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THE ASTRONOMER Electronic Circular No 2256      2006 Aug 25 13.10UT
Ed:Guy M Hurst, 16,Westminster Close, Kempshott Rise,  Basingstoke,
Hants, RG22 4PP,England.Telephone/FAX(01256)471074Int:+441256471074
INTERNET: GUY@TAHQ.DEMON.CO.UK      Backup: gmh@wdcc1.bnsc.rl.ac.uk
WORLD WIDE WEB                         http://www.theastronomer.org
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PLANETS
Judging from e-mails and telephone calls received, there has been 
considerable confusion in the Press/media regarding the outcome of the 
Resolutions passed at the IAU Assembly in Prague on 2006 August 24.

The following text is an extract from the Official IAU site and is 
repeated with no alterations:

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

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

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

The first members of the "dwarf planet" category are Ceres, Pluto and 
2003 UB313 (temporary name). More "dwarf planets" are expected to be 
announced by the IAU in the coming months and years

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

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

The full IAU announcement can be found at:

http://www.iau2006.org/mirror/www.iau.org/iau0603/index.html

Guy M Hurst