Black hole,computer artwork. Planets,moons,stars,radiation and other matter are all spiralling into the black hole,dragged by immense gravitational forces. This will cause the material to give off high-energy X-rays. A black hole is formed when the core of a star collapses under its own weight,increasing its gravitational field to the point where,beyond a boundary known as the event horizon,nothing,not even light,can escape. This leads to its black appearance. Only sufficiently massive stars form black holes |