Everything in space appears to be orbiting something. Moons orbit planets and planets orbit superstars. But what are all these superstars circling around? The answer:
Extremely strong objects called black holes. Black holes are areas in space that have such powerful gravity that they create a warp through space and time. They are dense, compact objects with such a powerful gravitational pull, under the classical concept of general relativity, nothing can escape from them, not even light. What occurs after a black hole has pulled matter into it has been theorised but is otherwise is entirely unknown.
The event horizon of a black hole is the boundary between its ‘outside’ and its ‘inside’. Close to a black hole, the slowing of time is extreme. From the viewpoint of an observer outside the black hole, time stops. For example, an object falling into the hole would appear frozen in time at the edge of the hole.
It is believed that black holes of stellar bodies are created when extremely large stars collapse near the end of their evolutionary process. After the dark hole has formed, it will continue to grow by absorbing matter from its surroundings. By absorbing different stars and colliding with other black holes, supermassive black holes of billions of solar masses are created. There is common agreement that supermassive black holes exist at the centres of most galaxies. There is even one at the centre of the Milky Way!