The discovery of the plasmasphere grew out of the scientific study of
whistlers, natural phenomena caused by very low frequency (VLF) radio waves. Whistlers were first heard by radio operators in the 1890s. British scientist
Llewelyn Robert Owen Storey had shown
lightning generated whistlers in his 1953 PhD
dissertation. Around the same time, Storey had posited the existence of whistlers meant plasma was present in
Earth's atmosphere, and that it moved radio waves in the same direction as
Earth's magnetic field lines. Throughout the 1970s, Storey continued studying VLF waves using data gathered by FR-1. In 2014
satellite observations from the
THEMIS mission have shown that density irregularities such as plumes or biteouts may form. It has also been shown that the plasmasphere does not always co-rotate with the Earth. The plasma of the magnetosphere has many different levels of temperature and concentration. The coldest magnetospheric plasma is most often found in the plasmasphere. However, plasma from the plasmasphere can be detected throughout the magnetosphere because it gets blown around by the Earth's electric and magnetic fields. Data gathered by the twin
Van Allen Probes show that the plasmasphere also limits highly-energetic
ultrarelativistic electrons from
cosmic and
solar origin from reaching low earth orbits and the surface of the planet. File:Earth_plasmasphere.jpg|A view from the
IMAGE satellite showing Earth's plasmasphere using its Extreme Ultraviolet (EUV) imager instrument. File:Radiation Belts & Plasmapause.ogv|Visualization of the radiation belts with confined charged particles (blue & yellow) and plasmapause boundary (blue-green surface). ==See also==