It's now, officially, a "plutonian object"
BBC reports that the resolution is passed.
ETA: They rejected resolution 5B, which means that a dwarf planet is not a type of planet, but a wholly different thing. So they've both redefined the solar system and the rules of grammar. Go IAU!
RESOLUTION 5AYou'd have thought that, during their biggest conference news in years, they'd manage to not schedule essential maintenence on their main website? Mirrors are fine, but the mirroe is way down the Google results for them.
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 planet1 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 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.RESOLUTION 5B
Insert the word "classical" before the word "planet" in Resolution 5A, Section (1), and footnote 1. Thus reading:
(1) A classical planet1 is a celestial body . . .
and
1The 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."
ETA: They rejected resolution 5B, which means that a dwarf planet is not a type of planet, but a wholly different thing. So they've both redefined the solar system and the rules of grammar. Go IAU!