Um..... um... what's the word... it's on the tip of my tongue... OH YEAH! Evidence. Got any?
(Btw, Galileo was not imprisoned for looking for exoplanets or aliens but for contradicting Church doctrine on geocentrism. Given the telescopes he was working with at the time, as they had only recently been invented, he wouldn't have found any exoplanets or aliens even if he were looking right at them. See )