What happens in a Black hole?

Black hole at a Galaxy centre
Credit: : ESA V. Beckmann (NASA-GSFC)

Black holes are made when really big stars explode as a supernova. The collapse of the core of the star happens very quickly and all of the material in the core is squeezed into a really small space. Because there is a lot of material in such a small space, black holes have a really strong gravitational pull. This means that anything which gets close to them is pulled in. Once something falls into a black hole it can’t get back out – not even light. The more things fall into a black hole the bigger they become. The bigger they become the stronger the gravitational pull, and the more material falls in. Once material goes into a black hole it is gone forever – black holes do not move things forward or back in time.

Astronomers are still not sure how the really massive black holes which live in the centre of galaxies are made, but we think that it is from smaller black holes eating more and more material and slowly growing. Black holes can also collide with each other and become one much bigger black hole.

The pull of a black hole is really strong when you are close to the black hole, but as you get further away the gravitation pull drops off quickly. This means that you have to get quite close to a black hole before you are pulled into it. For a black hole the mass of our Sun an object would need to get within 1500km to get pulled in. As most of space is empty it’s actually quite rare of objects to fall into black holes. The closest black hole to the Earth is 9.5 thousand, million, million km away – much too far away to be a problem for us! If a person ever did get close enough to fall into a black hole it wouldn’t be a nice end. You would be squashed horizontally into a thin line, then you’d be pulled vertically from your toes to your head. Astronomers call this ‘spaghettification’!