How Big Is Our Universe?
To conceive an actual picture of the size and magnitude of the universe is not possible for the human mind. We are unaware of its size. To imagine even, as to how big it might be, is quite hard.
We will see why this is so if we start and move out and away from the earth. The earth is a part of the solar system. The solar system is composed of the sun, the planets that revolve around it, the asteroids which are tiny planets, and the meteors. In comparison, the earth is a very small part of it.
This solar system is a tiny part of another large system. This bigger system is called “a galaxy”. A galaxy is composed of millions of stars. Some of these stars may be bigger than our sun. Each star may be an independent star system itself.
‘The milky way’, the stars in our galaxy are, actually, all suns. The distance that they are placed is so remote that it is measured in light-years and not in Kilometers. The distance traveled in a year by light is about 9600,000,000,000 kilometers. The bright star Alpha Centauri, nearest to the earth is about 40,000,000,000,000 Kilometres away.
This talk is only about our galaxy. The width of this galaxy is believed to be about 1,00,000 light-years. It amounts to 1,00,000 times or 9600,000,000,000 Kilometres. Thus the size of our galaxy is very small, as compared to the still larger system. There are, possibly, millions of galaxies beyond the Milky Way. All these galaxies are still only a part of some system.
This is how it is not possible to imagine even the size of our universe. Scientists believe that the universe is expanding. In other words, every few billion years the two galaxies will be twice as far from each other as they were before.