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.
The remains of the supernova was first detected by radio telescopes. It was often known as 3C 10, which is a radio-source designation, but now people call it Tycho's supernova remnant. It can be seen by light telescope.