Imagine a supermassive black hole that is millions or billions of miles across and is at the center of a rapidly spinning disk of super-hot gas. Around the disk and the black hole is a thick, doughnut-shaped torus of thicker, cooler gas. Matter falling toward the black hole accumulates in the torus and slowly swirls into the gas disk on its way to the black hole. Finally, right near the black hole, two super-energetic jets of matter shoot outward, above and below the disk, with matter traveling at nearly the speed of light. These jets extend thousands, even millions of light-years out into space. That is the basic picture of a quasar, or quasi-stellar object (QSO).