The Mystery of Black Holes

A black hole is one of the strangest objects in the universe. It is a region of space where gravity is so powerful that nothing can escape from it — not even light. Because no light comes out, a black hole is completely invisible, and scientists must study it in indirect ways. Most black holes form when a giant star runs out of fuel. Without the energy that once held it up, the star collapses under its own weight. Its material is squeezed into an incredibly small space, and the pull of gravity around it becomes enormous. The edge of a black hole is called the event horizon. Once anything crosses this boundary, there is no way back. For this reason, astronomers cannot see inside a black hole; they can only observe how it affects the stars and gas nearby. Surprisingly, black holes are not simply empty holes that swallow everything around them. Objects far away can orbit a black hole safely, just as planets orbit the Sun. Only material that comes very close is truly trapped. By watching this dramatic behaviour, scientists continue to learn about these mysterious giants.