Image credits: Dana Berry, Skyworks Digital/NASA
A black hole is a place in space where gravity pulls so strongly that not even light can escape from it. That’s why we can’t see them – though sometimes nearby gases and dust form a super-fast spinning disc around them, which we can see. Black holes are so powerful they can rip stars into atom-sized pieces and destroy whole solar systems! However, most black holes stay ‘quiet’, not eating anything. They appear when a huge amount of matter gets pressed into a tiny space. Anything could become a black hole if it was squeezed down small enough – even you. But it would take such an incredibly huge hug that it’ll never happen! So what does create them?
Stellar black holes are created when a huge star runs out of energy and collapses inwards. This causes a big explosion called a supernova. Then the star gets squashed into an incredibly tiny dot. There are also ‘supermassive’ black holes, found at the centre of galaxies, including our own galaxy, the Milky Way. They are about 20 billion times the size of our sun, and powerful enough to suck up a sun like ours every two days. We’re not sure how these form – you could say there’s a hole in our knowledge about them!
Image credits: X-ray: NASA/CXC/SAO/PSU/D. Burrows et al.; Optical: NASA/STScI; Millimeter: NRAO/AUI/NSF
Sometimes black holes crash into each other – and make an even bigger black hole!
Image credits: NASA
That’s where the sucking starts. It’s the hole’s point of no return, like when a swimmer gets pulled into a mighty waterfall, and it’s impossible to swim back to safety. We don’t know what would happen next, but one thing’s for sure: you could never come back, so you wouldn’t be able to tell us! Don’t even consider travelling into one of the smaller black holes. Its forces would probably stretch you spaghetti-thin, then crush you into nothingness before you even reached its event horizon!
A black hole pulls matter from blue star beside it. Credits: NASA/CXC/M.Weiss
No, so don’t panic! Black holes don’t travel around the universe eating planets. One could only affect us if it was very close to our solar system. And our sun can never become a black hole – it isn’t big enough.
Image Credit: NASA's Goddard Space Flight Center
Scientist Stephen Hawking thought we might be able to harness the power of black holes. He said that a mountain-sized black hole could provide all of our planet’s energy needs. But it would probably be thousands of years before we had the technology to tow a mini black hole into Earth’s orbit. Or maybe we’d have to create one somehow? Perhaps advanced alien civilisations are tapping the energy of black holes to fuel their worlds right now!
Enjoyed reading this feature? Find out more about the universe in issue 47, The Earth in the Universe.