What better way to understand the size of the universe than through our eyes. We are visual people and this website is absolutely amazing. There are more than 10 languages you can choose from. All you have to do is scroll to the left to see the world of the very tiny or scroll to the right to see the massive size of the stars to the beginning of time and space. I truly recommend it!
Here is the website: http://htwins.net/scale2/index.html