[meteorite-list] THE IAU PLANET DEFINITION -- IT'S MULTIPLE CHOICE!

From: Sterling K. Webb <sterling_k_webb_at_meteoritecentral.com>
Date: Thu Aug 24 03:15:35 2006
Message-ID: <00af01c6c74d$1271e0a0$4341e146_at_ATARIENGINE>

Hi,

    Despite the IAU declaration that there would be a single
Proposal and a single yes/no, guess what?

    It's a multiple-choice quiz!


>From The IAU GA - (Dissetatio Cum Nuncio Sidereo III, Page 8
http://astro.cas.cz/nuncius/nsiii_09.pdf
Retrieved 08/24/2006 2AM CDT
It has also just been posted at:
http://www.iau2006.org/mirror/www.iau.org/iau0602/index.html


Final Version of Resolution on the Definition of a Planet
At the second session of the General Assembly which
will be held 14:00 Thursday August 24 in the Congress Hall,
members of the IAU will vote on the resolutions presented here.
There will be separate sequential votes on Resolution 5A and Resolution 5B.
Similarly, there will be separate votes on Resolutions 6A and 6B.

Resolution 5A is the principal definition for the IAU usage of "planet"
and related terms. Resolution 5B adds the word "classical" to the
collective name of the eight planets Mercury through Neptune.
Resolution 6A creates for IAU usage a new class of objects,
for which Pluto is the proto-type. Resolution 6B introduces
the name "plutonian objects" for this class.

The Merriam-Webster dictionary defines "plutonian" as:
Main Entry: plu.to.ni.an - Pronunciation: pl?-'tO-nE-&n -
Function: adjective - Usage: often capitalized - : of, relating to,
or characteristic of Pluto or the lower world.

After having received inputs from many sides -- especially the
geological community -- the term "Pluton" is no longer being
considered.

Resolutions Committee members will be available at the IAU Exhibit
(situated in the exhibition area, 2nd floor of Congress Hall, Foyer 2)
from 13:00-13:30 today (Thursday). However, only minor corrections
can be accommodated at this stage. A French version of the Resolutions
will be available at the door.

IAU Resolution: Definition of a Planet in the Solar System

Contemporary observations are changing our understanding of
planetary systems, and it is important that our nomenclature for
objects reflect our current understanding. This applies, in particular,
to the designation 'planets'. The word 'planet' originally described
'wanderers' that were known only as moving lights in the sky.
Recent discoveries lead us to create a new definition, which we
can make using currently available scientific information.


Resolution 5A

The IAU therefore resolves that planets and
other bodies in our Solar System be defined
into three distinct categories in the following way:

(1) A planet[1] is a celestial body that

(a) is in orbit around the Sun,

(b) has sufficient mass for its self-gravity to overcome
rigid body forces so that it assumes a hydrostatic
equilibrium (nearly round) shape,
and

(c) has cleared the neighbourhood around its orbit.


(2) A dwarf planet is a celestial body that

(a) is in orbit around the Sun,

(b) has sufficient mass for its self-gravity to overcome
rigid body forces so that it assumes a hydrostatic
equilibrium (nearly round) shape[2],

(c) has not cleared the neighbourhood around its orbit,
and

(d) is not a satellite.


(3) All other objects[3] orbiting the Sun shall be referred to
collectively as "Small Solar System Bodies".

{Footnotes}
[1] The eight planets are: Mercury, Venus, Earth, Mars,
Jupiter, Saturn, Uranus, and Neptune.
[2] An IAU process will be established to assign borderline
objects into either dwarf planet and other categories.
[3] These currently include most of the Solar System asteroids,
most Trans-Neptunian Objects (TNOs), comets, and other
small bodies.


Resolution 5B

Insert the word "classical" before the word "planet"
in Resolution 5A, Section (1), and footnote 1. Thus reading:
(1) A classical planet[1] is a celestial body . . .
and
[1] The eight classical planets are: Mercury, Venus, Earth,
Mars, Jupiter, Saturn, Uranus, and Neptune.


IAU Resolution: Pluto

Resolution 6A
The IAU further resolves:
Pluto is a dwarf planet by the above definition and is
recognized as the prototype of a new category of
trans-Neptunian objects.

Resolution 6B
The following sentence is added to Resolution 6A:
This category is to be called "plutonian objects."
[1] An IAU process will be established to select a
name for this category
Received on Thu 24 Aug 2006 03:15:25 AM PDT