What are black holes made of

Black holes

Black holes are the strangest objects in the universe. A black hole has no surface like a planet or a star. On the other hand, it is an area in space where matter has collapsed into itself. This catastrophic collapse causes an enormous amount of mass to be concentrated in an incredibly tiny space. The attraction of this area is so strong that nothing can escape it - not even the light.

Black holes can't be seen, but we can identify them by how they affect neighboring nebulae, stars, and galaxies. Many are surrounded by disc-shaped accumulations of material. They swirl around the black holes like a vortex, becoming extremely hot and emitting X-rays.

Black holes come in a wide variety of sizes. Many are only a few times more massive than the sun. These black holes of "stellar mass" are formed when the life of a massive star that is about ten times heavier than the sun ends in a supernova explosion. What remains of the star - still many times the mass of the sun - collapses into a structure with a diameter of only a few kilometers.

In the center of most galaxies, like the Milky Way, there are supermassive black holes. These can be millions or billions of times the mass of the sun. Super-massive (also called supermassive) black holes also drive active galaxies and ancient galaxies called quasars. Quasars can be hundreds of times brighter than even the largest normal galaxy.

Objects falling into a black hole are literally stretched to the point of bursting. Let's say an astronaut dares to get too close and is pulled into a black hole - the incredibly strong force of gravity would just tear him apart.

Last modified 11 February 2011