Some people have speculated that the geomagnetic field carries information somehow used by our organism. At present we don’t know how to read the code.
— Buryl Payne in The Body Magnetic, Edition 4, Chapter 6 (Magnetism and Magnetic Devices), (Santa Cruz, California: independently published, February 1990), p. 118.
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...illustrates the dynamical changes of the global magnetic field in the course of a disturbance: a temporary compression of the magnetosphere by enhanced flow of the solar wind is followed by a tailward stretching of the field lines. Eventually, the increase of the tail magnetic field results in a sudden collapse of the nightside field (a substorm) and a gradual recovery of the magnetosphere to its pre-storm configuration.
Image credit: Nikolai Tsyganenko - Modeling the Earth's Magnetosphere Using Spacecraft Magnetometer Data