What Should We Ask Bill Nye?

mental_floss has the honor of interviewing Bill Nye next week. Nye is a Science Guy, inventor of a sundial aboard the Mars rovers (and other inventions), Executive Director of The Planetary Society, and avid swing dancer.
What would you like me to ask Bill Nye? I'll take questions in the comments through the end of Sunday, August 4. The most interesting questions (as judged by me) will make it in!
Thanks in advance for your questions. Let's talk science! (Tip: I'm definitely asking him about Mars, the ARKYD, and transportation. But I haven't written specific questions on those topics....)