Within the magnetopause, the boundary between the influence of the solar wind and embedded IMF of solar origin, the near-Earth environment is strongly influenced by the geomagnetic field. The geomagnetic field is due to a variety of sources, those within the Earth, those within the ionosphere, and those within the magnetosphere.
The Earth’s magnetic field is responsible for organizing the flow of ionized plasmas within most regions of the near-Earth environment. Hence, it determines the boundaries of distinct plasma regimes. The magnetic field is also used widely for attitude measurement and for important spacecraft sub-systems such as magneto-torquers.