A black hole is a massive object whose gravitational field is so intense that no light (electromagnetic radiation) can escape it. Around many black holes is an accretion disk of material emitting energy as it falls into the black hole. This animation shows a cutaway of the accretion disk. The gap between the accretion disk and the black hole represents the innermost orbit matter can be in before plunging into the black hole. The radius of this innermost orbit depends on whether the black hole is rotating or not. If the black hole is rotating, material can orbit in more closely, causing the material to move faster than if the black hole is not rotating.