Das IAU Komitee präsentierte heute in Prag die neuen Vorschläge zur Planeten-Definition

Update 24. 8.: Endgültige Version der IAU Resolution ist jetzt online!
Final Version of Resolution on the Definition of a Planet
IAU Resolution: Definition of a Planet in the Solar System
Dissertatio cum Nuncio Sidereo III, No. 9 - August 24, 2006, Seite 8

Update: 23. 8.: Resolution 5 Entwurf c

Hier der Text der heute vor der Diskussion und Information ausgeteilt wurde.

Die abschließende Testabstimmung brachte folgendes Ergebnis:

RES 5: 70% Nein
RES 6: 80% Nein
RES 7: 80% Nein

Contemporary observations are changing our understanding of planetary systems, and it is important that our nomenclature for objects reflects 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. (Here we are not concerned with the upper boundary between 'planet' and 'star', nor the distinction between stars and brown dwarfs).

RESOLUTION 5 (draft)

The IAU therefore resolves that planets and other bodies in the planetary systems be defined in the following way:

(1) A planet is a celestial body that (a) has sufficient mass for its self- gravity to overcome rigid body forces so that is assumes a hydrostatic equilibrium (nearly round) shape[1], and (b) is in orbit around a star, and is neither a star or a satellite of a planet.

(2) In our Solar System we distinguish between the eight "classical planets", as the dominant objects in their local population zones, and "dwarf planets", which are not.

(3) All natural non-planet objects orbiting the Sun, currently includind most of the Solar System asteroids, near-Earth objects (NEOs), Mars-, Jupiter-, Neptune-Trojan asteroids, most Centaurs, most Trans-Neptunian Objects (TNOs), and comets, shall be referred to collectively as "Small Solar System Bodies". In the new nomenclature the term "minor planet" is not used.

[1] This generally applies to objects with mass above 5 x 10^20 kg and diameter greater than 800 km. An IAU process will be established to evaluate planet candidates near this boundary.

RESOLUTION 6 (draft)

The IAU further resolves:

Pluto is a dwarf planet by the above scientific definition, as are one or more recently discovered large trans-Neptunian objects. In contrast to the classical planets, these objects have orbital periods in excess of 200 years and typically have highlx inclined orbits with large eccentricities. We designate this category of planetary objects, of which Pluto is the prototype, as a new class that we call 'XXXXX'. We propose that the MPC create an new and separate catalog for these objects and their orbital characteristics, with Pluto as the first entry.

Where, XXXXX =          Or, ...

plutons                     Tombaugh Objects

plutoids                    Tombaugh Planets

plutonids                   plutians

plutonoids

plutinos (already used)

RESOLUTION 7 (draft)

The IAU further resolves:

For two or more objects comprising a multiple object system, the primary object is designated a planet if it independently satiesfies the definition of a planet. As secondary object satiesfying these conditions is also designated a planet if over most of the orbital period the system's center of gravity resided outside the primary. Secondary objects not satiesfying these criteria are satellites.

Vorschlag für neue Planeten - Definition der IAU


22. August 2006/Günther Wuchterl
Verein Kuffner-Sternwarte