Black holes are basically objects in space which are invisible. The force of gravity present in a black hole is so strong that not even light can escape its pull. The gravity in a black hole is strong because it is a large mass, fitted into a tiny place. Scientists use special telescopes to locate a black hole. Scientists also locate black holes by the movement and behaviour of the masses around it. If stars or other masses are moving in a direction, then a black hole may exist there. Black holes exist in many sizes. There are very tiny ones and very large ones. The tiny ones can be as small as an atom while bigger ones can be so big that you can fit more than a million Suns in it. Different black holes have different masses. The black hole which is as small as an atom could have the mass of 10 or 100 or even maybe 1000 times the mass of the sun. Black holes can also have masses equal to million and billion times of the sun. When black holes suck matter inside them, they produce X-rays. X-rays cannot be seen by naked eye, so scientists use X-ray telescopes to detect X-rays. To escape the pull of a black hole you will have to travel faster than the speed of light as a black hole does not even let light escape from its pull. Black holes usually form when a star dies, though there are many other theories about black holes.
How is it formed?
When a star forms, it comprises of hydrogen. After its birth, every second that it spends of its life time, it converts hydrogen to helium. In this process of fusion, it produces more energy than it requires. As the star runs out of hydrogen it starts to convert the helium into carbon and then they start to convert carbon to oxygen. For stars of the mass of the sun, the reaction ends at oxygen, and then the star starts to cool down into a white dwarf and then a black dwarf. The mass and the force of gravity are balanced and no further reaction happens. But stars which have mass 5 times that of the sun, their story is a bit different. They continue the reaction process converting the oxygen to silicon, silicon to aluminium, the aluminium to potassium and so on until they reach iron. As iron atoms cannot be fused into anything further, the reaction stops for a second, and in that second, something very crazy happens. There is a huge explosion known as a supernova explosion, as in that second gravity wins. The core is converted into a denser object. The force of gravity of that dense object is so strong that not even light can pass through. Then black holes are formed. Black holes also form when dense objects such as neutron stars (which are also formed from super massive stars and then a supernova explosion. But black holes are formed from stars bigger than stars that form neutron stars) collide or bang.
The Event Horizon
The Event horizon of a black hole that disconnects the inside and the outside of the black hole. Light emitted from the inside of black hole can never reach an observer and an object falling into the black hole seems to take infinite time to reach the inside.
Scientists had detected gravitational waves by the merging of two black holes billions of light years away from the earth using LIGO (The Laser Interferometer Gravitational-Wave Observatory )
Written by: Mahatwa Kumar.
Mahatwa is a 7th grade student from India who is interested in Space. This short article is a self-composition of this super-passionate kid.