Thirty years ago the only planets we knew were the ones orbiting our own sun; we now know of thousands of other worlds orbiting distant stars. In this book astronomer Niall Deacon journeys to twenty of these globes: from giant, blisteringly hot planets orbiting close to their parent stars to frozen planets that float through space alone, and from dead stars shredding asteroids to worlds made of diamond and even planets that may be similar to the Earth. Deacon also takes in the latest exoplanet discoveries, and explains how astronomers have come to learn so much about these strange and distant worlds. Twenty Worlds tells a sweeping story, of real planets around other stars, and appeals to the wide audience for popular science and astronomy.