The Case For Pluto

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nas76
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The Case For Pluto

Post by nas76 »

I received this book (title in subject line) at Christmas and I can very much recommend this quite enjoyable read.

The author, Alan Boyle, mentions in the forward that like a number of astonomers he too agreed that Pluto should be relegated without giving it much thought. It was after sitting down and discussing it at length that he realised what a mistake had been made.

The book starts off by retelling the history of the discovery of the planets beyond Saturn and also the asteroids. Of course Pluto is the primary subject and this section goes on to explain why observations from about 1950 onwards led us to believe that it was a lot smaller than originally predicted, along with how the debate regarding its status hotted up shortly after the discovery of Charon.

The book is very critical about the IAU and way the debate took place back in 2006, particularly how it presented the "new definition" of a planet that eventually saw it reclassified as a Dwarf-Planet. It gives an insight to how the process was cobbled together not long before the 26th IAU General Assembly, and the way that Pluto was voted on.

The author concludes that it is impossible now to not describe a set of planets without placing an adjective in front of it. He argues early on, does the name "Dwarf-Planet" not have the word planet in it?

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Although I did read it in a short amount of time, as I didn't go to work for 2 weeks until today, so I may not have absorbed everything. However I can say that the book was a real eye-opener about the process, the history of the discovery of trans-Neptunian objects and the arguments surrounding Pluto. It also changed my view about Pluto, I previously viewed it as the oddball in the list of 9, much like the author did, and unjustifiably I was quite happy to say that it didn't count any more and was just a part of the Kuiper belt. The book thrust my opinion of the majesty of the Kuiper belt, and in my view now I would be quite happy to call Pluto a Kuiper-Belt planet, along with Makemake, Eris et al.

This is the first time I've ever reviewed a book before so I apologise if it comes across as a load of rambling! Even so, I do recommend it as some good bedtime reading.

The Case For Pluto is published by Wiley.


Regards,

Neil
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mike a feist
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Post by mike a feist »

This is no criiticism of the book review but I really cannot face going over all this material yet again. I do not really care about Pluto, Makemake, Eris or any of the asteroidal-size chunks that I cannot see from my garden. Mercury to Neptune, will do me as the 8 (Classical Planets + satellites + asteroids (perhaps better called planetoids)+ comets. Although of course some satellites were probably once comets or asteroids (planetoids) and some comets seem to be reactivated asteroids and some asteroids(planetoids) may be dead comets. etc etc. So pretty hopeless to nail down the definitions scientifically anyway even of these smalller bits.

maf
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Post by Cliff »

Dear Neil Nas76
I half agree with both Mike and yourself on this one.
But whatever I personally think will make little difference to what the IAU decide (having read elsewhere that what's been decided to date isn't likely the end of the story ?).
My own feeling is whatever the IAU decide is not likely to affect Pluto itself very much, excepting for the possibility of the instigation of more Pluto probes. Whether, Pluto will like to get more visits I do not know.
I wonder if Pluto was pleased with Clyde Tombaugh for discovering it, and what it thinks about being called Pluto.
I suppose it's like someone recently said about a whiteman discovering what they called Victoria Falls although local Africans had seen it before for donkeys years.
From what I think I read somewhere I gather most of the delegates had gone home when the IAU got round to considering Pluto (?).
Best wishes from Cliff
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Post by joe »

Sounds like a good read Neil. Thanks.
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Mogget
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Post by Mogget »

For what it's worth, I think that the IAU were correct to remove Pluto's status as a major planet. It is much more closely matched to the Kuiper Belt objects, both in size and orbital characteristics (several other objects in the belt also share a 2:3 orbital resonance with Neptune).
nas76
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Post by nas76 »

Cliff wrote:From what I think I read somewhere I gather most of the delegates had gone home when the IAU got round to considering Pluto (?)
Yes that is true according to the book, also at the time some members tried to cobble together a sub-clause and the whole thing got over complicated.
Mogget wrote:For what it's worth, I think that the IAU were correct to remove Pluto's status as a major planet. It is much more closely matched to the Kuiper Belt objects, both in size and orbital characteristics (several other objects in the belt also share a 2:3 orbital resonance with Neptune).
Yes I agree that it should have had its status downgraded, however the book also points out that Pluto, among other objects, cross the path of Neptune. Therefore Neptune could not be a planet because it did not comply with one of the three parts their new definition of planet, namely that Neptune had not cleared its orbital path. This is one of the reasons why the argument for downgrading Pluto was flawed.

Finally as Cliff implied, whatever we call it, describe it or crash into it - it doesn't stop Pluto from being Pluto.

Neil
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Post by Deimos »

To my mind the classifications of objects/things is there to be useful, often describing mechanisms, limitations, function or something about what is being classified. A biological species defines a lot of attributes about that group of organisms and is not just a "name". Similarly, a Type Ia supernova is not just a name or just a classification but describes mechanisms and characteristics and people know a fair amount about the object from its classification.

Classifications is thus important but should be useful. I can appreciate that classifying bodies in the Solar System is useful. You have those with moons, those with adequate gravity to be spherical, those in orbits close to circular, etc. I am neither for or against Pluto being a "planet" but still cannot appreciate the line the IAU drew. What I think made things worse for the scientific community was the way the IAU (or rather "the campaigners for change" in the IAU) behaved. Having the vote at a time when many had left the conference, the behind the scenes campaigning all did not help the public perception of the scientific community.

Were a change of classification justified on grounds of usefulness then the proposal for change should have been able to stand in its own right without the need for underhand political style campaigning. It should have ben a straightforward decision. Of course there would still have been people agreeing and disagreeing but let that debate happen in open at the conference.

But then maybe the "underhand tactics" used by those seeking change was all created by the press - which is just as bad. Professional astronomers are often spending public money - money people have worked hard for to have their government take and spend on things they might not see as useful. When the public see petty political behaviour presented in the popular press it does not make them feel good about how their money is being spent. Justify the change on the basis of usefulness and have open "above board" discussions and there is no issue. Whilst the change did get Astronomy into the limelight briefly it was not really there for positive reasons so was no real help to the discipline.

Ian
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Post by Mogget »

Therefore Neptune could not be a planet because it did not comply with one of the three parts their new definition of planet, namely that Neptune had not cleared its orbital path. This is one of the reasons why the argument for downgrading Pluto was flawed.
I think that the term "clearing its orbital path" is misunderstood. This refers to objects that are in very similar orbits. In other words, has Neptune effectively cleared its own orbit of all debris that is not locked into stable orbital resonances? The answer is yes, because slight differences in the orbital period would eventually lead to objects of this type getting close to Neptune, and the planet's gravity would kick them out of the region. Pluto is in a stable 2:3 orbital resonance with Neptune, so the two bodies never get anywhere near each other. In fact, Pluto can get closer to Uranus than it can to Neptune!

The Trojan asteroids are also a good example of objects that have similar orbits to the giant planets, but they are only there because of stable Sun-planet-asteroid resonances.
Sabreman64
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Post by Sabreman64 »

Regardless of the IAU decision, I still consider Pluto to be a planet.

Simon
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Post by Astrocomet »

Sabreman64 wrote:Regardless of the IAU decision, I still consider Pluto to be a planet.

Simon
Well we all should be made more aware if this is a planet or not when this arrives 5 years from now in 2015:

http://www.nasa.gov/mission_pages/newhorizons/main/

And this:

http://pluto.jhuapl.edu/mission/whereis_nh.php
Colin James Watling
--
Astronomer and head of the Comet section for LYRA (Lowestoft and Great Yarmouth Regional Astronomers) also head of K.A.G (Kessingland Astronomy Group) and Navigator (Astrogator) of the Stars (Fieldwork)
https://sites.google.com/site/lyrasociety/
http://www.lyrandgyastronomers.blogspot.com/
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Post by Mogget »

Regardless of the IAU decision, I still consider Pluto to be a planet.
In that case, you will need to add Eris to your list.
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