[meteorite-list] Pluto May Get Demoted After All

From: Gerald Flaherty <grf2_at_meteoritecentral.com>
Date: Sat Aug 19 17:29:37 2006
Message-ID: <00e301c6c3d6$81f6f160$6402a8c0_at_Dell>

Oh, OK.
Jerry Flaherty
----- Original Message -----
From: "Sterling K. Webb" <sterling_k_webb_at_sbcglobal.net>
To: "Larry Lebofsky" <lebofsky_at_lpl.arizona.edu>; "Meteorite Mailing List"
<meteorite-list_at_meteoritecentral.com>; <cynapse@charter.net>
Sent: Saturday, August 19, 2006 3:34 AM
Subject: Re: [meteorite-list] Pluto May Get Demoted After All


> Hi, Darren,
>
>
> Unavoidable. The use of Pluto to refer allegorically to
> things in the depth, in the darkness, faraway, and dead, is
> centuries old. For more than a year here in the List, I've been
> using the term "Plutonian" instead, but geologists speak of
> "plutonian processes" and the like, so it's no better. I'm
> pretty sure that there are a few cases of "one field of science
> using a term with an established specific meaning in another
> field of science." I just can't think of them (it's too A.M.-ish).
>
> It all comes from regarding the "planet" Pluto as the
> prototype of a system of worlds, which it may, or may
> not, be. I personally think that is a lousy idea. We don't
> call the outer planets "Jupiterian" or "Jovian" worlds; we
> call them "gas giants." But we do call the inner planets
> "Terrestrial" worlds (after the Latin "Terra" for Earth).
> But "Terrestrial" planets is now considered a bastard term
> and professional scientists don't use it, I'm told...
>
> I've just been going through my mountain of old textbooks
> going back to the 1940's (I like to collect them) up to about
> the year 2000. I find the "Terrestrial" planets up through 1995.
> The categories used for planets vary with the emphasis and the
> bias of the writer. One has a section on "airless rocky bodies"
> which puts Io, Mercury and the Moon together, then a section
> on "icy rocky bodies" which puts Pluto, the Galilean satellites,
> Titan, and Triton together. All the differing varieties of organization
> are like creating your own categories of planetary types.
>
> Of course, if by a "pluton" you mean an icy rocky world,
> then Ganymede is the King, not Pluto. And indeed, the IAU
> says, in the draft of Resolution V: "these objects typically have
> highly inclined orbits with large eccentricities and orbital periods
> in excess of 200 years. We designate this category of planetary
> objects, of which Pluto is the prototype, as a new class that we
> call 'plutons'. "
> http://www.iau2006.org/mirror/www.iau.org/iau0601/iau0601_resolution.html
> So, Plutons have to be inclined, eccentric, and have an orbital
> period of 200 years or more... more or less. Not a compositional
> class, a locational class. They're Pluto's neighbors, not Plutoclones.
>
> I notice that everybody in the press is calling the "plutons"
> Dwarf Planets. Can't anybody read anymore? Back to the draft:
> "We recognize that Ceres is a planet by the above scientific definition.
> For historical reasons, one may choose to distinguish Ceres from
> the classical planets by referring to it as a 'dwarf planet'." This
> reading
> is further made clear in Footnote 3. There is apparently only ONE
> Dwarf Planet, and it's cute l'il Ceres.
>
> EVERYBODY is calling the Plutons Dwarves. This seems a
> strange reading of the text. "Dwarf" planets are in the zone of the
> Classical Planets, roughly circular orbits, moderate eccentricity,
> and ROUND, just not real big, according to the Draft Resolution.
>
> Then, there's "hydrostatic equilibrium," very strangely applied
> in the language of the Draft. Footnote 3 states that "If Pallas, Vesta,
> and/or Hygiea are found to be in hydrostatic equilibrium, they are
> also planets, and may be referred to as 'dwarf planets'." Now, a
> body is in hydrostatic equilibrium if IT DOESN'T MOVE internally
> or change its shape under the forces that are continuously applied
> to it. Therefore, ALL rigid bodies that do not change their shape
> are in hydrostatic equilibrium, if that ALONE is the criteria. Don't
> they mean in "hydrostatic equilibrium and round"? How round they
> gotta be? 95% round? 90% round? 85% round? 80% round? 80%
> is pretty round, but is it round enough? Jupiter is only 93.5% round;
> Ceres is 93% round. Saturn is only 90.2% round. Pallas is 87%
> round.
>
> Ceres is in hydrostatic equilibrium and is round (pretty much)
> and Vesta is in hydrostatic equilibrium and not round. BUT, Vesta
> (as we on this List happily know), little Vesta is a completely
> differentiated planetary body, iron core, rocky mantle, crust,
> the works. It must have been completely molten and plastic at
> some point; how come you ain't round, little Vesta? Well, looks
> like it was spinning crazily at the time and entered hydrostatic
> equilibrium while still in a state of dynamic and hydrostatic
> equilibrium as a tri-axial egg-thingee. (Then, it got whapped
> upside the south pole with something that left a crater 80%
> the diameter of Vesta which made it lose its enthusiasm for
> tri-axial revolution and settle down some...)
>
> I guess...
>
> So, Vesta might get to be a (dwarf) planet, if you could
> prove all that and the definition was clearer. As written, it seems
> also to offer some special permission for 2003EL61, a HUGE
> tri-axial egg-thingee (1960x1520x1000 km). I say HUGE because
> if it were round, it would be 1500 km across, 50% bigger than
> Ceres. The Footnote also mentions Hygiea and Pallas. Well,
> Pallas is 87% round but Hygiea is a blob, only 70% round, not
> a differentiated body. Why Hygiea? Well, it's bigger than Vesta...
> And somebody, by rooting through the lists, has found a 100 km
> asteroid that's really, really round; is it a planet?
>
> So the IAU scheme is: Eight Classical Planets, accompanied
> by one Dwarf Planet, and a Orcish rabble of Plutons and Small
> Bodies. Sounds like The Lord of the Rings to me.
>
> The Uruguayan alternative definition is stranger still. Obviously
> based on the zonal theory of planet formation, it holds that a planet
> is "by far the largest member of the local population of bodies."
> The whole thing rests on how you define "local." Everybody
> uses the planets out beyond Pluto, which they don't like anyway,
> to define a "locality" and disqualify Pluto. But that volume of
> space, as a zone, is far greater than the entire inner solar system.
> In fact, the inner solar system is tiny by comparison. You could put
> roughly 100 inner solar systems in the zone between 38 and 48 AU!
> So, if that's the size criteria, the inner solar system is a very "local"
> population. So, the Earth is a planet and Mercury, Venus, Mars
> and Ceres are not. Right?
> No, wait! He said, "largest by far," and the Earth is not larger
> "by far" than Venus; Venus is almost as big as the Earth, so that
> means that there is NO planet in the inner solar system -- it's just
> a blanketty-blank asteroid belt!
> I suspect that this is what comes of cooking up theories to
> fit your prejudices. Is that what the Uruguayan alternative means?
> No. Is that what it says? Yes. Why is the tiny 3 AU wide patch
> around the Sun so special as to have four planets in it? 'Cause
> we live there, and aren't we special...? The planets may go around
> the Sun, but the definition goes around the Earth.
>
> If you listen with your other ear to what Brown is saying
> when he says 53 bodies qualify as planets under the definition,
> he is saying in effect that he is finding roughly 10 planet candidates
> PER YEAR, has found them. Well, he and the others that hunt,
> but he seems to be the one that's bagging the game. Which may
> be why he says it could go as high as 100. That just means in 10
> more years, he'll find a conservative 50 more "planets." Maybe
> they'll all be small round icy bodies, but maybe not. He's looking
> "deeper" for "harder" objects, but the odds are good that
> there's a few big ones out there...
>
> We can't say "minor planets" anymore; they're Small Solar
> System Bodies. I suggest we all practice pronouncing "SiSSiB,"
> because nobody is going to say "Small Solar System Bodies"
> 20 times over, very fast. Meanwhile, we can still talk about
> "asteroids" which ARE NOT "little stars," which is what
> "asteroid" means.
>
> There may be a sound method to the sparse and incomplete
> Draft of Resolution V for GA XXVI. Ceres, Charon, and Xena
> get to be planets right away. They demonstrate the definition by
> applying it immediately to the Three Lucky Winners! One Dwarf,
> One Pluton, One Double Planet, and One IAU to Rule Them All.
> As for what the definitions mean, what other bodies get to be planets,
> well, that will have to be decided by Committees. Committees work
> slowly and deliberately. Committees try to consider everything.
> Committees listen to input. Committees take their time. Probably lots
> of time, during which Committee-paced time, more will become clear.
> Committees will help people settle their minds, adjust, get right with
> the world...
>
> Committees are wonderful things. And this may really be
> one of those times when we need them, for just the reasons we
> usually don't like them.
>
>
> Sterling K. Webb
> ------------------------------------------------------------------------------
> ----- Original Message -----
> From: "Darren Garrison" <cynapse_at_charter.net>
> To: "Meteorite Mailing List" <meteorite-list_at_meteoritecentral.com>
> Sent: Friday, August 18, 2006 10:52 PM
> Subject: Re: [meteorite-list] Pluto May Get Demoted After All
>
>
> On Fri, 18 Aug 2006 20:37:34 -0700, you wrote:
>
>>history community. These are people who know the issues, who know the
>>science
>>(the words and concepts are far from arbitrary),
>
> I realized something tonight that I knew but for some reason, it hadn't
> stuck me
> before: the word "pluton" already has a use in science. It is a "Body of
> magma
> which has solidified beneath the earth". I've been on a few of them, and
> can
> even see one from my house when I find the right gap between the trees
> (this
> one: http://www.shutterfreaks.com/gallery/album152/DSC_4055, photo not
> mine).
>
> So it makes me wonder-- does one field of science try to avoid reusing a
> term
> with an established specific meaning in another field of science (and
> would some
> far future geologist be looking for plutons on Plutons?)
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Received on Sat 19 Aug 2006 05:29:09 PM PDT