The sun revolves around the earth - for more than 1500 years, this world view of the Greek astronomer Ptolemy was seen as an incontrovertible truth. It fit perfectly into the Christian worldview, in which the earth and God's creation were the center of the world. But in the Ptolemaic calendar, the date and the seasons diverged. The pope demanded a calendar reform. The astronomer and scholar Nicolaus Copernicus was also commissioned to do so. But Copernicus had long ago discovered something groundbreaking and revolutionary. Although it would set the calendar right, it threw the pious Christianity into a serious conflict: The earth revolves around the sun! A dangerous thought. Should he publicize his scientific calculations, or should he continue to hold to the Christian worldview?