A planet orbits a star, has enough mass that it's mostly spherical, and is large enough that it's cleared its orbit.
I've received a number of emails and IMs asking me what I think of this definition and what it means for Pluto. My answer is that I love it. No because it demotes Pluto (though that doesn't bother me one bit.) I love it because millions of people all across this jumpin' green sphere are reading about and talking about astronomy and that can only be good.
