The Earth's plasmasphere as viewed with the EUV instrument on board the IMAGE spacecraft. The Earth is at the center of the images. The Sun is to the upper left. The view is toward Earth's north pole. The 30.4-nm emission from the plasmaspheric helium ions appears in false color as a pale blue cloud surrounding the Earth. The emission is brightest near the Earth on the day side owing to the increase in helium ion concentration with decreasing altitude and to the contribution of other ionized species, primarily atomic oxygen ions. The dark "bite out" seen in the lower right portion of the emission is the Earth's shadow. A faint "tail" of plasmaspheric material entrained in the sunward flow of plasma from the magnetotail and being carried toward the dayside magnetopause can be seen in the righthand image. Also clearly visible is the Earth's northern aurora, with a bright discrete arc near midnight evident in the lefthand image. The auroral emissions are believed to be from atomic oxygen ions at a wavelength of 53.9 nm, which the EUV imager also detects, although it is not the target wavelength for which the instrument was optimized.

The two images were acquired at different times during the same orbit on May 24, 2000. In the first image, the spacecraft is in the evening sector and has not yet passed over the north pole; in the second image, it has crossed the pole and is at or near apogee (7.2 Earth radii) on the morning side.

Click here for a selection of EUV plasmasphere movies. Also, visit the EUV web site at EUV web site at the University of Arizona for more movies and information about the EUV imager. (Information about the EUV instrument and investigation is also available on this web site as well.)

Photo and movie credit: B. Sandel and T. Forrester, Univ. of Arizona.