Large Quasi-Circular Features Beneath Frost on Triton

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Science  14 Feb 1992:
Vol. 255, Issue 5046, pp. 824-826
DOI: 10.1126/science.255.5046.824


Specially processed Voyager 2 images of Neptune's largest moon, Triton, reveal three large quasi-circular features ranging in diameter from 280 to 935 kilometers within Triton's equatorial region. The largest of these features contains a central, irregularly shaped area of comparatively low albedo about 380 kilometers in diameter, surrounded by crudely concentric annuli of higher albedo materials. None of the features exhibit significant topographic expression, and all appear to be primarily albedo markings. The features are located within a broad equatorial band of anomalously transparent frost that renders them nearly invisible at the large phase angles (α > 90°) at which Voyager obtained its highest resolution coverage of Triton. The features can be discerned at smaller phase angles (α = 66°) at which the frost only partially masks underlying albedo contrasts. The origin of the features is uncertain but may have involved regional cryovolcanic activity.