Book excerpt: Earth's Core: Geophysics of a Planet's Deepest Interior provides a multidisciplinary approach to Earth's core, including seismology, mineral physics, geomagnetism, and geodynamics. The book examines current observations, experiments, and theories; identifies outstanding research questions; and suggests future directions for study. With topics ranging from the structure of the core-mantle boundary region, to the chemical and physical properties of the core, the workings of the geodynamo, inner core seismology and dynamics, and core formation, this book offers a multidisciplinary perspective on what we know and what we know we have yet to discover. The book begins with the fundamental material and concepts in seismology, mineral physics, geomagnetism, and geodynamics, accessible from a wide range of backgrounds. The book then builds on this foundation to introduce current research, including observations, experiments, and theories. By identifying unsolved problems and promising routes to their solutions, the book is intended to motivate further research, making it a valuable resource both for students entering Earth and planetary sciences and for researchers in a particular subdiscipline who need to broaden their understanding. - Includes multidisciplinary observations constraining the composition and dynamics of the Earth's core - Concisely presents competing theories and arguments on the composition, state, and dynamics of the Earth's interior - Provides observational tests of various theories to enhance understanding - Serves as a valuable resource for researchers in deep earth geophysics, as well as many sub-disciplines, including seismology, geodynamics, geomagnetism, and mineral physics