"The Body Electric"
(Not as previously thought, by the earth's spinning core of molten iron). It serves to deflect most of the solar wind, whose charged particles would otherwise strip away the ozone layer that protects the Earth from harmful ultraviolet radiation.
The Earth's geomagnetic field strength is extremely stable. Averaging about 0.5 gauss. (a measure of the response of a medium to the presence of a magnetic field). Its daily change in strength is less than 0.1 gauss, which compared with the 200-gauss strength of the magnet that holds your refrigerator door closed, seems negligible.
About 10% of the surface magnetic field is due to processes in Earth's atmosphere
The geomagnetic field fluctuates with pulsations. Plasma waves (from the solar system and beyond) interacting with the Earth's magnetosphere.
Solar Wind. The Sun constantly emits a steady stream of highly charged positive and negative particles, called the "solar wind".
The Magnetosphere. Earth's geomagnetic field protects Earth from the onslaught of solar energy fields and solar winds, causing a distortion to its field --- a complex EMF called the magnetosphere. The magnetosphere represents the combination of the sun's energy and the geomagnetic field, with its edge being delineated by the ionosphere.
