Great question Starson. This is what is sometimes scary about science, that at one moment we will know and swear by something and the next minute it changes, this has happened numerous times through out scientific history! The only hope that I can give you, is that back then when people “assumed” the earth was flat (I say assume because they never actually KNEW this, they just assumed it because of the lack of technology, this is all they knew back then) they really never had any supporting data for this to be held up and never went through the strenuous processes that we go through now a days to prove a scientific theory. As far as the sun being the centre of the Universe, again, back then they never really had much more than very good assumptions to base their knowledge on. As science advances we develop much more thought out and tested ideas. In order to get a scientific theory passed in present day it will be neglected, denied, dismantled, reassembled and repeat 100 fold. I cannot say that this will never happen again, but I do have much more faith in scientists in this day and age then I did back then!