Supernova Remnant Cassiopeia A. Clock

The supernova remnant Cassiopeia A (Cas A), located 11,000 light-years from Earth in the constellation Cassiopeia. The image displays vivid colours and intricate structures. Cas A is the youngest known remnant from an exploding, massive star in our galaxy. On the remnant's exterior lie curtains of material appearing orange and red due to emission from warm dust. This marks where ejected material from the exploded star is ramming into surrounding circumstellar material.  Interior to this outer shell lie mottled filaments of bright pink studded with clumps and knots. This represents material from the star itself, and likely shines due to a mix of various heavy elements and dust emission. The stellar material can also be seen as fainter wisps near the cavity's interior. A loop represented in green extends across the right side of the central cavity.