This was
your sky.

Cas A Supernova Remnant in X-Rays

Cassiopeia A, or Cas A, is a supernova remnant from a star that exploded 300 years ago. This Chandra Observatory image shows the complex shell in three X-ray colors, revealing unprecedented detail. The brightness, color, and position of the material indicate its origin within the star before the explosion. For example, bright knots on the left, with little iron, are thought to come from the star's outer layers.