Pluto should be our ninth planet

More a discussion of technicalities than a technical discussion.

The contentious point is "has cleared its neighbouring region of ..."

But even the well-accepted "massive enough to be rounded by its own gravity", isn't well-defined there will always be inbetweeners. So planet is a word like other words to mean what people communicating agree it to mean and not a whole lot more. The 'not a star' is the technical part that can be scientifically categorized.