By Lara Owolabi
I’d always thought of a black hole as some sort of an endless void that sucks everything in and was never ending. So, I decided to do some actual research into what they are, how they’re formed and all the other interesting facts about them. With the trusty help of NASA, I discovered a lot about the incredible nature of black holes.
What even is a black hole?
Obviously, all black holes are in space; and I guess I was right about them being an endless void because gravity is so strong that light can’t even get out! A black hole may form when a star dies because it causes a big amount of matter to be forced into a tiny space, and since light can’t escape we’re not actually able to see them at all.
Very special space telescopes can sometimes help to find black holes by spotting stars that are close to black holes because these stars will behave differently from other stars; showing matter being drawn into the hole, and at times even tearing the star apart.
How do they form?
According to scientists, the smallest black holes may have formed when the universe began.
Stellar black holes form when a star essentially collapses into itself and this causes a supernova; an exploding star.
A supernova is an exploding star that blasts part of a star into space.
When it comes to supermassive black holes, ones that can be billions times bigger than our sun, we’re not really sure how they formed; but scientists say that they were just created at the same time as the galaxy they are in.
Stars can supposedly even be born from the materials that blast out from a supermassive black hole [Credit: ESO/M. Kornmesser]
How big are they?!
Black holes can either be big or small, and some scientists think that the smallest black hole could be as small as one atom! However, just because they’re small doesn’t mean they’re not powerful: it is said that they have the mass of a large mountain on earth, which is the amount of matter in an object. This implies they have a lot of stuff in them, especially supermassive blackholes.
One particular type of black hole is called ‘stellar’, a medium-sized black hole, and its mass can be up to 20 times more than the mass of the sun. Some scientists believe that there are lots of them in the Earth’s galaxy.
The biggest type of black holes are obviously called ‘supermassive’. The mass of these are at times that of one-million suns put together, and there is proof that every large galaxy has a supermassive black hole at the centre of it – even our own, in the Milky Way.
The black hole at the centre of the Milky Way is called Sagittarius A. It has a mass of up to 4 million suns and would fit into an area the size of our own sun.
How do scientists know they are there?
As mentioned before, a very special telescope has to be used in order to see a black hole, and since they’re ‘black’, essentially invisible, they can be quite hard to spot. However, the stars and gas around black holes act differently, so this is one way of knowing if they’re orbiting or flying around a black hole.
Scientists can see how the gravity of a black hole distorts space time [Credit: www.jpl.nasa.gov]
Plus, even though black holes are ‘black’, when they combine with a star they tend to create a high energy light that can be seen by special satellites and telescopes that indicate their presence.