Formation of lapetus' Extreme Albedo Dichotomy by Exogenically Triggered Thermal Ice Migration

The extreme albedo asymmetry of Saturn's moon lapetus, which is about 10 times as bright on its trailing hemisphere as on its leading hemisphere, has been an enigma for three centuries. Deposition of exogenic dark material on the leading side has been proposed as a cause, but this alone cannot...

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Bibliographic Details
Published inScience (American Association for the Advancement of Science) Vol. 327; no. 5964; pp. 432 - 435
Main Authors Spencer, John R., Denk, Tilmann
Format Journal Article
LanguageEnglish
Published Washington, DC American Association for the Advancement of Science 22.01.2010
Subjects
Albedo
Artificial satellites
Astronomy
Earth, ocean, space
Exact sciences and technology
Hemispheres
Ice
Inertia
Italian ices
Materials
Planetary, asteroid, and satellite characteristics and properties
Planets, their satellites and rings. Asteroids
Saturn
Saturnian satellites
Solar system
Sublimation
Surface features, cratering, and topography
Tropical regions
Saturn planet
Albedo
Iapetus
Asymmetry
Sublimation
Saturn satellite
Ice
High temperature
Slow rotation
Complexity
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Summary:The extreme albedo asymmetry of Saturn's moon lapetus, which is about 10 times as bright on its trailing hemisphere as on its leading hemisphere, has been an enigma for three centuries. Deposition of exogenic dark material on the leading side has been proposed as a cause, but this alone cannot explain the global shape, sharpness, and complexity of the transition between lapetus' bright and dark terrain. We demonstrate that all these characteristics, and the asymmetry's large amplitude, can be plausibly explained by runaway global thermal migration of water ice, triggered by the deposition of dark material on the leading hemisphere. This mechanism is unique to lapetus among the satumian satellites because its slow rotation produces unusually high daytime temperatures and water ice sublimation rates for a given albedo.
ISSN:0036-8075
1095-9203
DOI:10.1126/science.1177132