also be facilitated by more "exotic" processes such as electrostatic effects. Methone has two sharply defined albedo regions, with albedos of 0.61±0.06 and 0.7±0.03. The darker of these regions is centered on Methone's leading side, reminiscent of the thermal anomalies on the leading hemispheres of Mimas and Tethys, and it has been suggested that increased exposure to electrons from Saturn's magnetosphere is responsible. However, in those examples, the thermal anomalies coincide with a distinct UV/IR coloration, which in the case of Methone is either highly subdued or undetectable. Thus a physical, rather than compositional difference may be responsible. Possibilities include variations in regolith grain size, compaction, or particle microstructure. Assuming that Methone is in hydrostatic equilibrium, i.e. that its elongated shape simply reflects the balance between the tidal force exerted by Saturn and Methone's gravity, its density can be estimated: , among the lowest density values obtained or inferred for a Solar System body. Relationship with Saturn's rings Material blasted off Methone by micrometeoroid impacts is believed to be the source of the Methone Ring Arc, a faint partial ring around Saturn co-orbital with Methone that was discovered in September 2006. References Bibliography External links Methone Profile by NASA's Solar System Exploration IAU Working Group for Planetary System Nomenclature Moons of Saturn 20040601 Moons with a prograde orbit