文档介绍：CLBE001-ESS2E November 9, 2006 16:16
666 Encyclopedia of the Solar System
temperatures. Early IUE observations confirmed that C2H2 and Werner system bands. Synoptic observations of these
absorption bands are the dominant features in the 1650– ultraviolet emissions using IUE have shown that they vary
1850 A˚ wavelength region. Figure 3a shows the geometric with Jupiter’ic (not ary) longitude, and hence
albedo of Jupiter in the FUV wavelength range, displaying these emissions are ospheric phenomena. IUE ob-
C2H2 and NH3 features, derived using posite spec- servations have been used to construct a spatial map of
trum of Jupiter from the 1978–1980 time frame. the Lyman-alpha emission and the data indicate that the
The spectral geometric albedo of Jupiter as measured by emitting material is upwelling at about 50 m/s relative to
IUE at NUV wavelengths is shown in Fig. 3b. Most of this the surrounding material. More intensive ultraviolet ob-
spectral behavior is attributable to hazes that are high above servations with FUSE and HST instruments GHRS, FOC,
the cloud deck. The best-fit model (solid line in the figure) STIS, and ACS have measured the temporal variability
to the data occurs for a jovian cloud deck with a geometric within the aurora and temperature variations within the
albedo of and for a posed of particles with auroral ovals seen at both poles. These variations are reflec-
a single scattering albedo of . Though such a result tions of possible distortions in the ic field of Jupiter.
may not be able to provide an unambiguous identification HST measured the first detection of reversed Lyman-alpha
of the materials pose the haze, it can constrain emissions, which are linked to variable atomic hydrogen.
the eligible candidate materials that are suggested by other Estimates of vertical column densities (1–5 × 1016 cm−2)
observations. of atomic hydrogen above the auroral source have been
IUE observations also permitted an ammoni