This is an illustration of the collapse of a massive star in which the large envelope forms a rotationally supported disk and may even lead to a relativistic jet. This "collapsar" picture may explain at least one class of gamma-ray bursts, cosmic explosions that are a million trillion times as bright as the sun! Gamma-ray bursts last for anywhere from a few milliseconds to several minutes, and for that time they are the brightest source of gamma-rays in the entire observable Universe. The energy from one event is enough to supply the entire world's electrical energy needs for approximately a hundred million billion billion years. Illustration by Tony Piro/Caltech