Abstract
Ultraviolet images of Jupiter's northern aurora obtained in 2005 confirm the existence of an electromagnetic interaction between Europa and the Jovian ionosphere. The auroral signature shows a two‐component structure: a quasi‐circular Europa spot, followed by a previously undetected faint tail emission trailing in the direction of corotation flow. The characteristic brightness for the auroral spot is ∼14 ± 1 kR above background, and approximately 7 ± 1 kR for the tail. The spot's size is ∼1100 km, magnetically mapping to an interaction region ≤15 Europa diameters. The auroral tail extends over ∼5000 km, which maps along a region of at least 70 Europa diameters. The ultraviolet power emitted by both components varies from a fraction to several GW. The present study suggests auroral interaction at Europa similar to that at Io, but scaled‐down by an order of magnitude, including a sub‐corotating plasma plume in the geometrical wake of Europa.
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