In the night sky: Orion
In the night sky: Orion

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In the night sky: Orion

2.3.9 Black holes

A black hole may form when a massive star runs out of fuel causing it to collapse.

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DAVID MITCHELL:
60-Second Adventures in Astronomy. Number 12-- Black Holes.
DIY tip 34-- how do you make yourself a black hole? A black hole occurs when something has so much mass in such a small space that nothing can escape its gravitational pull, not even light.
In 1931, Subrahmanyan Chandrasekhar calculated that if a star is big enough, when it’s fuel runs out, there is nothing to stop gravity from its making core collapse to create a black hole. Unfortunately for Chandrasekhar, his contemporaries, like Sir Arthur Eddington, just didn’t believe him. But it turns out, he was right. And in 1983, he eventually won a Nobel prize for it.
So if a star is big enough to begin with, when it collapses it becomes so dense that its gravitational pull won’t let objects or light escape. In fact, you’d make a black hole if you crushed any object until it was small and dense enough. But you don’t always have to crush something to make a black hole. The bigger one is, the less dense it needs to be. So you could make one out of tap water, though the required amount will fill the space between the sun and Jupiter and sadly, there’s not enough water in the galaxy for that. So for you DIY enthusiasts, you’ll probably have to order it in specially.
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As the collapse continues, the core will become so dense that nothing, not even light, can escape the gravitational pull of the core. At this point, a black hole will have formed. Alternatively, if a single star is massive enough, the supernova explosion that forms the neutron star might not be able to release sufficient energy to eject all the outer layers of the star. That material will then fall back onto the newly-born neutron star, causing it to collapse to form a black hole.

Astronomers have found that black holes can have very strong magnetic fields which might be related to bright jets of radio signals from the black holes.

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