The Kuiper belt region, which I call the third zone because it lies beyond the rocky terrestrial planets and beyond the giant planets, is a bizarre frontier.

If you put Earth out beyond Neptune, you wouldn't be able to call it a planet because it couldn't clear its zone.

There are lots of really interesting little planets out there in the Kuiper Belt, but Pluto's the only one that's got all the cool attributes.

Just because Pluto orbits with many other dwarf planets doesn't change what it is, just as whether an object is a mountain or not doesn't depend on whether it's in a group or in isolation.

Pluto is just the brightest of the many objects in the Kuiper Belt. It's a fossil relic of the formation of our solar system.

I like the planets because they are real places that you can go to and send machines to. Faraway astronomy - galactic astronomy and extra-galactic astronomy - is really cool stuff, but to me, it's about destinations.