Universe

Anything can become a black hole, in theory.

The only difference between a black hole and our Sun is that the centre of a black hole is made of extremely dense material, which gives the black hole a strong gravitational field. It's that gravitational field that can trap everything, including light, which is why we can't see black holes.

You could theoretically turn anything into a black hole.

If you shrunk our Sun down to a size of only 3.7 miles (6 km) across, for example, then you would have compressed all of the mass in our sun down to an incredibly small space, making it extremely dense and also making a black hole. You could apply the same theory to Earth or to your own body.

But in reality, we only know of one way that can produce a black hole: the gravitational collapse of an extremely massive star that's 20 to 30 times more massive than our Sun.