The collapse of a star's core is like compressing a spring: matter falls inward, and a neutron star is born at the center. But the fall is never perfectly smooth. In the boiling outer layers, random eddies transfer angular momentum to the infalling gas, and a disk swirls around the central object.
This disk is no calm river. It pulses, strengthening and fading. Gas without rotation keeps falling onto it from above, yet the disk doesn't vanish. It's saved by internal friction, which redistributes angular momentum, like a spinning top that keeps going because it's constantly nudged from the edges. Meanwhile, powerful jets blasting along the axis clear a path through the infalling gas, and the disk lives even longer.
That's how the explosion is born — not as a uniform sphere, but as a dance of jets choreographed by the disk. This picture helps explain the full variety of supernova remnants, from symmetric bubbles to chaotic tangles. The mechanism, dubbed "jittering jets," is becoming a key to understanding the deaths of massive stars.
The neutron star left behind after the explosion squeezes the mass of the Sun into a sphere the size of a city — about 20 kilometers. A teaspoon of its material would weigh a billion tons.
In Arthur C. Clarke's novel Rendezvous with Rama, humans explore a mysterious object that resembles a supernova remnant, riddled with internal structures.