What is a Black Hole

The black hole is still a mystery. They can gulp many stars more than the size of a sun and still keep on eating a lot. Imagine a vacuum cleaner in your house which pulls all the dust and other littered things inside it. This can be a way to explain what is a black hole for kids but a black hole is an enigma which still needs a number of evidences and lots of research to be completely explored. The most relevant theory to explain the concept of black hole is the general theory of relativity given by Albert Einstein.

According to the general theory of relativity, a region or a body in the space which does not allow even light to pass through it is called a black hole. This is the simplest way to explain a black hole. Or we can say that the mass and the compactness of any object, curves the timespace. Although light travels in a straight line but due to the super strong gravity the light gets trapped in a black hole. This black hole is formed out of a dead massive star.

How Does a Black Hole Form?
To become a black hole, the star should be 15 times bigger than the sun. Here, death of a star means the end of the nuclear fuel as, in the life cycle of a star there is a continuous nuclear fusion reaction. When a star is dead its layer of hydrogen pulls it inside and the star begins to collapse in its own gravity. This makes the star smaller and smaller. Although the star keeps on decreasing in size its gravity keeps on increasing. Due to which there is a concentration of mass in a very small area which can be smaller than an atom. This body is known as a black hole because it does not allow even light to pass through it and as it does not reflect anything, it is invisible or can be considered as black.

Ss we know there is a continuous nuclear fission reaction inside a star and the end of the nuclear fuel results in the formation of a black hole, it may contain only neutrons but this is not certain. Till date, there is no evidence which justifies what is there inside a black hole. The outer part of the black hole is known as the event horizon or point of no return. It is said so because anything stuck inside the event horizon has no chance of coming out as it will require escape velocity which is greater than the velocity of light and which is an impossible phenomena till date. The center or the core point of a black hole is known as singularity. The density of singularity is huge as it may contain the mass of few hundred suns to many millions. Although the black hole is not visible, the x-rays it emits can be detected and the position of the black hole can be located.

Facts About Black Hole
Getting back to black holes, there are many things which are still untouched and unknown. Here are some of the facts which can throw a light on the mystery of black holes.

• There are millions of black holes in space. These black holes are so massive that they are supposed to hold the mass of more than a million suns. There is a super massive black hole in the middle of the milky way. This is approximately 30,000 light years away from the earth and is believed to have a mass of 4 million suns.
• A black hole does not allow even light to escape through it, this is because of the higher escape velocity of a black hole. It is higher than 186,000 miles per second, which is greater than light.
• Scientists detect a black hole by locating its X-rays. Black hole are excellent in emitting X-ray. EXIST is a spacecraft which is very useful in locating black holes. Apart from this there are many other spacecraft also which have helped in exploring the facts about a black hole. Some of them are XMM-Newton, LISA (Laser Interferometer Space Antenna) etc.
• 14 black holes have been found till date. Closest to the earth is V 4641 which is 1600 light years away and the second closest is Cygnus X-1 which is approximately 8000 light years away.
• The stars which are massive, i.e., 10 to 15 times more massive than sun, only end up as black holes and other smaller stars end up as white dwarfs or neutron stars.
• There are Stellar black holes and super massive black holes. Steller black hole is just one star which turns into a black hole whereas super massive black hole is made up of many small black holes. The number can be in millions or trillions.
• According to the general relativity theory it is believed that the time stops in the core of a black hole and the mass become infinite.
• Due to the high gravitational force, whatever is trapped in the black hole keeps on revolving at a very high-speed in the event horizon and because of the speed, it burns up and emit X-rays.
• Whatever goes inside a black hole never comes back. None of us know the depth of a black hole. It is believed to be infinite.

Many people wonder whether our sun will end up as black hole. So the fact is that our sun is not that much big to end up as a black hole. It will end up as a white dwarfs or neutron stars. But this scenario will come approximately after 5 billion years, so just chill and keep exploring some more amazing facts about the universe. The scientists are struggling up to solve this mystery and may be the next time when you search for black hole facts, you may come across some new interesting information.