We have the many layers of gases that surround our planet to thank for making Earth a habitable place. This instructive volume explains how Earth's atmosphere warms the planet, moderates its diurnal and nocturnal temperatures, and protects it from harmful rays. The book discusses how Earth's atmosphere evolved over time and presents the ways scientists have learned about these changes. Special attention is paid to the changes in the atmosphere that people have caused over the last two centuries, making this a very timely and topical read.