Why would you listen to an astronomer about a planet?

I tell public audiences, don't go to a podiatrist for brain surgery; don't go to an astronomer for planetary science.

No one predicted Mercury would be a planetary core with the mantle stripped off. No one predicted volcanoes on the Jovian moons, or oceans on the inside of them. I can tell you, for every single planet, huge 'we never guessed that' things.

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

Not even Tombaugh and his mentors could have forecast how fascinating their new planet would turn out to be.

No one working as an astronomer is shackled in chains. This is a tremendous profession. There are lots of neat people, and you get to do cool things. If I had to say something negative, it's that there's often a whole lot of travel that takes me away from my children. That can be a bummer a lot of times.