Dwarf Planet due to the common centre of the Pluto / Charon system laying between the two in space and it has officially be classed as a double dwarf planet.<br /><br />I class the Moon as a Dwarf planet as both Earth and the The Moon orbit a common centre of gravity that is nowhere near the centre of Earth, it is a mere 2200 miles beneath our feet. Further, the barycentre point is migrating outward as the Moon loses orbital energy and moves away from Earth at about 3cm per century, or 3m per millenia. In the not too distant future the centre of the Earth / Moon system will be on the surface of the planet...which could be interesting!!

 

[MeteorWayne]

Back when the controvery erupted we had many long discussions on the subject.<br /><br />Pluto is still a planet, just a dwarf one.<br />I don't mich like the term dwarf, but there are precedents in the naming of obsjects (dwarf stars, dwarf galaxies, etc) so I guess it's OK.<br /><br />One good thing that came out of it was elevation the status of Ceres, which is clearly the ruler of the Asteroid belt, containing 30% of the mass of the belt.<br /><br />In fact, the case can be made that Pluto and Charon are a double dwarf planet, since the barycenter lies between them.<br />In my opinion, this does not apply to the earth-moon system, since the barycenter does lie beneath earth's surface. <br /><br />Also our Moon is a satellite, as are the other objects larger than Ceres, Pluto, and Eris. To me way of seeing things, that places them in a separate class :<br />natural objects orbiting planets. In my mind, that makes Trition, Titan and all the others moons.<br /><br />As far as extending definitions to other stellar systems, I believe it's too early to do that. We have just begun to scratch the surface of what kind of "exoplanets" are out there. For now, the unofficial term exoplanet works just fine.<br /><br />In a decade or two, when we have a much better sense of the types of objects and orbits there are, we can see if further refinement is needed.<br /><br />{ka-ching, ka-ching} <br /><br />Wayne deposits his 2 cents. <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[docm]

IMO;<br /><br /> a 'planet' is a celestial body orbiting a star or stellar remnant that is massive enough to be rounded by its own gravity, is not the natural satellite of a larger body and is not massive enough to cause thermonuclear fusion in its core.<br /><br />A 'moon' should simply be a natural satellite smaller than its partner.<br /><br />The clearing of planetesimal's business is stupid since using that criteria Jupiter doesn't qualify because of the Trojan & Greek asteroids.<br /><br />The barycenter shouldn't matter either since, as noted above, some day the Earth/Moon barycenter will lie outside Earth's surface.<br /><br />"Double Planet"? Interesting concept, but then you start a fight over where the cutoff is between a 'moon' and the smaller partners size; 50% the diameter of the larger partner? 75%? 80%? What if it's 79.9%? I'd rather keep it simple; the smaller partner is a 'moon', period.<br /><br />Therefore; Ceres, Pluto and Eris should be full planets and Charon, Titan, Triton etc. should remain moons. <br /><br />2005 FY9 "EasterBunny", Sedna, Quaoar etc. should be determined later as their shapes become clear. <div class="Discussion_UserSignature"> </div>

 

[vandivx]

docm makes sense, I see it the same way, it is most reasonable way IMO<br /><br />vanDivX <div class="Discussion_UserSignature"> </div>

 

[alokmohan]

William Shakespeare said ,what is in a name?Shkespere gulped names of all moon of Uranus.What logic.So nothing is in a name.

 

[h2ouniverse]

And everything is in a name.<br />There is a saying in French "De la confusion des mots nait la confusion des idées" (from confusion of words arises the confusion of ideas).<br />Look at Ceres. Considered a planet with a sign and so on in the first half of 19th century, then a boring piece of matter until just a few years.<br />Now we realize it is differentiated. Probably hosts very interesting chemistry on surface, with clays... Then people decide to model it thermally and discover its core should still be warm, about 400K.<br />And may be still a liquid water layer at core/ice interface. And cracks. and so on...<br />Names determine prejudices. Prejudices determine attention. Attention leads to curiosity and motivation and to put more and more energy an dtime in studying something. Even the most objective scientific mind is a human mind, biased in some way by the wording.<br /><br />By calling Ceres an asteroid, we had missed its true nature (differentiated body). If it had been called a planet, or mesoplanet, or dwarf planet, Hubble would have imaged it and discovered its hydrostatic equilibirum far sooner than beg 2004!!!!<br /><br /><br />Regards.<br /><br />