4.1 Dissecting the Universe

The Milky Way

Have you ever looked up in the night sky and seen the Milky Way? What you are seeing is actually just one of the spirals of our galaxy, the Milky Way.

So how do galaxies fit into the big picture? Let's say that each galaxy contains about 100 billion stars. The universe contains about 100 billion galaxies. That means that the universe contains about ten billion trillion stars! That's 10 000 000 000 000 000 000 000 stars!

This starts to give us an idea about how big the universe is. Remember also that between all of those stars is a huge amount of empty space. In fact, most of the universe consists of empty space.

Another way to think about it is this: there are more stars in the universe than there are grains of sand on all the beaches on Earth!