How big is the universe?
No one knows how big the universe really is. There are at least 100 billion galaxies that we know of. However, this number keeps growing as better telescopes are developed and we see more and more galaxies. On top of that, the galaxies are moving away from each other, causing the universe to expand. Some scientists believe that the universe will never stop expanding, while others think that one day it will begin to shrink until it becomes a fireball again.
