All about Cosmos

When we look into sky the question one must get in the mind is "how big is this cosmos ? " 

Frankly nobody knows how big it is . Several scientific theories exists who guesses about origin of universe and its expansion. 

Image :- Pexels.com

One can't talk about something which we don't know but we can surely talk about the observable universe from earth.The observable universe is a spherical region of the universe comprising all matter that can be observed from Earth or its space based telescopes and exploratory probes at the present time, because the electromagnetic radiation from these objects has had time to reach the Solar System and Earth since the beginning of the cosmological expansion.

    There are 2 trillion galaxies exists in observable universe. The word observable doesn't mean the capability of modern technology to detect light but it is physical limit created by speed of light itself. 

For human to its really hard to even imagine how big it is and number will be just on paper. 

There are probably billions of galaxies out beyond the Milky Way. And perhaps all these galaxies put together are still only a part of some larger system! So you see why it is impossible for us to have an idea of the size of the universe. Incidentally, it is believed by scientists that the universe is expanding. This means that every few billion years two galaxies will find themselves twice as far apart as they were before.