People all over the planet knew the earth was round thousands of years ago, the spanish and portuguese never thought it was flat, just smaller. The greeks proved round earth with sticks in a desert casting shadows of different length and angle, the eastern world simply observed the earth curving away more drastically the higher up you go and the fact that the oceans don't drain off the edge. Heliocentrism was heresy because the church had a hard on for didactic control of thought and no basis for the alternative beyond the word of some post biblical era saint's musings.