- Variations in the geomagnetic field have been measured in space as well as on the ground. Located in a geostationary orbit (at 6.6 Earth radii), GOES satellites observe geomagnetism from a geostationary orbit by using their installed geomagnetometer. Geomagnetic field values measured in the geostationary orbit stand at approximately 100nT when the satellite is on Earth’s dayside; however when it is over Earth’s night side it can drop to near 70nT. A disturbance of the geomagnetic field caused by solar activity drops the observed values of the geomagnetic field to near 50nT or less, and is the result of the geomagnetic field being weakened by magnetic field perturbations, which are created by intensified tail currents in the geomagnetic tail.
