Earth's Magnetic Field and Magnetosphere

Magnetism is one of the longest known physical phenomena and the Earth's magnetic field was one of the first scientifically studied aspects. The magnetic needle and its directional property is reported to have been discovered in China in the twenty-sixth century BCE; however, other reports give its introduction by Arabs or Europeans in the thirteenth century CE. Greek philosophers wrote about the mineral magnetite in about 800 BCE. Today, we understand how Earth's magnetic field is generated by the geodynamo process in its core. The interaction of Earth's magnetic field with the solar wind and the interplanetary magnetic field drives electric current systems in the ionosphere and magnetosphere. These have implications for technical and, in particular, communications infrastructure, spacecraft safety, and the health of space and aviation personnel. The sudy of rock magnetism showed that Earth's magnetic field has changed its orientation several times in the past and that. Paleomagnetic methods also laid the foundation for the development of plate tectonics, i.e. the continental drift since the geological past until today.