Site map . A black hole is a dense region of space believed to be the remnant of a collapsed star or clusters of stars or gas clouds. Black holes are thought to form when the hydrogen, helium and other fuel in the center of a star is used up, causing it to collapse from its own weight. Supermassive black holes have masses of one million to one billion Suns and are believed to have formed long ago from giant gas clouds or the collapse of clusters of many stars. A third class was discovered in April of 1999 and dubbed middleweights.
Scientists say that anything sucked into a black hole disappears from the observable universe.
Nothing, in fact, can escape from a black hole. A black hole is so powerful it even bends the light around it. Black holes come in different sizes. The entire mass of the Earth could be squeezed into a black hole the size of a marble. Scientists theorize about them by measuring their effects.