Ionizing nightglow - Sources, intensity, and spatial distribution

Photometers carried aboard an Aerobee rocket mapped the ultraviolet night sky at White Sands, New Mexico. Maps for five 300 A passbands in the wavelength range 170 to 1400 A reveal spatial radiation patterns unique to each spectral subregion. The major ultraviolet features seen in these maps are ascribed to a variety of sources: (1) solar Lyman alpha and Lyman beta, resonantly scattered by geocoronal hydrogen; (2) solar He II resonantly scattered by ionized helium in the earth's plasmasphere; (3) solar He I resonantly scattered by neutral helium in the interstellar wind and Doppler shifted so that it penetrates the earth's helium blanket; and (4) starlight in the 912 to 1400 A band, primarily from early-type stars in the Orion region. Not explained is the presence of small but measurable albedo signals observed near the peak of flight. Intensities vary from several kilorayleighs for Lyman alpha to a few Rayleighs for He II.