Just when we thought defending the old solar system was big and expensive enough, scientists have defined three additional objects out there as planets. The Plutonians (a dog-loving people) will be glad to know that they are pretty much officially recognized as occupying a sovereign planet now, and not just some super-cold chunk of rock on the fringe of the solar system. But troubles may still be ahead. Charon, formerly a satellite colony and mere dump station for Pluto, can legitimately claim it is no longer just a doggy service department, declare political independence, and get on with the process of diversifying industry. Analysts are observing the long-range implications with interest.