How big is the universe?
Infinite, yet God holds it in the palm of His hand.
The universe is very large with an estimated radius of 46 billion light years. There are more than 100 billion galaxies that can be observed in the universe. Check out http://en.wikipedia.org/wiki/Universe#Size.2C_age.2C_contents.2C_structure.2C_and_laws for more details.
Nobody knows for sure because it's expanding so fast that some of its light will never reach us.
Unexplainably big ...i could go around it in 4 hours running and 5 if i jog