Black hole, illustration. A black hole is an object (usually a collapsed star) so compact  that nothing can escape its gravitational pull. Not even light. On Earth an object needs to be launched with a speed of 11 kilometres per second if it is to escape the planet's gravity and go into orbit. But the escape velocity of a black hole exceeds the speed of light. Since nothing can travel faster than this ultimate speed, black holes suck in everything including light, which make them utterly dark and invisible. Stock Photo