RESOLUTIONS
Resolution 5A is the principal definition for the IAU usage of "planet" and related terms.

Resolution 6A creates for IAU usage a new class of objects, for which Pluto is
the prototype. The IAU will set up a process to name these objects.

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,
except satellites, 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) shape2 , (c) has not
cleared the neighbourhood around its orbit, and (d) is not a satellite.

(3) All other objects3 except satellites orbiting the Sun shall be referred to
collectively as "Small Solar-System Bodies".


1The eight "planets" are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus,
and Neptune.

2An IAU process will be established to assign borderline objects into either
dwarf planet and other categories.

3These currently include most of the Solar System asteroids, most
Trans-Neptunian Objects (TNOs), comets, and other small bodies.


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.