Supernova. Artwork of a supernova explosion with grid lines representing space-time. A supernova is the result of a massive star exhausting its fuel. All the hydrogen and helium has been fused to form heavier elements. Silicon fusion takes over and creates iron. Further nuclear fusion requires an energy input which destabilises the star. In less than one second, the core collapses. A rebounding shock wave from the super-dense core blows off the outer layers of the star (as seen) at thousands of kilometres per second. A supernova may briefly outshine an entire galaxy. If the core is massive enough, it forms a black hole, warping space-time.