For more than 70 years Pluto was counted as the ninth planet, an isolated but sentimental favorite at the end of the Solar System. But in recent years this little world has been at the center of a neighborhood dispute of cosmic proportions. Just what on Earth caused Pluto to be struck off as a planet? It now seems Pluto has company, and lots of it. And we have more in common with this distant realm than you may have ever imagined.
Richard Smith and Chris Thorburn