Astronomers have determined that our universe is 13.7 billion years old. How exactly did they come to this precise conclusion? "How Old Is the Universe?" tells the incredible story of how astronomers solved one of the most compelling mysteries in science and, along the way, introduces readers to fundamental concepts and cutting-edge advances in modern astronomy. The age of our universe poses a deceptively simple question, and its answer carries profound implications for science, religion, and philosophy. David Weintraub traces the centuries-old quest by astronomers to fathom the secrets of the nighttime sky. Describing the achievements of the visionaries whose discoveries collectively unveiled a fundamental mystery, he shows how many independent lines of inquiry and much painstakingly gathered evidence, when fitted together like pieces in a cosmic puzzle, led to the long-sought answer. Astronomers don't believe the universe is 13.7 billion years old - they know it. You will too after reading this book. By focusing on one of the most crucial questions about the universe and challenging readers to understand the answer, Weintraub familiarizes readers with the ideas and phenomena at the heart of modern astronomy, including red giants and white dwarfs, Cepheid variable stars and supernovae, clusters of galaxies, gravitational lensing, dark matter, dark energy and the accelerating universe - and much more. Offering a unique historical approach to astronomy, "How Old Is the Universe?" sheds light on the inner workings of scientific inquiry and reveals how astronomers grapple with deep questions about the physical nature of our universe.