"gives planetary status to boring rocks like Mercury but denies it to fascinating worlds like Titan. It also denies planethood to any potential rogue planets. The most all-inclusive definition, which is favoured by astronomers like Mark Buie, is that a planet is anything big enough to be round but not big enough to fuse hydrogen. This would basically mean that any object discovered in the universe from about a fifth the mass of our Moon to about 13 times the size of Jupiter is a planet. It would mean that kids would have to give up learning the planets in our Solar System, since the number would go from eight to about 50. And that is the main issue. The word ""planet"" is not a scientific term; it's a term tied to myth, history and religion. It's ""special"". Is it right that tiny bits of ice at the end of the Solar System  should be so ""honoured"", or should the term ""planet"" be selectively bestowed only on those that ""deserve it""? This isn't a scientific issue, but then ""planet"" has never been a scientific word.   

 ::That's actually a pretty good definition, but I think you should add (or at least state more explicitly) that planets have to orbit the sun directly (i.e., a planet is not a satellite). This is not about how ""interesting"" something is. Britney Spears is ""interesting"", but she does not fit the definition I have made for ""music that I like to listen to"". Another good addition, I believe, would be to mention that planets must be ""unique"", that is, there should not be an abundance of like objects (think: Kupier belt) in the immediate vicinity. And finally, if the definition of a planet is not a scientific issue, then the IAU (a scientific organization) should leave the definition to people in linguistics, like the Oxford English Dictionary.    
 :::Your definition is basically the one the IAU chose to adopt. As for why they did it in the first place, they didn't have a choice. They kept under the rug for as long as they could; then Eris turned up and everything went crazy. Believe me, they didn't want to do it; Eris forced their hand.   
 ::::You're right, but I think the IAU should have worded the definition differently. ""Cleared the neighborhood"" is a little ambiguous. One of the articles dealing with this controversy mentions that Earth, Jupiter, etc. have not cleared their neighborhoods either, but the phrase actually refers to the original creation process. ""Unique"", in my opinion, is a bit less ambiguous/open for interpretation.    
 :::::I'm moving this here, since it really doesn't belong on the article's talk page. ""Unique"" isn't really any less ambiguous than ""clearing the neighborhood"". No planet is truly unique; each shares its orbit with dust particles, micrometeoroids, the occasional comet and many other things. If you read the clearing the neighborhood article, you'll see that Steven Soter has developed a perfectly acceptable mathematical definition for clearing the neighborhood that creates a sharp division between the large and small objects in the Solar System.   
 ::::::That's what I meant. The ""mathematical"" definition is less easily definable in layman's terms than ""unique"" as in ""no objects resembling it in the immediate vicinity"".    
 :::::::Resembling it how?   
 ::::::::In size, shape, and composition. For instance Pluto resembles Kupier belt objects, but Earth does not resemble Venus. And what I meant when I said that the IAU should have worded their definition differently was that to someone who had not heard of the mathematical formula or read the article, ""Clearing the neighborhood"" could have referred to the present, or the time of formation.    
 :::::::::Earth and Venus resemble each other rath