BLACK HOLE

           WHAT IS BLACK HOLE?          

Black Holes are the mysterious, strange and most fascinating object in the space. When wrapped space-time remains after the gravity object which made itself shrink at a point, where singularity present at the centre and presence of an event horizon at the outer edge, are known as Black Holes. They are very dense and they have a such strong gravitational attraction force that even the light cannot get out from it.

For instance: "Imagine a star having mass, 10 times more than the mass of sun and the star squeezed into a hemisphere approximately the diameter of Delhi. As a result the gravitational field becomes so strong nothing, not even a light can escape from it".
         In 17th century John Michell was the first person who coined the term black holes to whole the world. After him, In 1796 Pierre Simon described Black Holes in his book "THE SYSTEM OF WORLD". After that, most famously black holes were firstly predicted by the Einstein's theory of general relativity, which shows us if a massive star dies, it leaves a small dense remnant core behind itself. If the mass of that core is three times more than the mass of sun, the equation showed that the force of gravity overwhelms all the force and produce a Black Hole. 


   HOW BLACK HOLES ARE FORMED?

Scientists think that the smallest Black Holes formed when the universe began and super -massive black hole were made at the same time as the galaxy they are in. Stellar black holes are made when the centre of a big star collapses itself, this causes supernova.


   SIZE OF BLACK HOLES:

 A size of a black hole can be big or small. Stellar black hole is one kind of black hole, it's mass can be upto 20 times more than the mass of the sun. Most of the Stellar Black Holes, however, led the isolated lives and are impossible to detect. Scientist estimated that there are as many as ten million to a billion of black holes present in our Milky Way Galaxy alone. 
      The largest black holes are known as "Supermassive" black holes. They have the mass more than the mass of 10 million suns together. Scientists have proofs that the supermassive black hole is present in the centre of every galaxy. The supermassive black hole present in the centre of milky way is known as "Sagittarius A". It has mass equally to the mass of 4 million suns. Astronomers can detect them by watching their effect on nearby stars and gases. 

"Sagittarius A" black hole in the centre of the milky way galaxy

  Scientists think that the small black holes are as small as a size of an atom. These black holes are very small but their mass can be equal to the mass of a mountain.  
  Scientists believe that the big black holes could be form from the stellar black holes collisions. In December 2004, NASA telescope observes a flashes of light known as gamma ray burst. Chandra and NASA's Hubble space telescope later gave the reports and data led the astronomers to a conclusion that these explosion can only be happen when a black hole collide with a neutron star to form another black hole.
            There are some weird facts about black holes that are: 

1. If we fall into a black hole the strong gravitational force would stretches us like a noodle, and you are dead before reaching to the singularity. In 2012 there is a study published  in Journal Nature that the quantum effect act as a fire wall at the event horizon which gonna burn you instantly.
2. Most of us thinks that the black holes sucks everything but that is not true because suction is caused by pulling in a vacuum which the massive black hole is definitely not. Instead, object falls into the black holes just as they fall towards anything that exerts gravity like Earth.    
3. The first black hole is Cygnus X-1. There was a friendly bet between Hawking and fellow physicist Kip Thorne in 1974, Hawking said that the source was not a black hole but in 1990 Hawking conceded the defeat. 
4. If a star gets too close to a black hole, the star can be torn apart. 
5. Recently, the event horizon telescope gets the image of a black hole in M87 galaxy. This was a extraordinary efforts,requiring 2 years of research after getting the image. Next target of scientist may be to spot Sagittarius-A in the centre of our milky way galaxy.

   

   IMAGE OF BLACK HOLE IN M87 GALAXY

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