Black Holes

Black Holes are very, very weird. They are formed when very massive stars explode.

All of the star that is left by the explosion is crushed down into one single point.

Near to that point, the gravity is so strong that nothing can get away, not even light. This means that they cannot be seen directly - hence the name.

However, it is possible to see the effect of the black Hole on the stars and material around it. Gas, dust and other stars near to a Black Hole may be pulled in by the gravity and crash into each other, producing energy. Because this happens away from the centre of the Black Hole, the light can escape and we can observe it.

This image shows an artist's impression of the very centre of a galaxy where a large disk of gas is collecting. It is thought that a Black Hole right in the middle is gradually "eating up" the gas, and that the central brightness we see is the heat and light produced by spinning particles of gas colliding with each other as they approach the edge of the black hole.

Here we see another galaxy. The very bright middle is probably being lit up by stars being destroyed in the centre by a very big Black Hole. This type of galaxy is called a Quasar.