Why I am satisfied with the new IAU definition of planet

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Date: 08 Sep 2006 12:26:27
From: Greg Crinklaw
Subject: Why I am satisfied with the new IAU definition of planet

I tried to post this to a Yahoo group but because of the narrow focus of
the groups I belong to, it is deemed an inappropriate subject. So I'll
toss it out to the wolves here instead.

It was inevitable that no matter what the IAU decided about the
definition of "planet" (even if they decided not to decide) there were
going to be a lot of people unhappy with the decision. The reality is
that astronomers have long been split on the status of Pluto as a planet
and obviously that split remains.

Going into the debate I was in favor of keeping Pluto as a planet.

Here are the things I felt should be accomplished by a definition of the
word. It should require:

(1) a non-arbitrary definition with a basis in science, having to do
with how planets form or a basic characteristic such as primary composition.

(2) a minimal impact on the societies of the world, unless justified
strongly by (1). In other words, let's not give up Pluto, and let's not
introduce dozens of new planets without a compelling reason to do so.

Because of the second point I felt Pluto should simply be left as it
was. I saw no sign that we understood the formation of the planets well
enough such that we would satisfy requirement (1). I saw no physical
distinction between "major" and "minor" bodies in the solar system to
easily fit our preconceived notions. It seemed like we were trying to
force an arbitrary distinction on a continuum.

But I was unaware of this:

http://arxiv.org/abs/astro-ph/0608359

From the abstract:
"A planet is an end product of disk accretion around a primary star or
substar. I quantify this definition by the degree to which a body
dominates the other masses that share its orbital zone. Theoretical and
observational measures of dynamical dominance reveal a gap of four to
five orders of magnitude separating the eight planets of our solar
system from the populations of asteroids and comets."

What this work does is conclude that there is in fact a clear
distinction for "a major solar system body" based on how these bodies
dominate their zone during the process that formed them. Pluto fails
this test completely, whereas the other planets pass it with flying
colors.

While the IAU definition of a planet failed to cite this work
implicitly, it was presumably understood by those voting that this was
the underlying basis; above is what is meant by "clearing its
neighborhood." I assume it is the intention of the IAU to define more
clearly what is meant by that statement in time--the statement itself is
meant only as a general principle.

This definition is based in the science of how planets and other bodies
form around a star. It satisfies my requirement No. 1 and, for me, it
satisfies it well enough to give up Pluto as a planet.

In the last week or so I've been thinking about this quite a bit; I've
looked at adopting the IAU definition for use in future versions of my
software. In doing so, I have been "living" with this new definition
and I'm surprised by how comfortable I have become with it.

One of the things I've been working on lately is how the asteroids are
classified with regard to their orbits. When you look at it from this
perspective it becomes pretty clear that Pluto is one of the largest and
certainly the brightest of the Scattered Disk Objects. That clearly
makes it special. But on par with Jupiter? The honest, objective answer
is no.

It took me a while, but I've come to really like the idea of a dwarf
planet class: bodies that stand out from the rest of the rubble because
they are massive enough to be round, yet have not come to dominate their
surroundings in the same way that Jupiter or even Mercury have. Pluto is
now the prototype of this new class of objects, which is a fitting
tribute to its discoverer. Ceres is now elevated to a status that it
deserves, and I hope more attention will be paid to it in the future
because of it. And finally, 2003 UB313 (Xena) and the many other
similar large objects in the outer solar system have a class to call
their own.

So, who is going to be the first to see all three dwarf planets? Ceres
is easy. It can be seen in any telescope (or even large binoculars).
Pluto is visible in a six-inch from a dark site, although an eight-inch
or larger is probably best. Xena *might* be glimpsed in a 40-inch
scope... but it can be detected in amateur instruments equipped with an
imager. And they are well placed for observation this month!

Clear skies,
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

Date: 08 Sep 2006 14:41:25
From: canopus56
Subject: Re: Why I am satisfied with the new IAU definition of planet

Alson Wong wrote:
> Here's a quick link to the information listed in Table 1 of the article:
> http://en.wikipedia.org/wiki/List_of_solar_system_objects_by_planetary_discriminant

Here is a similar table that I threw together from Soter's Tables 1, 2a
and 2b, listing by orbital radius, the earth masses of the solar system
body, the earth masses of the debris field and Soter's planetary
discriminate - the ratio of the two.

http://members.csolutions.net/fisherka/astronote/notes/PlanetDebrisRatio.html

- Canopus56

Date: 09 Sep 2006 16:12:23
From: Alson Wong
Subject: Re: Why I am satisfied with the new IAU definition of planet

"canopus56" <canopus56@yahoo.com > wrote in message
news:1157751685.664996.101270@i3g2000cwc.googlegroups.com...
> Here is a similar table that I threw together from Soter's Tables 1, 2a
> and 2b, listing by orbital radius, the earth masses of the solar system
> body, the earth masses of the debris field and Soter's planetary
> discriminate - the ratio of the two.
>
> http://members.csolutions.net/fisherka/astronote/notes/PlanetDebrisRatio.html
>
> - Canopus56

Nice summary, thanks.

Date: 08 Sep 2006 14:23:35
From: Alson Wong
Subject: Re: Why I am satisfied with the new IAU definition of planet

"Greg Crinklaw" <theskyhoundyoureye@yahoo.com > wrote in message
news:47361$4501b5c6$4212a5f6$2174@TULAROSA.NET...
>I tried to post this to a Yahoo group but because of the narrow focus of
> the groups I belong to, it is deemed an inappropriate subject. So I'll
> toss it out to the wolves here instead.
>
> It was inevitable that no matter what the IAU decided about the
> definition of "planet" (even if they decided not to decide) there were
> going to be a lot of people unhappy with the decision. The reality is
> that astronomers have long been split on the status of Pluto as a planet
> and obviously that split remains.
>
> Going into the debate I was in favor of keeping Pluto as a planet.
>
> Here are the things I felt should be accomplished by a definition of the
> word. It should require:
>
> (1) a non-arbitrary definition with a basis in science, having to do
> with how planets form or a basic characteristic such as primary
> composition.
>
> (2) a minimal impact on the societies of the world, unless justified
> strongly by (1). In other words, let's not give up Pluto, and let's not
> introduce dozens of new planets without a compelling reason to do so.
>
> Because of the second point I felt Pluto should simply be left as it
> was. I saw no sign that we understood the formation of the planets well
> enough such that we would satisfy requirement (1). I saw no physical
> distinction between "major" and "minor" bodies in the solar system to
> easily fit our preconceived notions. It seemed like we were trying to
> force an arbitrary distinction on a continuum.
>
> But I was unaware of this:
>
> http://arxiv.org/abs/astro-ph/0608359

Here's a quick link to the information listed in Table 1 of the article:
http://en.wikipedia.org/wiki/List_of_solar_system_objects_by_planetary_discriminant

Date: 08 Sep 2006 13:34:20
From: oriel36
Subject: Re: Why I am satisfied with the new IAU definition of planet

Show kids ,using actual images of Jupiter and Saturn,how the faster
Earth overtakes the slower moving outer planets and they will love how
Copernicus figured out that the Earth and the other planets move around
the Sun .

Tell them how astronomers for over a thousand years seen the planets
move forwards,backwards and forwards against the background stars -

http://antwrp.gsfc.nasa.gov/apod/image/0112/jupsatloop_tezel.jpg

Then tell them that when you put the images together you get to see
the Earth moving around the Sun by moving faster than the outer planets
-

http://antwrp.gsfc.nasa.gov/apod/image/0112/JuSa2000_tezel.gif

This is what astronomers do !.

A historical artifact for students who become familiar with the
Copernican reasoning is to acknowledge that the dynamicists beginning
with Newton could not even get this right.

"For to the earth planetary motions appear sometimes direct, sometimes
stationary, nay, and sometimes retrograde. But from the sun they are
always seen direct," Newton

Nay indeed Isaac ! ,who wants to be the first astrophotographer to
acknowledge that planetary motions around the Sun are seen directly
from Earth ?.

Greg Crinklaw wrote:
> Phil Wheeler wrote:
> > Greg Crinklaw wrote:
> >
> >> (2) a minimal impact on the societies of the world,
> >
> > What society, what culture, could care one whit if Pluto is a planet or
> > not .. or even if it vanished tomorrow?
> >
> > I don't get that part, Greg.
>
> That was meant to be a very general comment to describe the world of
> people directly affected by the definition. To expand on it with some
> specific examples: the third grade classroom at the local elementary
> school that has the planets on the walls in their hallway; the display
> at the Planetarium downtown; the author trying to organize an Astronomy
> 101 textbook; the software developer designing an interface with classes
> of objects; the amateur astronomer who wants to see all the planets in
> her telescope... that sort of thing. You say nobody really cares, and
> maybe they don't, yet the definition of planet clearly can affect huge
> numbers of people worldwide.
>
> I'd simply rather not rock their boats without good reason. Thankfully,
> in my opinion, they found just enough reason to justify it.
>
> Clear skies,
> 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

Date: 08 Sep 2006 19:52:42
From: Phil Wheeler
Subject: Re: Why I am satisfied with the new IAU definition of planet

Greg Crinklaw wrote:

> (2) a minimal impact on the societies of the world,

What society, what culture, could care one whit if
Pluto is a planet or not .. or even if it vanished
tomorrow?

I don't get that part, Greg.

Phil

Date: 08 Sep 2006 21:36:19
From: Chris L Peterson
Subject: Re: Why I am satisfied with the new IAU definition of planet

On Fri, 08 Sep 2006 19:52:42 GMT, Phil Wheeler <wt6uh-ng7@yahoo.com >
wrote:

>What society, what culture, could care one whit if
>Pluto is a planet or not .. or even if it vanished
>tomorrow?

People obviously _do_ care, given all the petitions, discussions, and
general articles circulating outside the astronomical community.

These kind of things do become part of a society's fabric.

_________________________________________________

Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

Date: 09 Sep 2006 00:25:59
From: Florian
Subject: Re: Why I am satisfied with the new IAU definition of planet

>People obviously _do_ care, given all the petitions, discussions, and
>general articles circulating outside the astronomical community.

No kidding....

California Assembly Bill HR 36 Relative to Pluto's planetary status
http://www.spaceref.com/news/viewsr.html?pid=3D21982

.Florian

Date: 09 Sep 2006 01:43:43
From: Phil Wheeler
Subject: Re: Why I am satisfied with the new IAU definition of planet

Date: 08 Sep 2006 18:50:22
From: Greg Crinklaw
Subject: Re: Why I am satisfied with the new IAU definition of planet

Florian wrote:
>> People obviously _do_ care, given all the petitions, discussions, and
>> general articles circulating outside the astronomical community.
>
>
> No kidding....
>
> California Assembly Bill HR 36 Relative to Pluto's planetary status
> http://www.spaceref.com/news/viewsr.html?pid=21982

The "mean-spirited IAU...", "The deletion of Pluto as a planet is a
hasty, ill-considered scientific heresy similar to questioning the
Copernican theory...", (LOL) and of course my favorite, "The downgrading
of Pluto reduces the number of planets available for legislative leaders
to hide redistricting legislation and other inconvenient political
reform measures;"

Somebody has a wicked sense of humor! I'm impressed.

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

Date: 09 Sep 2006 00:37:04
From: Pierre Vandevennne
Subject: Re: Why I am satisfied with the new IAU definition of planet

"Florian" <star6@TheDesertSon.com > wrote in news:rSnMg.2315$%i.1624
@tornado.socal.rr.com:

> http://www.spaceref.com/news/viewsr.html?pid=21982

Hehe. Demoting Pluto was just a smokescreen: while you Americans are
getting all worked up about that they elect a ... French woman to the
presidency of the IAU

Pierre

Date: 09 Sep 2006 01:45:14
From: Phil Wheeler
Subject: Re: Why I am satisfied with the new IAU definition of planet

Pierre Vandevennne wrote:
> "Florian" <star6@TheDesertSon.com> wrote in news:rSnMg.2315$%i.1624
> @tornado.socal.rr.com:
>
>> http://www.spaceref.com/news/viewsr.html?pid=21982
>
> Hehe. Demoting Pluto was just a smokescreen: while you Americans are
> getting all worked up about that they elect a ... French woman to the
> presidency of the IAU
>

Obviously downgrading Pluto is a nasty scheme of
the plutocrats of France :)

Phil

Date: 08 Sep 2006 22:35:07
From: Richard Adams
Subject: Re: Why I am satisfied with the new IAU definition of planet

Phil Wheeler wrote:
> Pierre Vandevennne wrote:
>
>> "Florian" <star6@TheDesertSon.com> wrote in news:rSnMg.2315$%i.1624
>> @tornado.socal.rr.com:
>>
>>> http://www.spaceref.com/news/viewsr.html?pid=21982
>>
>>
>> Hehe. Demoting Pluto was just a smokescreen: while you Americans are
>> getting all worked up about that they elect a ... French woman to the
>> presidency of the IAU
>>
>
> Obviously downgrading Pluto is a nasty scheme of the plutocrats of
> France :)
>
> Phil

They're still out to get Lance Armstrong?

Date: 09 Sep 2006 09:11:09
From: Phil Wheeler
Subject: Re: Why I am satisfied with the new IAU definition of planet

Richard Adams wrote:
> Phil Wheeler wrote:
>> Pierre Vandevennne wrote:
>>
>>> "Florian" <star6@TheDesertSon.com> wrote in news:rSnMg.2315$%i.1624
>>> @tornado.socal.rr.com:
>>>
>>>> http://www.spaceref.com/news/viewsr.html?pid=21982
>>>
>>>
>>> Hehe. Demoting Pluto was just a smokescreen: while you Americans are
>>> getting all worked up about that they elect a ... French woman to the
>>> presidency of the IAU
>>>
>>
>> Obviously downgrading Pluto is a nasty scheme of the plutocrats of
>> France :)
>>
>> Phil
>
>
> They're still out to get Lance Armstrong?

Reckon they'll have to settle for Floyd Landis,
who does appear to have emulated Pluto's descent
into dwarfdom.

Date: 10 Sep 2006 01:12:24
From: Wally
Subject: Re: Why I am satisfied with the new IAU definition of planet

Pierre Vandevennne wrote:

> "Florian" <star6@TheDesertSon.com> wrote in news:rSnMg.2315$%i.1624
> @tornado.socal.rr.com:
>
> > http://www.spaceref.com/news/viewsr.html?pid=21982
>
> Hehe. Demoting Pluto was just a smokescreen: while you Americans are
> getting all worked up about that they elect a ... French woman to the
> presidency of the IAU
>

Has barely been mentioned in our press. Obviously you think its a big
deal!
Now who has the Inferiority Complex? And you had better check her family

tree sometime soon! French? (laughing)

>
> Pierre

Date: 10 Sep 2006 23:15:11
From: Pierre Vandevennne
Subject: Re: Why I am satisfied with the new IAU definition of planet

Wally <woodfield@ai5.net > wrote in news:4503ACC8.E07D04FE@ai5.net:

> Has barely been mentioned in our press. Obviously you think its a big
> deal!
> Now who has the Inferiority Complex? And you had better check her family

Hmmmm, I was sure I'd stumble on someone like you.... :-)

PS: I am not French. But yes, before you ask, my ancestors were apes.

Date: 08 Sep 2006 14:17:10
From: Greg Crinklaw
Subject: Re: Why I am satisfied with the new IAU definition of planet

Phil Wheeler wrote:
> Greg Crinklaw wrote:
>
>> (2) a minimal impact on the societies of the world,
>
> What society, what culture, could care one whit if Pluto is a planet or
> not .. or even if it vanished tomorrow?
>
> I don't get that part, Greg.

That was meant to be a very general comment to describe the world of
people directly affected by the definition. To expand on it with some
specific examples: the third grade classroom at the local elementary
school that has the planets on the walls in their hallway; the display
at the Planetarium downtown; the author trying to organize an Astronomy
101 textbook; the software developer designing an interface with classes
of objects; the amateur astronomer who wants to see all the planets in
her telescope... that sort of thing. You say nobody really cares, and
maybe they don't, yet the definition of planet clearly can affect huge
numbers of people worldwide.

I'd simply rather not rock their boats without good reason. Thankfully,
in my opinion, they found just enough reason to justify it.

Clear skies,
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

Date: 10 Sep 2006 01:08:54
From: Wally
Subject: Re: Why I am satisfied with the new IAU definition of planet

Phil Wheeler wrote:

> Greg Crinklaw wrote:
>
> > (2) a minimal impact on the societies of the world,
>
> What society, what culture, could care one whit if
> Pluto is a planet or not .. or even if it vanished
> tomorrow?
>
> I don't get that part, Greg.
>

Its the part you obviously are not a part of -

>
> Phil

Date: 08 Sep 2006 12:49:35
From: oriel36
Subject: Re: Why I am satisfied with the new IAU definition of planet

Greg Crinklaw wrote:
> I tried to post this to a Yahoo group but because of the narrow focus of
> the groups I belong to, it is deemed an inappropriate subject. So I'll
> toss it out to the wolves here instead.
>
> It was inevitable that no matter what the IAU decided about the
> definition of "planet" (even if they decided not to decide) there were
> going to be a lot of people unhappy with the decision. The reality is
> that astronomers have long been split on the status of Pluto as a planet
> and obviously that split remains.
>

People are not unhappy,they are irritated .

"The first planet to be discovered was Uranus by William and Caroline
Herschel on 13 March 1781. It was discovered by the fact that it showed
a disk when viewed through even a fairly low powered telescope. The
only other planets which have been discovered are Neptune and Pluto.
These were predicted using ingenious mathematical arguments based on
Newton's laws of gravitation and then observed near their predicted
locations. "

http://www-groups.dcs.st-and.ac.uk/~history/HistTopics/Neptune_and_Pluto.html

All those wonderful arguments and references that go to support
celestial mechanics now have to rewritten to suggest otherwise,if there
actually were astronomers they would tell you about shooting yourselves
in the foot with this one.

It is comical the way this is all unfolding,it truly is.

> Going into the debate I was in favor of keeping Pluto as a planet.
>
> Here are the things I felt should be accomplished by a definition of the
> word. It should require:
>
> (1) a non-arbitrary definition with a basis in science, having to do
> with how planets form or a basic characteristic such as primary composition.
>
> (2) a minimal impact on the societies of the world, unless justified
> strongly by (1). In other words, let's not give up Pluto, and let's not
> introduce dozens of new planets without a compelling reason to do so.
>
> Because of the second point I felt Pluto should simply be left as it
> was. I saw no sign that we understood the formation of the planets well
> enough such that we would satisfy requirement (1). I saw no physical
> distinction between "major" and "minor" bodies in the solar system to
> easily fit our preconceived notions. It seemed like we were trying to
> force an arbitrary distinction on a continuum.
>
> But I was unaware of this:
>
> http://arxiv.org/abs/astro-ph/0608359
>
> From the abstract:
> "A planet is an end product of disk accretion around a primary star or
> substar. I quantify this definition by the degree to which a body
> dominates the other masses that share its orbital zone. Theoretical and
> observational measures of dynamical dominance reveal a gap of four to
> five orders of magnitude separating the eight planets of our solar
> system from the populations of asteroids and comets."
>
> What this work does is conclude that there is in fact a clear
> distinction for "a major solar system body" based on how these bodies
> dominate their zone during the process that formed them. Pluto fails
> this test completely, whereas the other planets pass it with flying
> colors.
>
> While the IAU definition of a planet failed to cite this work
> implicitly, it was presumably understood by those voting that this was
> the underlying basis; above is what is meant by "clearing its
> neighborhood." I assume it is the intention of the IAU to define more
> clearly what is meant by that statement in time--the statement itself is
> meant only as a general principle.
>
> This definition is based in the science of how planets and other bodies
> form around a star. It satisfies my requirement No. 1 and, for me, it
> satisfies it well enough to give up Pluto as a planet.
>
> In the last week or so I've been thinking about this quite a bit; I've
> looked at adopting the IAU definition for use in future versions of my
> software. In doing so, I have been "living" with this new definition
> and I'm surprised by how comfortable I have become with it.
>
> One of the things I've been working on lately is how the asteroids are
> classified with regard to their orbits. When you look at it from this
> perspective it becomes pretty clear that Pluto is one of the largest and
> certainly the brightest of the Scattered Disk Objects. That clearly
> makes it special. But on par with Jupiter? The honest, objective answer
> is no.
>
> It took me a while, but I've come to really like the idea of a dwarf
> planet class: bodies that stand out from the rest of the rubble because
> they are massive enough to be round, yet have not come to dominate their
> surroundings in the same way that Jupiter or even Mercury have. Pluto is
> now the prototype of this new class of objects, which is a fitting
> tribute to its discoverer. Ceres is now elevated to a status that it
> deserves, and I hope more attention will be paid to it in the future
> because of it. And finally, 2003 UB313 (Xena) and the many other
> similar large objects in the outer solar system have a class to call
> their own.
>
> So, who is going to be the first to see all three dwarf planets? Ceres
> is easy. It can be seen in any telescope (or even large binoculars).
> Pluto is visible in a six-inch from a dark site, although an eight-inch
> or larger is probably best. Xena *might* be glimpsed in a 40-inch
> scope... but it can be detected in amateur instruments equipped with an
> imager. And they are well placed for observation this month!
>
> Clear skies,
> 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

Date: 09 Sep 2006 17:35:25
From: canopus56
Subject: Re: Why I am satisfied with the new IAU definition of planet

Alson Wong wrote:
> > http://members.csolutions.net/fisherka/astronote/notes/PlanetDebrisRatio.html
>
> Nice summary, thanks.

In looking at Soter's tables more closely, I don't like where he puts
the Centaurs (" > 5 a.u."). Seems like those ought to be out around 15
a.u. It would be nice if there was a separate category for the Trojan
asteriods and maybe subdivide the Trans-Neptunian Objects into Kupier,
Scattered Disk and Oort. - Canopus56

Date: 09 Sep 2006 23:21:31
From: Alson Wong
Subject: Re: Why I am satisfied with the new IAU definition of planet

"canopus56" <canopus56@yahoo.com > wrote in message
news:1157848525.069207.309460@i3g2000cwc.googlegroups.com...
> Alson Wong wrote:
>> > http://members.csolutions.net/fisherka/astronote/notes/PlanetDebrisRatio.html
>>
>> Nice summary, thanks.
>
> In looking at Soter's tables more closely, I don't like where he puts
> the Centaurs ("> 5 a.u."). Seems like those ought to be out around 15
> a.u. It would be nice if there was a separate category for the Trojan
> asteriods and maybe subdivide the Trans-Neptunian Objects into Kupier,
> Scattered Disk and Oort. - Canopus56

Most Centaurs orbit between 5 and 30 AU, so " > 5 AU" is reasonable IMO (see
http://en.wikipedia.org/wiki/Image:TheKuiperBelt_42AU_Centaurs.svg). I don't
think the Trojan asteroids should be listed as a separate group since
they're bound to Jupiter's orbit at L4 and L5. Neptune also has several
objects at its L4 point. Soter does list asteroids, KBOs and the Oort cloud
separately as "primary reservoirs of colliding objects."

Date: 09 Sep 2006 14:27:54
From: Erik
Subject: Re: Why I am satisfied with the new IAU definition of planet

Greg Crinklaw wrote:
> Florian wrote:
> >> People obviously _do_ care, given all the petitions, discussions, and
> >> general articles circulating outside the astronomical community.
> >
> >
> > No kidding....
> >
> > California Assembly Bill HR 36 Relative to Pluto's planetary status
> > http://www.spaceref.com/news/viewsr.html?pid=21982
>
> The "mean-spirited IAU...", "The deletion of Pluto as a planet is a
> hasty, ill-considered scientific heresy similar to questioning the
> Copernican theory...", (LOL) and of course my favorite, "The downgrading
> of Pluto reduces the number of planets available for legislative leaders
> to hide redistricting legislation and other inconvenient political
> reform measures;"
>
> Somebody has a wicked sense of humor! I'm impressed.
>
> Greg
>
I looked this up on the official CA legislative website just to make
sure this was not a joke -- I cannot believe my state legislature
sometime. Do any of this bill's sponsers even have ANY astronomy
background, much less astrophysics or mathematics?

Beyond that, the IAU aside (I am still fence-sitting myself on the
controversy), I cannot believe all of the people who are claiming that
"textbooks will have to be rewritten" and "displays will have to be
changed." Nonsense. Which textbooks will have to be rewritten before
their normally (very short) revision cycle? Any decent K-12 teacher
will use that section of the book, revised or not, as a teaching moment
to discuss how scientific consensus is or is not achieved, and how
difficult it is to come up with clear definitions in science. Any
college-level course aimed at GE or non-science majors will likely take
the same approach. For upper-division courses, a good professor who is
interested in teaching will likely assign a couple of journal articles
anyway. And for graduate students, it would seem that if you are
taking a course that involves a discussion of Pluto, its definition as
a planet or not would be a secondary consideration, seeing how there
has not been scientific consensus on this issue before the recent IAU
meeting.

As for museums, planeteriums and other displays, why remove Pluto? It
would be better, imho, to add material (signage, verbiage or sidebar to
a brochure) that explains the planetary definition controversy in
layman's terms. I think it is clear to all of us that this discussion
is far from concluded, and ultimately as astronomers, we care more
about what Pluto IS than what it is NOT.

socalsw
Erik

Date: 09 Sep 2006 17:28:07
From: Greg Crinklaw
Subject: Re: Why I am satisfied with the new IAU definition of planet

Erik wrote:
> Greg Crinklaw wrote:
>> Florian wrote:
>>>> People obviously _do_ care, given all the petitions, discussions, and
>>>> general articles circulating outside the astronomical community.
>>>
>>> No kidding....
>>>
>>> California Assembly Bill HR 36 Relative to Pluto's planetary status
>>> http://www.spaceref.com/news/viewsr.html?pid=21982
>> The "mean-spirited IAU...", "The deletion of Pluto as a planet is a
>> hasty, ill-considered scientific heresy similar to questioning the
>> Copernican theory...", (LOL) and of course my favorite, "The downgrading
>> of Pluto reduces the number of planets available for legislative leaders
>> to hide redistricting legislation and other inconvenient political
>> reform measures;"
>>
>> Somebody has a wicked sense of humor! I'm impressed.
>>
>> Greg
>>
> I looked this up on the official CA legislative website just to make
> sure this was not a joke -- I cannot believe my state legislature
> sometime. Do any of this bill's sponsers even have ANY astronomy
> background, much less astrophysics or mathematics?

Of course it's a joke--that's just it. This is rather well written
satire. My faith in elected officials went up a notch. ;-) I don't
know if they are poking fun at themselves or their colleagues, but I'd
be surprised if there isn't a certain degree of "inside joke" going on.

Clear skies,
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

Date: 09 Sep 2006 22:34:35
From: Florian
Subject: Re: Why I am satisfied with the new IAU definition of planet

>I looked this up on the official CA legislative website just to make
>sure this was not a joke -- I cannot believe my state legislature
>sometime. Do any of this bill's sponsers even have ANY astronomy
>background, much less astrophysics or mathematics?

I think it was meant in fun. At least i found it funny.=20

;-)

.Florian

Date: 10 Sep 2006 01:06:22
From: Wally
Subject: Re: Why I am satisfied with the new IAU definition of planet

Greg Crinklaw wrote:

> I tried to post this to a Yahoo group but because of the narrow focus of
> the groups I belong to, it is deemed an inappropriate subject. So I'll
> toss it out to the wolves here instead.
>
> It was inevitable that no matter what the IAU decided about the
> definition of "planet" (even if they decided not to decide) there were
> going to be a lot of people unhappy with the decision. The reality is
> that astronomers have long been split on the status of Pluto as a planet
> and obviously that split remains.
>
> Going into the debate I was in favor of keeping Pluto as a planet.
>
> Here are the things I felt should be accomplished by a definition of the
> word. It should require:
>
> (1) a non-arbitrary definition with a basis in science, having to do
> with how planets form or a basic characteristic such as primary composition.
>
> (2) a minimal impact on the societies of the world, unless justified
> strongly by (1). In other words, let's not give up Pluto, and let's not
> introduce dozens of new planets without a compelling reason to do so.
>
> Because of the second point I felt Pluto should simply be left as it
> was. I saw no sign that we understood the formation of the planets well
> enough such that we would satisfy requirement (1). I saw no physical
> distinction between "major" and "minor" bodies in the solar system to
> easily fit our preconceived notions. It seemed like we were trying to
> force an arbitrary distinction on a continuum.
>
> But I was unaware of this:
>
> http://arxiv.org/abs/astro-ph/0608359
>
> From the abstract:
> "A planet is an end product of disk accretion around a primary star or
> substar. I quantify this definition by the degree to which a body
> dominates the other masses that share its orbital zone. Theoretical and
> observational measures of dynamical dominance reveal a gap of four to
> five orders of magnitude separating the eight planets of our solar
> system from the populations of asteroids and comets."
>
> What this work does is conclude that there is in fact a clear
> distinction for "a major solar system body" based on how these bodies
> dominate their zone during the process that formed them. Pluto fails
> this test completely, whereas the other planets pass it with flying
> colors.
>
> While the IAU definition of a planet failed to cite this work
> implicitly, it was presumably understood by those voting that this was
> the underlying basis; above is what is meant by "clearing its
> neighborhood." I assume it is the intention of the IAU to define more
> clearly what is meant by that statement in time--the statement itself is
> meant only as a general principle.

In other words, the IAU failed to clear its own orbital zone?

>
>
> This definition is based in the science of how planets and other bodies
> form around a star. It satisfies my requirement No. 1 and, for me, it
> satisfies it well enough to give up Pluto as a planet.

So in other words, the word planet is now a code word for a "formative
process"?
And if this is/are true, then lets get this business of "clearing a
neighborhood" down
straight - pleeeez!? It isnt the "planetesimalista" (or the accretion disk) that
clears
itself? In other words, stellar formation is not static and benign during the
same periods accretion disks are supposedly politely sweep their neighborhoods
clean, gravitationally?

So "planet" is now time-dependent? Not just a "wanderer" in the here and now
but something with a scientifically provable formative history?

And not just an object perhaps with satellites within a certain specified zone
around a parent star, but anything beyond the magical line is a Kuipertino?

>
>
> In the last week or so I've been thinking about this quite a bit; I've
> looked at adopting the IAU definition for use in future versions of my
> software.

Sales will follow of course. Then redefine star, constellation, and RA & DEC
must be dispensed with also! Sales will followeth!

> In doing so, I have been "living" with this new definition
> and I'm surprised by how comfortable I have become with it.
>
> One of the things I've been working on lately is how the asteroids are
> classified with regard to their orbits. When you look at it from this
> perspective it becomes pretty clear that Pluto is one of the largest and
> certainly the brightest of the Scattered Disk Objects.

Scatterinos of the Diskotinos! O-yeh ay-Kay?

> That clearly
> makes it special. But on par with Jupiter? The honest, objective answer
> is no.

Was there a serious juxtaposition of Jupiter with Pluto? For what purpose?
Little Juplutinos?

>
>
> It took me a while, but I've come to really like the idea of a dwarf
> planet class:

There already was major vs minor planets.

> bodies that stand out from the rest of the rubble because
> they are massive enough to be round, yet have not come to dominate their
> surroundings in the same way that Jupiter or even Mercury have.

There is something in this that smacks of deep unrealism.

> Pluto is
> now the prototype of this new class of objects, which is a fitting
> tribute to its discoverer. Ceres is now elevated to a status that it
> deserves, and I hope more attention will be paid to it in the future
> because of it. And finally, 2003 UB313 (Xena) and the many other
> similar large objects in the outer solar system have a class to call
> their own.

Good sales pitch.

>
>
> So, who is going to be the first to see all three dwarf planets?

The same as always saw the same minor planets!

> Ceres
> is easy. It can be seen in any telescope (or even large binoculars).
> Pluto is visible in a six-inch from a dark site, although an eight-inch
> or larger is probably best. Xena *might* be glimpsed in a 40-inch
> scope... but it can be detected in amateur instruments equipped with an
> imager. And they are well placed for observation this month!
>

And what is gained that was not already there? More and clearly labeled address

signs on every road in the county, I think. Should generate more sales and more
intrusive commercialism but science?

>
> Clear skies,
> 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

Date: 10 Sep 2006 08:40:48
From: Greg Crinklaw
Subject: Re: Why I am satisfied with the new IAU definition of planet

Wally trolled some nonsense and got the PLONK

BUZZZ. Change your pseudonym and try again.

--
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

Date: 10 Sep 2006 10:55:20
From: oriel36
Subject: Re: Why I am satisfied with the new IAU definition of planet

The Earth's deviation from a perfect sphere is not an evolutionary
artifact,it is a consequence of the continuing rotational dynamics of a
molten/flexible interior.

The one thing that was availible to dynamicists to work with
productively from an astronomical point of view and they shut it off
!.It is absolutely uncanny how theorists can pick the major area to
work on and shut it off for a meaningless 'definitional treatment.

Again,the astro-imagers must be irritated beyond endurance.

Greg Crinklaw wrote:
> Wally trolled some nonsense and got the PLONK
>
> BUZZZ. Change your pseudonym and try again.
>
>
> --
> 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