ARC-1989-AC89-7003

Range : 16 million km (9.9 million miles) P-34616 This series of six Voyager 2 images of Neptune through different filters reveals altitude in Neptune's clouds. The top three images, taken though orange, violet, and ultraviolet filters by the narrow-angle camera, show several bright cloud features, clearly visible in each image. The 'scooter' cloud, at 42 degrees south latitude, although prominent in the orange image, is invisible in ultraviolet, where scattering by atmospheric molecules is strongest. The disappearance can be understood if the 'scooter cloud has more obscurring atmosphere above it ( i.e. the scooter cloud is lower ) than other bright clouds. The observation also suggest that the centrally located Great Dark Spot is also a low lying feature because it also loses visiblity in the ultraviolet image. The lower three wide angle images ( from left to right: orange, weak methane [541nm], and strong methane [619nm] are arranged in increasing absorption by methane in Neptune's atmosphere. In the lower images the 'scooter cloud' becomes less obvious from left to right, implying there is relatively more absorbing methane above the 'scooter cloud'. Thus the set of images also implies that the 'scooter cloud' is deeper in the atmosphere ( and therefore at higher atmospheric pressure ) than the other bright clouds.