New results from Saturn's moons

1 June 2011

Electrical currents linking Enceladus with its associated spot in Saturn's aurora

New results, published in Science and Nature, show that Saturn's moons can affect the planet's aurora and have their own atmospheres.

Enceladus-related aurora spotted

Enceladus is the major source of water and plasma filling Saturn’s inner magnetosphere. Saturn’s magnetosphere rotates rapidly past Enceladus – and its ionosphere is an electrical conductor. Like a dynamo, this drives electrical current along Saturn’s magnetic field towards the planet. In a recent paper in Nature, planetary group researchers contributed results and analysis from MSSL-UCL’s electron spectrometer on Cassini, measuring the electron current towards Saturn which then forms a spot in the Saturn’s Northern lights, or ‘aurora’. Similar spots associates with the moons Io, Ganymede and Europa are seen in Jupiter’s aurora (Pryor et al, Nature, April 2011)

Rhea’s oxygen and carbon dioxide atmosphere

Negative and positive ions picked up from atmosphere pinpoint near-surface source

Saturn’s second-largest moon, Rhea, has a tenuous atmosphere of its own, as recently reported in the journal Science. To pinpoint the source near the surface, planetary group researchers helped trace ions seen at the spacecraft but originating in the atmosphere, to their source near Rhea’s surface. The positive and negative ‘pickup’ ions follow a curved path in Saturn’s magnetic field – and the path depends on the polarity. (Teolis et al., Science, December 2010).

MSSL Contact: Prof. Andrew Coates, ajc [a t] mssl.ucl.ac.uk

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