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A far-ultraviolet camera/spectograph experiment was operated on the lunar surface during the Apollo 16 mission. Among the data obtained were images and spectra of the terrestrial atmosphere and geocorona in the wavelength range below 1600 angstroms. These gave the spatial distributions and relative intensities of emissions due to atomic hydrogen, atomic oxygen, molecular nitrogen, and other species-some observed spectrographically for the first time.

Lyman α imagery of the hydrogen geocorona was obtained from the lunar surface during the Apollo 16 mission. The images are of 20° diameter fields, with 2 arc min limiting resolution, centered on the earth and about 12° upsun of the earth. The data confirm that the hydrogen geocorona is detectable above the interplanetary Lyman α background to more than 15 RE in the upsun direction. In the antisolar direction there is a pronounced ‘geotail’ effect due to solar Lyman α radiation pressure, which is markedly asymmetric about the sun line. Comparison of the data with theoretical models shows quite good agreement, particularly in the vicinity of 3 RE. In agreement with other observations the hydrogen density is lower than the theoretical density in the far‐upsun direction, and very close to the earth there is a buildup of hydrogen on the dark side.

Emissions of atomic oxygen (1304 angstroms), atomic carbon (1657 angstroms), and atomic hydrogen (1216 angstroms) from Comet Kohoutek were observed with ultraviolet cameras carried on a sounding rocket on 8 January 1974. Analysis of the Lyman alpha halo at 1216 angstroms gave an atomic hydrogen production rate of 4.5 x 10(29) atoms per second.