神話に由来する名を持ち、太陽系の惑星の周りを公転する衛星。外洋で船舶の位置を特定するべく観測し、木星の衛星の食を利用して光速度を求めた歴史をはじめ、衛星の組成や構成、月が地球に、その他衛星が他の惑星に与える影響などを繙きます。多くの小惑星が衛星を持っていると考えられていることや、惑星系でも太陽系外惑星の衛星を見つけようとしている点にも言及します。
　　

• Introduces the reader to the moons of our Solar System, their discovery and naming
• Explains the nature and influence of our Moon
• Provides an up to date account detailing what we know about the nature and formation of other planets' moons from Voyager, Galileo, and other spacecraft

 
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.