A star goes poof!

Explore the Night with Bob King

Seeking Cas A, the Ghostly Remains of a Mysterious Supernova

We still don't know for sure if anyone saw the supernova explosion in Cassiopeia around 1680, but there's no question we can observe what remains of it today.

Stellar Science

Quark Nova Spotted in Cas A?

Two elements deep within Cassiopeia A, hint the supernova remnant underwent a quark nova — a theoretical second explosion that leaves behind a quark star — just days after the original supernova.

Astronomy and Society

Cassiopeia A in 3D

Explore a supernova remnant with this fun interactive simulation, created from detailed space- and ground-based observations in multiple wavelengths.