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Date: 18 Aug 2006 01:46:20
From: mirceaar
Subject: 2006 IAU 12 planets resolution petition
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At
http://www.petitiononline.com/9planets/petition.html
you will find a petition that considers that the current resolution of
IAU regarding the definition of a planet is currently innapropriate.
Although it does not provide another definition for planet - which is
rather a difficult one - it considers that the stated definition will
create confusion more than anything else, not necessarily within the
scientific community, but with people in general. The petition text is
written by an amateur astronomer, so don't expect much scientific
eloquence.
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Date: 18 Aug 2006 09:42:38
From: mirceaar
Subject: Re: 2006 IAU 12 planets resolution petition
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I was afraid of such a reaction, but had too little time to put it
together, and to have proposed a draft and having agreed to one final
versiom, together with other people more authorised to have a word in
it, that would have taken too long.
And those people I know and were capable of putting together a more
pertinent statement than I am, were at the time, let's say, reluctant.
Now they're sorry they didn't get involved then.
Greg Crinklaw wrote:
>
> Nonsense. The astronomical community is actually very small. What
> people think *does* count.
>
> But this petition is very poorly worded (delving into Bode's law of all
> things). I would have loved to have signed it, but for that.
>
> Greg
>
> --
> Greg Crinklaw
> Astronomical Software Developer
> Cloudcroft, New Mexico, USA (33N, 106W, 2700m)
>
> SkyTools: http://www.skyhound.com/cs.html
> Observing: http://www.skyhound.com/sh/skyhound.html
> Comets: http://www.skyhound.com/sh/comets.html
>
> To reply take out your eye
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Date: 18 Aug 2006 09:39:19
From: Eric Chomko
Subject: Re: Ceres - The Fifth Planet From The Sun
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Landy wrote:
> Eric Chomko wrote:
>
> > Thomas Lee Elifritz wrote:
> > > I guess I'm ok with this. We get a fifth planet, representing asteroids,
> > > the Sun is the Origin (0), and everything else 10 and above is a pluton.
> > > Then there are the plutinos, and apparantly a wholelotta pluterinos.
> > >
> > > Jeez, there's a lot of purple ice out there.
> >
> > Which used to be purple rain until Prince lost his ability to make
> > music and perform.
> Um, can you lose something you never had in the first place?
No, his early stuff was good and when he initially performed all was
new. Now, he's the same old, same old and his music is inferior, IMO.
Eric
> cheers
> Bill
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Date: 18 Aug 2006 05:57:28
From: mirceaar
Subject: Re: 2006 IAU 12 planets resolution petition
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Of course it not will deter them, but it's better than nothing.
Stan Jensen a scris:
> Stupid.
>
> Give it up. No one is going to deter the IAU from whatever they are
> going to do.
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Date: 18 Aug 2006 08:11:46
From: Stan Jensen
Subject: Re: 2006 IAU 12 planets resolution petition
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Stupid.
Give it up. No one is going to deter the IAU from whatever they are
going to do.
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Date: 18 Aug 2006 10:19:28
From: Greg Crinklaw
Subject: Re: 2006 IAU 12 planets resolution petition
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Stan Jensen wrote:
> Stupid.
>
> Give it up. No one is going to deter the IAU from whatever they are
> going to do.
Nonsense. The astronomical community is actually very small. What
people think *does* count.
But this petition is very poorly worded (delving into Bode's law of all
things). I would have loved to have signed it, but for that.
Greg
--
Greg Crinklaw
Astronomical Software Developer
Cloudcroft, New Mexico, USA (33N, 106W, 2700m)
SkyTools: http://www.skyhound.com/cs.html
Observing: http://www.skyhound.com/sh/skyhound.html
Comets: http://www.skyhound.com/sh/comets.html
To reply take out your eye
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Date: 18 Aug 2006 17:42:53
From: SkySea
Subject: Re: 2006 IAU 12 planets resolution petition
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Okay, so...
If the amateur astronomy community really has an ear in the IAU, "we"
(amateur astronomers) could do something more productive than say a
negative petition.
We could come up with a "better" nomenclature.
As a practical exercise, let's see what happens when we attempt to
define what a planet is. Let's see if we can come up with some
definition that shows the IAU is a bunch of clueles, pretentious, good
'ol boy geezers.
We've discussed that "roundness" is arbirtary, that the bodies'
evolutions shouldn't be ignored, that double-planets are silly, that
"plutons" can't be planets, except maybe for Pluto itself (but that's
not a planet because it's really a KBO), that fusion defines a star,
but when the star stops fusing it becomes a corpse (a new type of
object?), that we're not sure yet whether the barycenter of a
planetary system should play a role or not, that definitions should be
able to change with technology, (or not)...
I'll take a stab at a definition, and let the world rip it to shreds
and come up with something better:
"A planet is a aggregate of solid materials constituting a primary
mass (in the case of systems) shaped to spherical by gravity
overcoming hydrostatic forces (in the absence of any rotational
effects), in an orbit around a star (fusing or remnant) or within a
star system."
Alas, Pluto would still be a planet. But Charon wouldn't be. We'd pick
up Ceres and UB 313.
Go ahead boys.... have fun! Let's see what we GREAT minds can agree
upon and wow the professionals with.
>Greg Crinklaw <theskyhoundyoureye@yahoo.com> wrote:
>Nonsense. The astronomical community is actually very small. What
>people think *does* count.
=============
- Dale Gombert (SkySea at aol.com)
122.38W, 47.58N, W. Seattle, WA
http://flavorj.com/~skysea
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Date: 18 Aug 2006 11:27:39
From: Brian Tung
Subject: Re: 2006 IAU 12 planets resolution petition
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SkySea wrote:
> If the amateur astronomy community really has an ear in the IAU, "we"
> (amateur astronomers) could do something more productive than say a
> negative petition.
>
> We could come up with a "better" nomenclature.
Here's one I came up with, just playing around. I don't think it's any
better than what the IAU is kicking in the air, but I'm not sure it's
any worse, either:
How do planets form? Once they get large enough, by accretion. If a
body isn't sufficiently large, then an incoming piece of debris doesn't
accrete, it just bounces off. How massive does a body have to be before
an incoming piece of, say, water ice at the triple point melts to become
water at the triple point, so that it just sits there in a puzzle (and
possibly refreezes later on)?
The heat of fusion of water is about 335 kJ/kg. In order for impact to
deliver that much energy to one kg, the incoming mass must be travelling
at about 820 m/s. So an object with an escape velocity of 820 m/s
should just be able to melt an incoming piece of water ice.
Interestingly...
Pluto's escape velocity is 1220 m/s
Ceres's escape velocity is 450 m/s
Charon's escape velocity is 660 m/s
The mass of 2003 UB313 isn't currently known, but assuming it's at least
half that of Pluto, it would also have an escape velocity greater than
820 m/s.
--
Brian Tung <brian@isi.edu >
The Astronomy Corner at http://astro.isi.edu/
Unofficial C5+ Home Page at http://astro.isi.edu/c5plus/
The PleiadAtlas Home Page at http://astro.isi.edu/pleiadatlas/
My Own Personal FAQ (SAA) at http://astro.isi.edu/reference/faq.html
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Date: 18 Aug 2006 17:52:44
From: SkySea
Subject: Re: 2006 IAU 12 planets resolution petition
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P.S. ...
The real exercise is to demonstrate that:
1) There can never be a definition that will satisfy everyone's
concept of what a planet is, and
2) Some folks are going to criticize anything just because they can,
and it's fun to show that they know better.
3) Although lots of discussion will go on, very few, if anyone, will
actually offer up their own version of a formal definition, because of
#1 and #2 above.
=============
- Dale Gombert (SkySea at aol.com)
122.38W, 47.58N, W. Seattle, WA
http://flavorj.com/~skysea
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Date: 18 Aug 2006 11:06:59
From:
Subject: Re: The IAU Draft Definition of 'Planet' and 'Plutons'
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This is a bad definition, and the reason they got it wrong is that used
the wrong set of criteria for a "good definition".
Looking at how they defend their draft, I see that they were looking
for a definition that
1. was "not arbitrary" (quotes because "arbitrary" is a murky concept
itself), and
2. was intrinsic, as much as possible, to the body itself.
"At least as big as Pluto" (or Mercury) has a very arbitrary feel.
"Gravitationally round" is a reasonably well-defined characterization.
Of course roundness is a matter of degree, but still, it does create a
reasonable devision between two classes of objects.
Everyone agrees that planets have to orbit stars, so that's one factor
that's not intrinsic to the object itself that had to be included in
the definitio. But Mike Brown (and others) had proposed that a planet
should have to be more massive than all other bodies in similar orbits
combined. People who didn't like that definition felt that it depended
too much on the contingent presence or absence of other objects. Take
a non-planet, move it to a different star, and, poof! a planet.
I agree that non-arbitrariness and intrinsicness are nice properties
for a definition. But there are other nice properties too. It's good
if a definition
1. reflects previous usage,
2. pulls out the category of objects you're actually interested in, and
3. sticks.
Now, I'm an anti-Plutonian, so I'm not *entirely* committed to previous
usage. But traditionally the term 'planet' has been used for the
principal bodies in the Solar System (besides the Sun). The planets
are the ones worth memorizing. I claim that is the *most important*
thing the definition has to satisfy.
This is really tied in with point 2. The IAU needs this definition
because they have different committees for naming planets and minor
planets. The *reason* they have different committees is that a new
planet is a Big Deal. Discovering one gives you a special place in
scientific history, and there ought to be different conventions for
naming them. So why did they go off and choose a definition that is
eventually going to pull in dozens of objects? Schoolkids can
reasonably learn 12 planets, but a laminated placemat updated annually
with a large and growing number of obscure KBOs is not going to be very
informative.
And that's why the definition won't stick. Over the years a consensus
will emerge that the four Terrestrials and the four Jovians are the
major planets, and the other stuff is just detritus. There will be
lots of fodder for "gotcha" trivia questions, since there will be lots
of things that are technically planets but not seriously thought of as
such by anybody. (The more frequently a word W gets used in the phrase
"X is technically a W", the less satisfactory the definition is.)
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Date: 18 Aug 2006 13:21:24
From: Greg Crinklaw
Subject: Re: The IAU Draft Definition of 'Planet' and 'Plutons'
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Hi Mark,
I agree. I think your comments are very insightful and your reasoning
sound. There can be no reasonable scientific definition of "planet."
There are so many practical problems the proposed solution would cause.
Off the top of my head it would:
* complicate teaching kids about the solar system
* add minor objects to what is supposed to be, by definition, a list of
major bodies
* make it difficult to organize astronomy texts and lectures
* create embarrassing ongoing debates about new bodies being planets or not
* result in ridicule of the astronomical community
* cause educators to have to update educational materials continually
* cause headaches for so many people that are difficult to truly grasp.
As an example, what if you were the web master of nineplanets.com?
Or, in my case, the developer of a software product that intrinsically
treats planets differently from Ceres or "Xena?" in many ways and can't
easily include Charon?
As you put it, with all these practical issues it won't likely "stick."
I've been a proponent of keeping Pluto as a planet, mostly because of
deference to history combined with the practical problems demoting it
would cause. There simply didn't seem to be a compelling reason not to
keep Pluto.
But if I were a voting member of the IAU I'd reconsider in an instant,
given the chaos the current proposal would cause. Let the icy bodies in
our solar system be not planets. Icy bodies are distinctly different in
composition and in where and how they form. And there is a natural
limit to how large they can be without becoming gas giants.
So a definition of "planet" I could support would be the current
proposal but with the stipulation that bodies primarily composed of ice
would not be included. That would eliminate Pluto and "Xena" and very
likely all future discoveries in the outer solar system.
It would also avoid 90% of the practical issues above, even though it
effectively replaces Pluto with Ceres.
mark.foskey@gmail.com wrote:
> This is a bad definition, and the reason they got it wrong is that used
> the wrong set of criteria for a "good definition".
>
> Looking at how they defend their draft, I see that they were looking
> for a definition that
> 1. was "not arbitrary" (quotes because "arbitrary" is a murky concept
> itself), and
> 2. was intrinsic, as much as possible, to the body itself.
>
> "At least as big as Pluto" (or Mercury) has a very arbitrary feel.
> "Gravitationally round" is a reasonably well-defined characterization.
> Of course roundness is a matter of degree, but still, it does create a
> reasonable devision between two classes of objects.
>
> Everyone agrees that planets have to orbit stars, so that's one factor
> that's not intrinsic to the object itself that had to be included in
> the definitio. But Mike Brown (and others) had proposed that a planet
> should have to be more massive than all other bodies in similar orbits
> combined. People who didn't like that definition felt that it depended
> too much on the contingent presence or absence of other objects. Take
> a non-planet, move it to a different star, and, poof! a planet.
>
> I agree that non-arbitrariness and intrinsicness are nice properties
> for a definition. But there are other nice properties too. It's good
> if a definition
> 1. reflects previous usage,
> 2. pulls out the category of objects you're actually interested in, and
> 3. sticks.
>
> Now, I'm an anti-Plutonian, so I'm not *entirely* committed to previous
> usage. But traditionally the term 'planet' has been used for the
> principal bodies in the Solar System (besides the Sun). The planets
> are the ones worth memorizing. I claim that is the *most important*
> thing the definition has to satisfy.
>
> This is really tied in with point 2. The IAU needs this definition
> because they have different committees for naming planets and minor
> planets. The *reason* they have different committees is that a new
> planet is a Big Deal. Discovering one gives you a special place in
> scientific history, and there ought to be different conventions for
> naming them. So why did they go off and choose a definition that is
> eventually going to pull in dozens of objects? Schoolkids can
> reasonably learn 12 planets, but a laminated placemat updated annually
> with a large and growing number of obscure KBOs is not going to be very
> informative.
>
> And that's why the definition won't stick. Over the years a consensus
> will emerge that the four Terrestrials and the four Jovians are the
> major planets, and the other stuff is just detritus. There will be
> lots of fodder for "gotcha" trivia questions, since there will be lots
> of things that are technically planets but not seriously thought of as
> such by anybody. (The more frequently a word W gets used in the phrase
> "X is technically a W", the less satisfactory the definition is.)
>
--
Greg Crinklaw
Astronomical Software Developer
Cloudcroft, New Mexico, USA (33N, 106W, 2700m)
SkyTools: http://www.skyhound.com/cs.html
Observing: http://www.skyhound.com/sh/skyhound.html
Comets: http://www.skyhound.com/sh/comets.html
To reply take out your eye
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Date: 19 Aug 2006 15:13:51
From: Paul Schlyter
Subject: Re: 2006 IAU 12 planets resolution petition
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In article <44e5f6a4.7547484@news.qwest.net >,
SkySea <SkySea@aolREMOVE.com > wrote:
> I'll take a stab at a definition, and let the world rip it to shreds
> and come up with something better:
>
> "A planet is a aggregate of solid materials
That part of your definition would make the gas giants Jupiter,
Saturn, Uranus and Neptune non-planets.....
> constituting a primary
> mass (in the case of systems) shaped to spherical by gravity
> overcoming hydrostatic forces (in the absence of any rotational
> effects), in an orbit around a star (fusing or remnant) or within a
> star system."
--
----------------------------------------------------------------
Paul Schlyter, Grev Turegatan 40, SE-114 38 Stockholm, SWEDEN
e-mail: pausch at stockholm dot bostream dot se
WWW: http://stjarnhimlen.se/
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