The universe, sometimes referred as space, is extremely large space. We all know this but, can not realize how large it is. We are like a small fish that lives in the pond water and can not imagine how big a ocean can be. Still, with our limited knowledge, we would try to get an idea about it.
As a basic information, we may know that, the universe, is (probably) endless space that has no center, left, right, up, down. It is just an endless space consist of endless number of galaxies . A galaxy is a group of billions of stars that looks like a whirlpool. Besides rotating, all the galaxies are moving far from each other and thus expanding the universe. Stars are giant ball of fire and have planets moving around them. Most planet have natural satellite rotating them. The sun is one of the billions stars of the galaxy named, Milky-way. Earth is a planet of sun and moon. Is a natural satellite of earth.
As the universe is extremely large, the unit for distance is “light year”. It refers to the distance that light can travel in one year. Light travels at a speed of about three hundred thousand kilometers per second. In a year it could be 9500 billion kilometers. A fast jet plane that can take us to another countries within a few hours, would take more than a million years to travel that distance. This distance is called light year.
As I mentioned above, it is difficult for us to realize how big it is. Just look at the above paragraph. When I said, 9500 billion kilometers, you understood it is very long distance. But you could realize how long it really is, only after you know that, it would take million years for a jet plane. To make ourselves understand the universe, we may try to make a very small, perfectly proportional model of the universe.
Let us start with the earth. In the model, the earth will be as small as a golf ball. We will have all the land, forests, roads, buildings on this model. But those are so small that we can not see any of those. Even, the great wall of China, Grand Canyon, tallest building on earth, all remain invisible. The golf ball sized model earth will look smooth and shinny even though the whole world is on it. There will be only one little rough spot on the surface of that earth model. That spot is, Mount Everest. In winter, when you blow of your breath on the ball, it makes a part the surface little moist. That is the total oceans on earth. I hope, you understand how small the model is.
Now, let us put the stars, and other planet in this model at proportional size and distance. The moon will be smaller than a piece of green peas and will be 110 meters away. The sun will be as big as a tennis court and will me 37 kilometers far from the golf ball sized earth. The farthest planet Pluto, will be 1850 kilometers away and travel around the tennis court sized sun maintaining average distance. The model is so small that we can not see the Mount Everest , Whereas in this same model, the solar system will be as big as the whole Europe. Now, let us start putting the stars. Do you know, where we will have to put the nearest star? I think it is beyond your imagination, We will have to put the nearest star on the moon, (almost half million kilometers away). Some stars may need to be put on other planets. We may need to put some stars outside of the real solar system. Some stars we have to put outside our galaxy. In this model, our galaxy milky-way will be million times bigger than the real solar system. In short, to accommodate that extremely small model of the universe, we need a space as big as the universe itself.
There is another easier way to understand. We all know atom, the smallest part of a matter. An atom is so small that you can put 200 of that on the sharp tip of a needle. Our earth is as smaller to the galaxy milky-way as one atom is smaller than the solar system. A galaxy contains as many stars as many sand grains a sea beach contains. The universe contains endless number of galaxies. Our galaxy Milky-way have billions of stars and the sun is one among them. The nearest star Alpha Centauri, is 4.5 light years away from the earth. If we can establish mobile phone, satellite communication with a planet of that star, (although it is never possible) then a live program on TV will take 4.5 years time to reach there on TV screen. If you talk on mobile phone your words will be hard 4.5 years after you have said and you will also hear the other person after the same amount of time. You will need 9 years to just say and hear “Hello” on phone. This is the situation of nearest star. Who dares to imagine about far stars ?
All stars are like our sun, a giant ball of fire. At the end of it’s life, before the fire goes off, a star lights up heavily for the last time. It makes a massive blast in the sky called, supernova. With our modern technology we can take pictures of some supernovas. The interesting part is, a supernova we see now, was happened hundred thousands, even million years. ago. They are so far that, light took million years to reach us. This makes us see an even that actually happened million years ago !! Light takes little more than a second to travel from moon to earth. From sun to earth it takes about 8 minutes. whereas light took million years to travel from that stars. It could make us have an idea about how far it is. Scientists believe that there are some stars who are so far that lights from them did not reach to earth yet. (in this 5 billion years age of earth)
You can not see the real shape of a building from its lounge or garage. You must step out of the building, go a few meters away and then look. at the building. Similarly, if we need to see how the universe looks, we need to travel a distance of 10 billion light years and then we will see a small part of the universe looks like the above picture.
SM Élite 
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