
Roughly 300 years ago, light from a supernova first appeared in Earth’s skies and formed the brilliant object Cassiopeia A. That blast emitted powerful shockwaves packed with clues about how a star unraveled.

Roughly 300 years ago, light from a supernova first appeared in Earth’s skies and formed the brilliant object Cassiopeia A. That blast emitted powerful shockwaves packed with clues about how a star unraveled.