The light from the exploding star reached Earth 320 years ago. The dead star's shredded remains are called Cassiopeia A, or 'Cas A' for short. Cas A is the youngest known supernova remnant in our Milky Way Galaxy and resides 10,000 light-years away in the constellation Cassiopeia, so the star actually blew up 10, 000 years before the light reached Earth in the late 1600s.
