This was
your sky.

Cassiopeia A in a Million

This image of supernova remnant Cassiopeia A was constructed from one million seconds of X-ray data collected by the Chandra Observatory. It shows the expanding debris cloud from a star that exploded long ago. The outer green ring, about 10 light-years across, marks the shockwave from the original supernova. This detailed view helps astronomers explore the catastrophic end of massive stars.