Exploring Magnetism on Earth

Abstract:: This teacher's guide contains four lessons that provide a way for teachers to introduce students to and elaborate on Earth's changing magnetic field. This guide covers learning to navigate using Earth's magnetic field and compass, Earth's magnetic pole and its motion across Earth's surface, magnetic reversals on Earth, and Earth's currently declining magnetic field. These lessons have been taught primarily in math, geology, and astronomy classes.

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The Great Magnet, the Earth

Abstract:: This site provides a non-mathematical introduction to the magnetism of the Earth, the Sun, the planets and their environments, following a historical thread. In 1600, four hundred years ago William Gilbert, later physician to Queen Elizabeth I of England, published his great study of magnetism, "De Magnete"--"On the Magnet". It gave the first rational explanation to the mysterious ability of the compass needle to point north-south: the Earth itself was magnetic. "De Magnete" opened the era of modern physics and astronomy and started a century marked by the great achievements of Galileo, Kepler, Newton and others. This web site tells the story of Gilbert and his book--with glimpses of London in 1600, and with studies of magnetism before Gilbert. It then recounts the later history of the Earth's magnetism, including the remarkable discoveries of Halley, Coulomb, Oersted, Ampere and Gauss; the unexpected connection between sunspot activity and the Earth's magnetism; the deep-seated "'dynamo" believed to be responsible for the field; the strange reversals of the Earth's magnetic polarity; the role of magnetism in discovering the "drift" of continents; the extension of magnetism to space around Earth, even to other planets.

Abstract:: "This course introduces the structure, composition, and physical processes governing the terrestrial planets, including their formation and basic orbital properties. Topics include plate tectonics, earthquakes, seismic waves, rheology, impact cratering, gravity and magnetic fields, heat flux, thermal structure, mantle convection, deep interiors, planetary magnetism, and core dynamics. Suitable for majors and non-majors seeking general background in geophysics and planetary structure."