Book excerpt: For the general public, magnetism often seems more the province of new age quacks, movie mad scientists, and grade-school teachers than an area of actual, ongoing scientific inquiry. But as Ronald T. Merrill reveals in Our Magnetic Earth, geomagnetism really is an enduring, vibrant area of science, one that offers answers to some of the biggest questions about our planet’s past—and maybe even its future. In a clear and careful fashion, he lays out the physics of geomagnetism and magnetic fields, then goes on to explain how Earth’s magnetic field provides crucial evidence for our understanding of continental drift and plate tectonics; how and why animals, ranging from bacteria to mammals, sense and use the magnetic field; how changes in climate over eons can be studied through variations in the magnetic field in rocks; and much more. Throughout, Merrill peppers his scientific account with bizarre anecdotes and fascinating details, from levitating pizzas to Moon missions to blackmailing KGB agents—a reminder that real science can at times be stranger, and more amusing, than fiction. A winning primer for anyone who has ever struggled with a compass or admired a ragged V of migrating geese, Our Magnetic Earth demonstrates that education and entertainment need not be polar opposites.