An outstanding popularizer of science, an excellent storyteller, a passionate promoter of the cosmos, a visionary, Carl Sagan believes that the desire to wander and expand the boundaries of knowledge inherent in human nature and is associated with our survival as a species. In his sincere, fascinating book, philosophical reflections intertwine with enthusiastic descriptions of triumphant explorations of planets and moons, both involving human visitors to the moon and robotic missions. Acquainting us with our neighbors in space, Sagan not only enlightens and delights the reader, he also helps to understand how to protect the Earth.