Articles
Galaxy: An enchanting world full of mysteries…
By Ankita Mishra, Std. XI, Sai International School
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The word “galaxy” sets different perspectives in different minds. For some adventurous minds it might be James Gunn’s famous Guardians of Galaxy whereas for some curious minds it may be an extensive gravitational bound system of stars, stellar remnants, dust, and dark matter.
So, let me give you a brief description of what our galaxy, The Milky Way or the Akash Ganga is. It’s difficult to imagine even the most powerful object of our entire Solar System, the Sun, without the Galaxy. We all are born from the Galaxy. It’s interesting to know that all of us have little portions of star fire or galaxy in our complex human system.
Everyone of us has always imagined galaxies to be beautiful, and amazing with lots of twinkling stars and illuminating comets. Some even dream of travelling to galaxies. But, while dreaming , have you ever paused for a while and asked yourself , Where are we? What is our origin? Many of you will answer with a big NO. We human beings along with the other living and non-living elements of life are living in a galaxy. It forms the basis of any planetary system. For example-The food you eat, the water you drink, the television you watch, the books you read and anything, absolutely anything and everything is made up of star fire of the galaxies.
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What are galaxies?
Look around the universe and you will see galaxies of all kinds. A huge topical ray of unique shapes and sizes. These grand galactic structures fill the cosmos.
Galaxies of different colours, sizes and shapes
The basic building structure of the universe is galaxies and there are hundreds and billions of galaxies in the Universe.
The same way the cells make up the body or bricks make up a building , galaxies make up the universe . We should thank our lucky stars for the beautiful galaxies.
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Galaxies are the only space in the Universe where stars and planets are formed. We never find stars out of the galaxy. This is the only place where hydrogen is brought and heated up and a generation of life can begin. Even though there are many galaxies in our Universe, there is only one who gave birth to us…
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Our galaxy-The Milky Way
The Earth is our home. The Sun is our star and the Milky Way is our galaxy.
The Milky Way is unexplored; because we haven’t seen it from within, but only a band of stars stretched across the sky. The same galaxy when viewed from the space projects a different picture. It is a spectacular giant galaxy made up of 200 billion stars. Our Sun is just one star out of its enormous starry arms.
Our galaxy is very huge. It is actually one of the biggest galaxies in the Universe as a matter of fact. Massive! Magnificent! Our galaxy has long hidden secrets at its heart. The biggest mystery is:
Our galaxy-The Milky Way (as seen from space)
“How did it form?
Nothing ever happens by itself. Something needs to mix up and create something. According to scientists, the massive destroyer ,the black hole has its link with the creation of the huge galaxies.
So did the black holes form the Milky Way?
The Solar System, the planets, the cities, the towns, we ourselves were formed out of the newly born stable atoms and compounds. These wouldn’t have survived for long if galaxies did not exist.
But our galaxies originated from…it’s still a scientific mystery. To find a solution to this cosmic problem, we must travel back to infant Universe,
Aftermath of the Big Bang Theory
i.e. just after the Big Bang. 13.6 billion years ago there are no stars, no planets and no galaxies. The early universe is just a thick, uniform soup of gas with some tiny irregularities. But it is enough to set gravity into work and pull the gas together.
Gravity keeps on compressing the gas down to a point and that’s when temperatures rise dramatically to 50 to 100 million degrees. At this point, ignition is achieved and hydrogen fuses into helium and
A STAR IS BORN!
A picture showing the birth of a star. During the birth of a star a huge amount of cosmic radiation is evolved
In this theory, not only one but millions and millions of stars burst into life. Slowly gravity brings them together. After a few billion years, a rotating disc of star is formed and thus, a galaxy is born. So, maybe our galaxy – The Milky Way was formed like this. But there are some loopholes in this theory. There is a lot of gravity left out. Scientists in NASA discovered that the stars in the Milky Way seem to orbit like planets, around an invisible object which has a mass which is much more than the solar mass.
Till date there is no theory which can give us an exact picture about the formation of our galaxy.
So, the best theory which is believed to be true is :
The Milky Way was formed shortly after the Big Bang as one of the denser areas of mass distribution in the Universe. Compare this to a pudding with lumps in it, the lumps being the stuff the Universe emerged from. Some of these denser areas were globular clusters,
which contain older stars. These stars form the stellar halo. Within a few billion years of the formation of the first stars, the Milky Way had accumulated so much mass that it started to rotate more quickly. Due to the conservation of the amount of rotation, the gaseous interstellar medium collapsed from a near-spherical shape and changed to a flat disc. Thus, the newer stars, including the Sun, formed in this spiral disc.
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The galaxy formation process has not stopped as our universe is constantly evolving. The Milky Way has already swallowed several galaxies and is expected to collide with the nearest galaxy Andromeda in a few billion years. You can call the universe vast, beautiful, violent, but not cramped and small. It is a huge region filled with various cosmic mysteries which require the wildest of one’s imaginations to solve. Who said that the Universe is dead…It’s still living and most importantly it’s young and beautiful. Some parts of the Universe are still growing and expanding each and every minute. So, we, the “Earthians” have never seen what lies beyond the Milky Way. Discoveries say that there are more stars in the Universe than the water droplets in the Pacific Ocean. They may seem twinkling and small pretty structures to our eyes, but are actually a part of our galaxy, or may be some other galaxy or may be even a young galaxy churning in the vast cosmos.
-Ankita Mishra