Views of Earth's magnetosphere with the IMAGE satellite

The IMAGE spacecraft uses photon and neutral atom imaging and radio soundin g techniques to provide global images of Earth's inner magnetosphere and up per atmosphere. Auroral imaging at ultraviolet wavelengths shows that the p roton aurora is displaced equatorward with respect to the electron aurora a nd that discrete auroral forms at higher Latitudes are caused almost comple tely by electrons. Energetic neutral atom imaging of ions injected into the inner magnetosphere during magnetospheric disturbances shows a strong ener gy-dependent drift that Leads to the formation of the ring current by ions in the several tens of kiloelectron volts energy range. Ultraviolet imaging of the plasmasphere has revealed two unexpected features-a premidnight tro ugh region and a dayside shoulder region-and has confirmed the 30-year-old theory of the formation of a plasma tail extending from the duskside plasma sphere toward the magnetopause.