[meteorite-list] Pluto May Get Demoted After All

From: MexicoDoug <MexicoDoug_at_meteoritecentral.com>
Date: Fri Aug 18 15:38:22 2006
Message-ID: <00a401c6c2fd$cd1297a0$d3c85ec8_at_0019110394>

Hello Larry and Darren, OK, I checked your facts and I'll stuff the idea
about the Disney character where the Sun don't shine and it belongs. And
further I trust you. If you happen to have the British "girl's" email
address sure I'll send a message to further vindicate you and Darren.

As for the first P.D., I object to your mischaracterization on this issue of
public interest and the birthright we all have to express our opinions, even
baboons like myself. I never would criticize you for the failure you had on
reaching consensus while on the "Committee". On the contrary you and other
members have my respect as contributors, though I have a problem with the
committee's appointed authority. You have to admit, the astronomers must
be having a fun time...Are you trying to say that it is not fair game to
suggest that the committee has learned a lot but has a way to go, and are
you saying that the committee is right in not actively soliciting someone
like Saul Kripke as a member? If only astronomers dedicated this sort of
priority and effort to new space mission, it would be over funded and
launched by now.

As for Revolve vs. Rotate. Revolve may be the common and non-ambiguous
word, but the word rotate, is fine too, at least outside peer-reviewed
journals, unless the language police have gotten to it. In math, the origin
we choose to rotate does not have to be the spin axis. That is a special
case. I don't think there was any confusion in my use. I don't follow your
need for the relevance of that point other than as an attempted slap in the
face, though I appreciate the clarification anyway and will think twice in
the future about who might object and treat you with your terms.

Finally, I believe you either haven't understood my point on the centroid of
mass, or are confused with all of the issues surrounding this. Or maybe I
am, though I don't think so, and am a little too tired to draw the geometry.
Here's my thought process to make concrete which I had conceptualized for
you, right or wrong. Kepler's Laws allow for all orbits to be elliptical.
If the center of mass is the axis of rotation (revolution?), my intuition is
that the smaller body will not maintain equal distance from the larger at
all times. You can pull them further apart and the center of mass will
remain where it is...without worrying about staying "inside" the crust of
the larger body if the sizes are fairly similar as in the case of twin
planets. I am thinking of a see-saw with two water balloons on each side of
the fulcrum. The orbital energy comes into play but it is clear to me that
they can see-saw whether their surfaces intersect or not - ie, they can be
as close together or far apart as they wish with the appropriate energy.
The Sun is about 1000 times the mass of Jupiter. Jupiter is at about 5.2
AU. I believe that would put Jupiter OUTSIDE the photosphere of the
Sun....do you not think it would be a little arbitrary to decide the Sun was
a double star system just based on that alone? Because if Jupiter were in
Ceres place, it would be "inside" the Sun?

Perhaps the example is quite poor in that it mixes in a fulcrum, but I am
trying to address your question and a bit worn out from my observations of
Ceres last night and am not particularly looking to say more than I've
already argued on these points other than, as Jack Horkheimer might say,
"Keep Looking Up!" (and he wasn't thinking of the dictionary:)).
Best wishes and cloudless nights to you, Doug.



Larry wrote:
> Hi Doug:
>
> I am not an expert on dynamics, but the center of mass is the center of
mass.
>
> If you have two objects in orbit (revolve, not rotate) around the center
of
> mass, if one were larger, its orbit would have to be elliptical in order
for
> the center of mass to go outside to inside of it.
> We are not talking about multiple systems with liquid planets, that is
going a
> little too far. One body cannot go into and out of another.
>
> I do not understand your first P.D. That is a slap in the face of the
people on
> the committee as well as the organizations that recommended and picked
them.
> Are you more qualified to have chosen the committee?
>
> To answer your P.D.D., it would help to actually check your facts. The
name of
> the planet predates the dog by nearly a year. The kid is still alive and
was
> interviewed earlier this year, why not ask her?
>
> Larry
>
> Quoting MexicoDoug <MexicoDoug_at_aim.com>:
>
> > "> and the Charon aspect specifically for going too far in essentially
> > > recasting too many small round objects as full-fledged planets.
> > Eventually,
> > > with new discoveries, there would likely be hundreds."
> >
> > Hello Again, The Charon and the "rotating around center of mass outside
the
> > larger body (Pluto in this case)" criterion aspect is very unwieldy for
me.
> > If a soccer ball, or other object which could have melted and rounded
itself
> > (or even rubble-pile modeled asteroids) gets into a meta stable orbit
around
> > the center of mass of the multi-body system in the appropriate
conditions,
> > it will become a planet for the moments it rotates outside the other
members
> > crust. And more interestingly, if the orbit is of high enough
eccentricity,
> > the center of mass will vary inside and outside the major body. I guess
the
> > simple solution would be to refine the definition for convenience to say
> > that all bodies are compared as if they orbited the major body of the
system
> > at "X" distance, etc. But this innocent corollary is a needless
> > complication and goes against the grain of the intention: to make it a
> > fairly independent set of criteria based on a priori physics. There is
> > "based on physics" and "making reference to physics". Anyone can make
> > reference to physics - the IAU committees still hasn't understood that
> > though they've come a good way along. Ganymede and our Luna moons are
> > excluded based on what boils down to an arbitrary criterion. Time to
cut to
> > the Gordian chase and toss out this criterion. Anything else will smack
of
> > arbitrariness. How scientific can an issue be when you have near
50%-50%
> > acceptance/rejection after so many years of debate? I won't get going
on
> > "dwarf" status. With stars it has real meaning. However, it is
arbitrary
> > in its proposed use with the planets and again a cheap shot to put
> > pseudoscience masquerading as real science (unethically) by experts in
> > something who seems to feel that their diplomas make them experts in
> > applying well defined astronomical terms to an amorphous limbo. If you
want
> > to call it a dwarf planet - a double planet - any icy planet - a
terrestrial
> > planet - that's fine and highly context dependent. Thus the adjective
of
> > choice is in the domain of the speaker, not in the quaint streets of
Prague
> > in meetings as astronomers eat up the travel and entertainment bill.
> > Best wishes, Doug
>
>
> > P.D. The IAU Committee has utterly failed by not including a committee
> > member of the class and stature of Saul Kripke. Historians and
> > Astronomers...but how about including someone with real experience and
> > credentials in aprioricity who has danced with the likes of Kant (and
> > usually held his own). I trust they will remedy this, as good
scientists
> > not concerned about who shares their turf...
> > P.P.D. Pluto was actually named after the Disney Dog character by a
British
> > child, but was endorsed by astronomers under the auspices we generally
> > consider when explaining the logic of planetary nomenclature.
> >
> > ______________________________________________
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> >
>
>
> --
> Dr. Larry A. Lebofsky
> Senior Research Scientist
> Co-editor, Meteorite "If you give a man a fish,
> Lunar and Planetary Laboratory you feed him for a day.
> 1541 East University If you teach a man to fish,
> University of Arizona you feed him for a lifetime."
> Tucson, AZ 85721-0063 ~Chinese Proverb
> Phone: 520-621-6947
> FAX: 520-621-8364
> e-mail: lebofsky_at_lpl.arizona.edu
>
Received on Fri 18 Aug 2006 03:37:48 PM PDT