SPECTRA OF JUPITER AND SATURN IN PHOTOGRAPHIC INFRARED

Recent studies of the near-infrared spectra of Jupiter and Saturn have led to new evaluations of the relative abundances of atmospheric constituents and some indication of the distribution of these constituents with altitude. It appears that the atmospheres of both of these planets may exhibit a roughly solar composition, but additional precision in the derivation of abundances is required to settle this question. A preliminary model for the atmospheric structure of Jupiter that accommodates observations made at a variety of wavelengths is discussed. The model suggests that UV observations only reach a level near the tropopause, while in the near-infrared the lower bound of the observable atmosphere is set by a dense cloud layer whose upper boundary has a temperature of 225°K. Between this level and the tropopause there is a region of ammonia crystal clouds. Direct observation of this haze layer is made possible by photography of the planet through a filter centered on a strong methane band. The distribution of the haze is nonuniform and time-variable, showing hoods over the poles and a local anomaly over the Great Red Spot. © 1969.