It was not always known that the Milky Way is just one of many galaxies in the universe. Edwin Hubble is the man who discovered this startling idea and that the universe was expanding. As a result of these discoveries, Hubble became an international celebrity, and is remembered today as a genius of science.
An entertaining look into the man who proved there are other galaxies and the expansion of the universe. A little repetitive, but it was also written for emerging/intermediate readers so that makes sense.