The Universe consists of a billion, billion galaxies... 77,000,000,000 miles across, and every galaxy is made up of a billion, zillion stars and around these stars circle a billion planets, and of all of these planets the greenest and the pleasantest is the planet Earth, in the system of Sol, in the Galaxy known as the Milky Way ... And it was to this world that creatures of an alien planet came ... to conquer and destroy the very heart of civilization...