Jupiter's Ultraviolet Aurora from Galileo Ultraviolet Spectrometer Observations
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In 1996 and 1997 the Galileo Ultraviolet Spectrometer (UVS) obtained the first measurements of Jupiter's nightside midultraviolet (MUV) polar auroral spectrum from 1620 to 3231 A at 13 A resolution.
In 1996 during the first four orbits of the satellite tour the Galileo ultraviolet spectrometer (UVS) (1130-4320 A) and extreme ultraviolet spectrometer (EUVS)(540-1280 A) performed near-simultaneous observations of the Jupiter aurora in both the north and south polar regions.
In its December 1990 fly-by of Earth, the Galileo spacecraft found evidence of abundant gaseous oxygen, a widely distributed surface pigment with a sharp absorption edge in the red part of the visible spectrum, and atmospheric methane in extreme thermodynamic disequilibrium; together, these are strongly suggestive of life on Earth. Moreover, the presence of narrow-band, pulsed, amplitude-modulated radio transmission seems uniquely attributable to intelligence. These observations constitute a control experiment for the serach for extraterrestrial life by modern interplanetary spacecraft.
Multiple-scattering radiative transfer calculations were used to deduce the vertical cloud structure (VCS) of Jupiter's equatorial region. The VCS model of the equatorial plumes is obtained through an analysis of Voyager images of the 6190-A methane band and the 6000-A continuum, and ground-based 8900-A methane band images. The VCS of the equatorial plumes is found to be consistent with the hypothesis that the plumes are caused by upwelling at the ammonia condensation level produced by buoyancy due to latent heat release from the condensation of water clouds nearly three scale heights below the plumes.