Proving to be both varied and fascinating, moons are far more common than planets in our Solar System. Our own Moon has had a profound influence on Earth, not only through tidal effects, but even on the behaviour of some marine animals. Many remarkable things have been discovered about the moons of the giant outer planets from Voyager, Galileo, Cassini, and other spacecraft. Scientists have glimpsed volcanic activity on Io, found oceans of water on Titan, and captured photos of icy geysers bursting from Enceladus. It looks likely that microbial life beyond the Earth may be discovered on a moon rather than a planet. In this Very Short Introduction David Rothery introduces the reader to the moons of our Solar System, beginning with the early discoveries of Galileo and others, describing their variety of mostly mythological names, and the early use of Jupiter's moons to establish position at sea and to estimate the speed of light. Rothery discusses the structure, formation, and influence of our Moon, and those of the other planets, and ends with the recent discovery of moons orbiting asteroids, whilst looking forward to the possibility of finding moons of exoplanets in planetary systems far beyond our own. ABOUT THE SERIES: The Very Short Introductions series from Oxford University Press contains hundreds of titles in almost every subject area. These pocket-sized books are the perfect way to get ahead in a new subject quickly. Our expert authors combine facts, analysis, perspective, new ideas, and enthusiasm to make interesting and challenging topics highly readable.