Matter | Pages 90-91

The Explosion Has Begun

Repulsive force between the nuclei overcomes gravity and the iron core rebounds. The explosive shock wave blasts through the layers, creating new heavy elements as it goes.

Seconds into the Explosion

Neutrinos trapped in the core stream out through the star's layers, driving the shock wave to blast off the star's outer layers. The neutrino burst is the first detectable sign of the star's demise.

Hours Later

The shock wave bursts through the star's outer surface, hurling into space several times the Sun's mass in heavy elements. The explosion leaves behind a neutron star, the original star's crushed core.

The nebula known as the Cygnus Loop (above) is actually the expanding shock wave from a supernova that exploded about 15,000 years ago. Colliding with a cloud of interstellar gas, the shock wave heated the gas, causing it to glow.