Astronomers have determined that our universe is 13.7 billion years old. How exactly did they come to this precise conclusion? Tells the incredible story of how astronomers solved one of the most compelling mysteries in ...Astronomers have determined that our universe is 13.7 billion years old. How exactly did they come to this precise conclusion? 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.