For 10 points, name this region of the atmosphere that is above the thermosphere and contiguous with outer space.
The presence of interhemispheric particle fluxes prevents the extension of the Pannekoek-Rosseland field to this region. The reflection of far-ultraviolet light off clouds of hydrogen within this region produces the (*) geocorona. Its lower limit is known as the critical level where hydrogen molecules have sufficient velocity to escape earth's gravitational field and it contains the Van Allen belts. For 10 points, name this region of the atmosphere that is above the thermosphere and contiguous with outer space.
The presence of interhemispheric particle fluxes prevents the extension of the Pannekoek-Rosseland field to this region.
{exosphere}