Black hole. Conceptual computer artwork of a black hole, a region in space where the pull of gravity exceeds the velocity of light. It is only visible from the effects it has on its surroundings. Its intense gravity distorts the light passing nearby. This causes the double images of the surrounding stars. A black hole is formed when a sufficiently- massive star has used up the fuel that sustained its nuclear fires. The resulting loss of outwards heat pressure allows a catastrophic total collapse of the star under its own weight.