Ultraviolet observations of Uranus and Neptune

Far and extreme ultraviolet observations of Uranus and Neptune, principally by the ultraviolet spectrometer (UVS) on Voyager 2, are reviewed. Occultat ion observations have characterized the temperature, energy deposition, and major-constituent compositional profiles of these atmospheres above the 0. 1-1 mbar level. Observations of airglow, light emitted by these atmospheres , are more complex to interpret but yield insight into atmospheric energy b alance and chemistry. (C) 1999 Elsevier Science Ltd. All rights reserved.