Tycho's Supernova also called SN 1572 or B Cassiopeiae (B Cas) – was a supernova of Type Ia in the constellation Cassiopeia. It is one of eight supernovae visible to the naked eye in historical records. It appeared in early November 1572 and was independently discovered by many people. It is called Tycho's because Tycho Brahe published a book the next year about what he and other astronomers saw.