When a huge star runs out of fuel, it can no longer support its heavy weight and it begins to collapse. As pressure from the star’s hydrogen layers push down on it, it forces the star to become smaller and smaller. Eventually the star is compressed into a tiny space — even smaller than an atom — and a black hole is born.
A black hole is not really a hole and it is not empty. It is a huge amount of mass packed into a tiny space. This mass gives the black hole very strong gravity, which allows the black hole to gobble up anything that comes near it, including stars, gas and light.
A black hole’s gravity works a bit like a vacuum. If you have ever used a vacuum, you will notice that dirt, debris and crumbs begin to move toward the vacuum as it gets close to them. A black hole’s gravity works in a similar way. As objects get close to the black hole, its extremely strong gravity begins to pull the objects toward it.
The gravity inside a black hole is so strong that even light cannot escape. Light travels faster than anything we know (186,000 miles per second!). If light cannot escape a black hole, then we can predict that nothing else can either!