This is an account of the many ways in which the Sun affects our planet, how its influence has changed over the last few centuries and millennia, and the extent to which we can predict its future impact. The book is the first to integrate astronomical, geological, climatic and social aspects of the Sun. It includes a topical treatment of solar contribution to global warming, and demonstrates how wild and variable is the so-called Solar Constant. Our nearest star is a complex machine which needs to be treated with caution, and this book will equip every reader with the knowledge that is required to understand the benefits and dangers it can bring.