no more pluto. first physicist to reclassify pluto he got hate mail from third graders who wanted to know what he had done with the planet they loved and who no one admits was the inspiration for the name of mickey's dog. turns out americans are weirdly intensely in love with pluto. it's sort of america's planet. it was the only planet discovered by an american. that was clyde tombaugh. 80 years ago, he made his own telescopes on the family farm. in the pluto files dr. tyson goes to a barbershop in the hometown of dr. tombaugh in streeter, illinois and finds out what he means to the town today. we're very proud of. very proud of him, what he did. >> and so you learned about him in high school? in elementary school? >> third grade, maybe. so his name comes up. and you learn he is a local guy. >> a streiter boy makes good. in third grade, wow. >> so you feel some pride? >> oh, you bet. always do. always here, that guy discovered pluto. >> walt disney named a dog after him. >> there you go. >> that's t

pluto has been demoted. >> correct. >> if you were over voting on pluto and whether it belonged in with the 3 others they were going to put in because pluto's size was comparable to the 3 others and they ought to get into this union too, how would you have voted? >> i would have voted the way the international astronomical delicacy voted. it was a wise decision. >> how would you have voted? >> the same way. it's bad to be tied up by historical artifacts so science can't progress into the future. >> so if -- that means we have 12 plan snets. >> no. >> you would voted against it. >> i would have voted there are 8 planets that are real planets. >> we can change -- we are really changing the planetary system, aren't we? by human will? and if we can do that in the instance of planets, can we do it elsewhere with regard to the universe? >> well, we're not changing the universe. all we're doing is talking about definitions, about words. and i think that the goal here is clarity. when pluto was discovered, it was a marvelous thing. new mexico deserves credit for having made an interesting disco

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