The Exploring the Universe series is a detailed guide to the exploration of space, covering subjects from the birth of the universe and the formation of black holes to astronaut training and space telescopes. Each book includes clear explanations of scientific concepts and theories and informative annotated diagrams. There are around 2,500 visible stars in the night sky, but these are just the brightest of a multitude of stars of different types and ages. Most of those we can see with the naked eye are members of our local galaxy, the Milky Way, but this is just one of billions of galaxies in the known universe.