Tycho Brahe's New Star

November 11, 1572

A Danish nobleman named Tycho Brahe noticed a brilliant new star in the constellation Cassiopeia that had not been there the night before. He measured its position meticulously and proved it lay far beyond the moon. The Aristotelian doctrine of unchanging heavens suffered its first mortal wound. The supernova, visible for sixteen months, challenged the Aristotelian principle of unchanging heavens, opening space for the Copernican revolution.