Geophysics is the physics of the Earth. It encompasses areas such as seismology, plate tectonics, gravity, and the Earth’s magnetic field, all of which give clues to both the structure and the working of the Earth. Geophysics: A Very Short Introduction describes the internal and external processes that affect the planet, as well as the techniques used by geophysicists to investigate them. It explains how analysis of the seismic waves produced in earthquakes reveals the Earth’s internal structure, and tells how heat is transported through its interior. Chapters describe how satellite missions measure the gravity and magnetic fields, and explain how its magnetic field shields the Earth against harmful radiation from the Sun and outer space.