“We have never seen them directly, yet we know
they are there lurking and dancing”
When we look at the sky most of us look at the shining stars which occupy little amount of space in the sky, but did you ever think of what’s there beyond these stars. Yes dark matter or dark energy which may exists in different forms and which may not be imaginable to human brains; all we know about it is its really vast and occupies most of the universe. Modern physics and astronomy has advanced so much that the discoveries made in the recent past go beyond the human thinking capacity and puzzle even the smartest minds on earth, one such startling discovery are the BLACK HOLES.
So why do we have to learn about these BLACK HOLES in the first place????
Yes these black holes are main cause of birth of new galaxies, new stars which in turn give birth to new planets and the composition with which the stars are made gives us the new heavier elements or may be earth might have been a consequence of this kind of phenomenon.
Back in the past, records show that ancient people looked at the sky in a different way than we do now-a-days, they used to treat stars as gods and some of them even designed their calendar’s based on the position of stars. Slowly, starting with the discovery of telescopes (thanks to Galileo) who made his first telescope and showed us a new way of looking at the sky and till the Hubble space telescope, each time they were shocked and amazed by the discoveries that were made by these time capsules, one of the most and the best discovery is again a black hole which may even swallow a star which is 100 or even 1000 times bigger than the mass of sun.
So first thing that comes to mind, what are these black holes, how and where they are found????
As the name refers BLACK HOLES are black in color (dark matter) which cannot be seen with our naked eye or even with the sophisticated technology ground telescopes we have.
Our universe is made up of trillions and trillions of galaxies some are pre-mature, some are old and some of them even disappeared (which were formed when at the time early universe). To know how galaxies are formed is whole another topic which I don’t want to talk about, and also it kind of deviates from the topic too.
As we all know that everything which is born has to die one day and same is the case with THE PLANETS, THE SUN, THE STARS which might occur over billions of years. Previously people used to believe that everything in the sky is totally still and remain same forever, which is totally wrong according to the modern physics and astronomy.
From the beginning of the BIG BANG till now which is estimated to be over 13 billion years, many stars might have born and died which have given birth to countless BLACK HOLES.
What really happens when a massive object like sun dies? But what really makes those massive monstrous objects to die??
We know that the only reaction happens in any star is FUSION. Yes it is. Lighter elements like Hydrogen atoms fuse together to form Helium atoms, these helium atoms again fuse together to form an other heavier element (carbon, silica etc.) till the heaviest element is formed that is IRON. Since Fe (Iron) is much heavier than the other elements, it tends to sink down to the center/core of the star (Sun). This process continuously happens for millions and millions of years.
Now there are two possibilities that might happen when a star dies, it might become a white dwarf star or a supernova explosion, which again depends on the size and weight of a star. We can roughly say that a star which is 10 times the solar mass (i.e., mass of the sun) will definitely undergo a supernova. Our sun would become a white dwarf after some millions of years.
Again there is no problem when a star becomes a dwarf star, because it doesn’t have much effect in its vicinity or to the other stars. The problem arises when stars undergo supernova and yes BLACK HOLES are the consequence of this massive supernova explosions.
As I’ve mentioned in the previous paragraph that due to the fusion process, heavier elements such as IRON sinks down to the core of the star, when enough IRON accumulates at the core, it begins to collapse under its own weight, that can send a shock wave racing outward literally blowing/ripping the star apart. At the moment when a star dies, if enough matter fall into its core it collapses into a point forming a black hole, beyond which nothing, not even light can escape. Guess what even a small dot(size of a small "Full stop" would weigh about 10 billion solar masses, that dense a black hole would be.
I have a small picture to show how a black hole looks like in the space, surrounding are the stars, dust, rocks and space debris which happens to be present from the previous explosions of stars. I hope you are there with me till now.
Now the new question arises again, where and how can we find these black holes, since they are black in color and even light can’t pass/escape through it, how we are going to find it??????
Yes, thanks to modern technology which made us look through the space and gaze at stars which are billions and billions of light years away from earth.
One question may pop up in your mind, does our own milky way has any black holes if so where are they located?????
As I’ve mentioned that black holes are the consequence of death of stars, yes our milky way which has billions of stars and some of them may have died and become black holes. Finding them in our own galaxy is challenging task to the astronomers. The reason behind saying that “its hard to find black hole in our own universe” is as follows
The above figure shows the location of earth in our Milky Way galaxy. As of now there is one black hole that is located at the center of our Milky Way and that’s how they knew that, this point is the center of the Milky Way galaxy. They found out this black hole using a star called Sagittarius A* which rotates around this black hole in its specified orbit, when this star moves close to this black hole its speed reaches around 3 million miles/hour.
How do I look and point them out, when they are black in color?????
Yes this has been puzzling many scientist’s around the world. But this is 21st century there is solution of almost everything. Now, definitely conventional mirror telescopes are ruled out because they cannot be seen into the deep space and they cannot escape the effects of space debris and disturbances from our own atmospheric conditions. So for this they have built a special kind of telescope called A Gamma-ray telescope and placed it in the LEO (low earth orbit) in order to cancel the disturbances produced by earth’s atmosphere. These telescopes could pierce through the space debris and can detect gamma ray emissions even billions of light years away. I don’t want to go into the technicality of how it works that deviates the topic we have chosen.
So what makes these BLACK HOLES visible??????
Astronomers looked in to the deep space and focused on an object known as QSRS (Quasi Stellar Radio Source) which offered a stunning surprise, a tiny region in its center is so bright that astronomers believe that the light is coming from a single object which is as massive as 1 billion solar masses. Inside this brilliant beacon space suddenly turns dark as it is literally swallowed by a giant black hole. Mean while scientists focused their search on a spiral galaxy called M87 which is 50 million light years away from the earth. They tracked gas flipping around center figuring its speed of around 3 million miles/hour which led them to calculate the mass of whatever occupied the center which was found to be 6 billion times the mass of sun. Scientists believe this point to be the galactic center of the universe, if it is the galactic center they have to prove that it is confined to really small volume (when taking in space proportions) and whip stars away in to space at great velocities.
Before going further we need to know something called as “EVENT HORIZON” which means “point of no return” in lay man terms. When these black holes are formed they get the massive spinning energy from the gravitational force. These black holes spin at unimaginable speeds preying on stars, space debris and everything that comes its way. So as seen from greater distances stars, space debris spin around these massive black holes as seen from the above picture. When the stars come to a point of “event horizon” they are gushed/sucked into the black hole and these stars are ripped apart into tiny particles which are blown away into to the space in opposite directions of the hole because of massive gravitational pull inside the massive BLACK HOLE as seen from the picture. This gushed matter in the space which is formed from the black holes emit large amounts of gamma-radiation, this is one way of finding the presence of black holes.
Some of the massive black holes which are born of the supernova of a star sized 10 billion times the mass of sun has a massive effect on the galaxy. It’s also seen that these massive black holes from different galaxies which spin and travel at greater speeds collide with each other ripping away everything that comes in its way and give birth to new life.
Do we have a threat with these black holes?????
Yes but not now, it’s in the near future may be after a few millions of years. Our neighbor galaxy called as ANDROMEDA galaxy which is just 2.5 million light years away is gushing towards the milky way and the same thing might happen to the two galaxies, the effect would be so massive that might rip of billions of stars and planets and at the same time give birth to new stars and planets and may be new us!!!!
