The universe is very large. Nobody knows how large. All we know is that it is a vast expanse of space. It contains all of the matter and energy that exists or that has ever existed. This includes all the stars, galaxies and planets -- including our solar system.
Some distant stars are millions of light years away. And even the nearest star to Earth -- other than the Sun -- is more than 4 light years away. That's a long, long way, since a light year is the distance that light can travel in one year -- and light travels at 186,000 miles per second. How does the solar system fit into this picture?
We'll tell you in a minute. But first we need to tell you about galaxies.