The Final IAU Resolution on the definition of "planet" ready for voting (Forwarded)

International Astronomical Union
Prague, Czech Republic

24 August 2006

The Final IAU Resolution on the definition of "planet" ready for voting

At the second session of the 2006 International Astronomical Union (IAU)
General Assembly, which will be held 14:00 Thursday 24 August, members of
the IAU will vote on the Resolutions presented below. There will be separate
sequential votes on Resolution 5A and Resolution 5B. Similarly, there will
be separate votes on Resolutions 6A and 6B.

Following active discussion among IAU scientists at the IAU 2006 General
Assembly in Prague, draft Resolution 6b (issued 16 August 2006) has been
updated and amended.

IAU President Ron Ekers says: "IAU's rules for proposing resolutions are
based on an open democratic process and it is a great pleasure for the IAU
Executive Committee to see the level of engagement of so many astronomers
here. We want to engage as broad a part of the IAU community as possible in
the decision-making process to give this Resolution the best chance to be
passed."

Below are the full texts of "IAU Resolution 5a for GA-XXVI", "IAU Resolution
5b for GA-XXVI" and "IAU Resolution 6a for GA-XXVI" and "IAU Resolution 6b
for GA-XXVI". The voting will take place in four steps.

The voting on these Resolutions is expected to end today (Thursday 24
August) between 15:30 and 16:00 CEST. This is a rough estimate.

According to the revised Statutes approved at the First Session of the
General Assembly last week, scientific issues such as Resolutions are
decided by majority of those IAU members present and voting at the business
meeting. Thus the scientific resolutions, including those on the definition
of solar system bodies, will be presented and decided by voting of the
individual members. Yellow ballots will be handed out to all IAU members at
the entrance. Members will vote by raising these ballots in the air; the
number of raised ballots will be counted. The result of the vote should be
known shortly thereafter and will be communicated in a public statement.

Notes for editors:

A press conference about the Closing Ceremony of the General Assembly,
including the results of the planet-definition vote, will be held at 18:00,
in Meeting Room 3.3 of the Prague Congress Center. (It will NOT be possible
for journalists to ring in to this conference: they must be there in
person.)

The panel for the press conference will be:

* Ron Ekers (outgoing IAU President)
* Catherine Cesarsky (incoming IAU President, Member of the Planet
Definition Committee)
* Jan Palous (Chair of the National Organising Committee)
* Richard Binzel (Member of the Planet Definition Committee)
* Karel van der Hucht (incoming Secretary General)

This press conference will conclude around 18:30 CEST.

The IAU is the international astronomical organisation that brings together
distinguished astronomers from all nations of the world. Its mission is to
promote and safeguard the science of astronomy in all its aspects through
international cooperation. Founded in 1919, the IAU is the world's largest
professional body for astronomers. The IAU General Assembly is held every
three years and is one of the largest and most diverse meetings on the
astronomical community's calendar.

Contacts:

Following the vote, some of the members of the planet definition committee
will be available for interviews (after the final vote):

Richard Binzel
Member of the Planet Definition Committee
Prague Conference Center, Meeting Room 3.1
Tel: +420-261-177-075


Junichi Watanabe
Member of the Planet Definition Committee
Prague Conference Center, Meeting Room 3.3
Tel: +420-261-177-081


Iwan Williams
President, IAU Division III Planetary Systems Sciences
Prague Conference Center, Meeting Room 244
Tel: +420-261-177-064


Owen Gingerich
Chair of the IAU Planet Definition Committee
Tel: via the Press Room +420-261-177-075

Professor Ron Ekers
IAU President
Tel: via the Press Room +420-261-177-075

Catherine Cesarsky
IAU President-Elect and member of the Planet Definition Committee
Tel: via the Press Room +420-261-177-075

PIO contact
Lars Lindberg Christensen
IAU Press Officer
IAU GA 2006 Press office, Meeting Room 3.2
Prague Congress Center
Tel: +420-261-177-075 / +420-261-222-130

Links:

* Programme for the Closing Ceremony
http://www.astronomy2006.com/second-...g-ceremony.php
* Live public webcast of the Closing Ceremony
http://astronomy2006.com/tv/
* The IAU Web page
http://www.iau.org
* IAU News during the 2006 General Assembly
http://www.iau2006.org
* IAU General Assembly
http://www.astronomy2006.com
* Free registration for the media
http://www.astronomy2006.com/media-accreditation.php

RESOLUTIONS

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 prototype. Resolution 6B introduces the name "plutonian objects" for
this class. The Merriam-Webster dictionary defines "plutonian" as:
Main Entry: plu.to.ni.an
Pronunciation: plu-'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.

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 a 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

[Footnote]

[1] The eight classical planets a 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."