so many questions that each of us may ask and which he will find the answer in this book full of exciting details.
How big is the universe?
Nobody knows the dimensions with certainty. Our telescopes may not distinguish all of them. In addition ; astronomers are not sure that the light coming from the celestial bodies furthest away from the Universe arrives in a straight line: some celestial bodies may be closer than they seem to be … which may still want to say that they are 15.5 billion years-light of us.
What is a light year?
The distances between the stars are so huge that astronomers do not measure them in kilometers. They use light years instead. A light year; It is the distance traveled by the light in one year: it is about 9500 billion km.
Will the Universe disappear one day?
Nobody knows it. Perhaps it will continue to grow endlessly. Perhaps, then, will this expansion slow down or even stop? In this case the universe will begin to diminish; until all the galaxies collide with each other and destroy each other.
Is The Universe Growing?
Astronomers know how to measure the speed at which stars and galaxies move. Most of them are far from us, and the further they are; the more they seem to go fast. So the Universe is expanding