In 1545 the Pope called an emergency summit in the Italian city of Trento. The idea was to deal with growing threats to the authority of the Catholic Church. Predictably a book on astronomy just published by a Polish priest was hardly noticed. But a century later the book had been banned, its teaching forbidden, and it had plunged the Church into crisis.When the dust finally settled, the universe was a different place. Because of that book and the events which followed we can explain the curved path of a cannon ball, say what time the sun will rise tomorrow, put men on the moon, and predict a heavenly visitation early in 1986...