. >> reporter: professor mike massimino spent over 20 days in space and worked on the hubble telesco you looked at the planet, what did it look like? >> looks round, folks. it is round. my eyewitness account. and i looked at it as much as i could. it is round. >> okay, we're in the final countdown. how you doing over there? >> reporter: he's played himself on "the big bang theory." some flat earthers actually believe astronauts are just actors, part of a huge conspiracy going back to those first steps on the moon. >> it's one step for man, one giant leap for mankind. >> you don't believe they've gone to space? >> no, not at all. the rockets go up, there's nobody in them. >> i'm ready to speak fast -- >> reporter: rob is another cely flat earth movement taking clues from the bible's book of genesis. >> there's no way you can get a spinning helio centric globe out of anything in the bible. >> are you skeptical of everything? >> i've become skeptical of everything, rightfully so. >> pretty much earn here is kind of a conspiracy theorist. >> that's a common trait but there's a little bit