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Introduction to Black Hole

  • Utsav Mishra
  • May 20, 2021
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We live in a universe too vast and full of mysteries. For a common man, the phenomena happening inside this universe may not matter that much but for the ones involved in the study of it, every slight change in the universe means a lot. This universe where we live when looked at through our naked eyes shows us a lot.


Who hasn’t looked at the night sky and wondered about all the things present there? We will find very few people who don’t like to get fascinated by the celestial objects visible to us in the night sky. 


The numerous stars, moon, those planets, everything seems so fascinatingly beautiful that we aren’t able to take our eyes off them. But to the surprise of everyone, this night sky we see, this planet we live on, the moon we see, and the stars that twinkle at us is even less significant than one rice grain in 100 kilograms of flour. 


The universe we live in is too vast to be confined in celestial bodies. Some things remain undiscovered even after the advancement of science and technology. The actual size of the universe remains undiscovered as we progress in science and technology with every passing second. 


But, there are some things that are discovered and have been explained to us from time to time. One such fascinating component of the universe is “BLACK HOLE”.


What is a black hole?


As the name suggests it to be, a black hole is an empty space. Before we talk about it any further, let us know what makes this empty space worth knowing about?


A black hole is a place in space, with a gravitational pull so strong that even light gets attracted to it and isn’t able to escape. This gravitational pull is the reason for a large mass squeezed into a small space. 


As light can’t escape black holes, they aren’t visible to us or can’t even be seen through a telescope. It’s just another black empty space in the universe that can attract anything which comes in its range.


First discovered black hole


The first black hole ever discovered was the CYGNUS X-1. It was discovered in 1964. 


It was discovered during a friendly banter between Stephen Hawking and his fellow scientist Kip Thorne. Hawking kept claiming that it is not a black hole but later it turned out to be one and he lost. 


Kip discovered the black hole within the Cygnus constellation present in the milky way. It was discovered when it sucked gas from a blue supergiant star revolving around it.


Later in 1967, American astronomer John Wheeler coined the term black hole, as we know it today. When we talk about discovering black holes, a question pops up again, asking us “how are black holes discovered when they are invisible?”


Now we proceed towards the formation of black hole and learn what makes it an object with such a huge gravitational pull? This is an unusual yet fascinating component of the universe.


Formation of black holes 


Usually, when a star is dying, a black hole is formed. According to scientists, the first black hole was formed at the beginning of this universe. That is considered as the smallest black hole ever formed. 


Black holes are usually formed when a star dies and falls upon itself. That means, when a star collapses in its own gravitational field and falls upon itself, it results in a supernova. 


A supernova is an exploding star, the pieces of which get scattered in space. This collapse of stars occurs when they have exhausted all their thermonuclear fluids which keep them alive. When the collapse occurs, the outer layers of a star are blown away resulting in the squeezing of its huge mass in a tiny space. This squeezing process continues to a point where it reaches zero volume. 


When a huge mass compresses itself to a point of zero volume, density becomes infinite. This is called the singularity. This tiny space with infinite density acquires an extremely high gravitational force, resulting in the formation of a black hole. 


This process takes a very very long time for a dying star to get converted into a huge black hole. This is why scientists believe that the formation of this universe might have begun with the creation of giant black holes just after the big bang.


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How are they discovered?


Black holes are invisible as they do not emit out even a ray of light that goes inside them. But still, scientists are able to find the presence of a black hole in space. This is done by studying the behavior of other celestial objects. 


Usually, a star showing unusual behavior or its gas getting lost show that they are orbiting around a black hole. By studying the star scientists find out the location of a black hole. 


High energy light is thrown out when a star and black hole are too close to each other. This light can’t be seen through naked eyes and therefore, telescopes are used to find the presence of a black hole.



Types of black hole


Black holes are of two types-


  • Stellar black holes


These are small black holes with a high gravitational pull that are formed by dying stars. In them, the stars as big as the sun get concentrated into a diameter of a small village resulting in immensely high gravitational pull. According to researchers, our galaxy contains a few hundred million stellar black holes.



  • Supermassive black holes


These black holes are of the same size as the big stars. Unlike stellar black holes, they are known to be present at the center of every galaxy. These empty spaces, almost invisible to our eyes, lie in this universe. But a question arises, “what do they do by being just present in the universe?”


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What do they do?


Black holes are known to gather dust and gases around them which are present in plenty in this universe. Sometimes they engulf rotating objects around them, be it an asteroid or a small star, as they keep on engulfing these, their size increases with time. 


Sometimes, stellar black holes become enormous in size just because of this. These black holes don’t suck the objects around, instead, objects fall just like free fall in the earth’s gravitational field.


As they said, the curiosity of a human mind knows no limits and keeps asking questions, one such common question is that “if the gravitational pull of a black hole is so strong, can it cause any danger to earth?”


The answer is quite simpler. Let’s learn how.



Can a black hole engulf earth?


Black holes don’t move around engulfing celestial bodies like this. Also, no black hole is even close to the solar system of earth, keeping it far away from any change in its gravitational pull.


Even if a giant black hole as big as the sun reaches the place of the sun, still there will be no harm to the earth. This is because the gravitational pull of the black hole will be the same as that of the sun.


Also, the sun isn’t big enough for a star to turn into a black hole. All this information takes us to the final thing. The conclusion on the existence of these black holes.




Black holes are present in a large amount in this universe. They are just another fascinating thing having a place in space. The universe and outer space are more undiscovered than they are discovered. Maybe, in the coming days, we will get to hear about the discovery of something new, something more unusual yet fascinating. 


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Recently, scientists unveiled the first image of a black hole. This image was taken through an event horizon telescope. The black hole was present in galaxy M-87.


As science continues to improve, sooner or later we will get to know more about these empty spaces in outer space with extremely high gravitational pull.

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