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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" 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 page goes on to list the eight planets:

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

Over the past 10 to 15 years, many astronomers assumed that one needed a Jupiter-like object in a stable near-circular orbit, preferably beyond a "life forming zone", before Earth-like objects could stay in the "life forming zone" long enough to form life. This new idea suggests that such Earth-like objects can arise where there are Jupiter-like objects orbiting very close to a star. If their idea is correct, then this means that a number of the stars with known "things-formerly-known-as-extra-solar-planets" containing a Hot Jupiter may also contain a stable Earth-like object in a "life forming zone".

I was writing my beef with the definition, then I realized it included "...is in orbit around the Sun...", rendering my point about the definition not working for extrasolar planets having odd orbits moot. So anyways, heres the link to the IAU press release:
IAU

A valid point, but you offer no counter evidence.

Anyway, here's a better link. The official site of IAU for 2006. Scroll almost to the bottom and you'll see, under "Resolution 5A":

(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.

Word for word as it is on wikipedia, glaring contradiction and all. It even has the British spelling of "neighbourhood".

Or were you worried about my definition of the word "satellite"? Find me a reputable astronomy site with a contradictory definition.

The International Astronomical Union has been the arbiter of planetary and satellite nomenclature since its inception in 1919. The world's astronomers, under the auspices of the IAU, have had official deliberations on a new definition for the word "planet" for nearly two years. IAU's top, the so-called Executive Committee, led by Ekers, formed a Planet Definition Committee (PDC) comprised by seven persons who were astronomers, writers, and historians with broad international representation. This group of seven convened in Paris in late June and early July 2006. They culminated the two year process by reaching a unanimous consensus for a proposed new definition of the word "planet."

Owen Gingerich, the Chair of the Planet Definition Committee says: "In July we had vigorous discussions of both the scientific and the cultural/historical issues, and on the second morning several members admitted that they had not slept well, worrying that we would not be able to reach a consensus. But by the end of a long day, the miracle had happened: we had reached a unanimous agreement." The IAU draft definition of "planet" and "plutons"

The International Astronomical Union has been the arbiter of planetary and satellite nomenclature since its inception in 1919. The world's astronomers, under the auspices of the IAU, have had official deliberations on a new definition for the word "planet" for nearly two years. IAU's top, the so-called Executive Committee, led by Ekers, formed a Planet Definition Committee (PDC) comprised by seven persons who were astronomers, writers, and historians with broad international representation. This group of seven convened in Paris in late June and early July 2006. They culminated the two year process by reaching a unanimous consensus for a proposed new definition of the word "planet."

Owen Gingerich, the Chair of the Planet Definition Committee says: "In July we had vigorous discussions of both the scientific and the cultural/historical issues, and on the second morning several members admitted that they had not slept well, worrying that we would not be able to reach a consensus. But by the end of a long day, the miracle had happened: we had reached a unanimous agreement." The IAU draft definition of "planet" and "plutons"

Did you guys not read about the barycenter of gravity? Read the AU's definition. http://www.iau2006.org/mirror/www.iau.org/NEWS.55. 0.html

The Earth-Moon isn't a double planet because the barycenter of gravity is clearly within the earth's surface because the size of the Earth is so much bigger than the Moon.

However, Pluto and Charon's barycenter of gravity is on the outside of Pluto's surface. That is why Pluto-Charon is a double planet, but not Earth-Moon. It's scientific, not arbitrary.

Here's the IAU web site draft definitions. Check out the artwork, including one "potato," 203 EL61.

Here's the IAU web site draft definitions. Check out the artwork, including one "potato," 203 EL61.