Auroral Processes Associated with Saturn's Moon Enceladus

Observations from the Cassini spacecraft have shown that Saturn's small moon Enceladus emits a geyser-like plume of water vapor and small icy particles from volcano-like vents in its southern polar region. It has also been shown that the interaction of this plume with the rapidly rotating magnetosphere of Saturn produces UV auroral emissions in Saturn's atmosphere near the foot of the moon's magnetic flux tube. Just how the charged particles responsible for the aurora are accelerated is a topic of considerable current interest. In this chapter, we give an overview of auroral processes associated with Enceladus. We show that the interaction of the plume with Saturn's corotating magnetospheric plasma leads to a wide variety of effects, including strong local distortions of the planetary magnetic field, the acceleration of electron beams, the generation of whistler mode radio emissions, and the excitation of a standing Alfven wave that links Enceladus to Saturn's upper atmosphere. Many of these effects are similar to those observed near Jupiter's moon Io, which is known to produce auroral emissions near the foot of its magnetic flux tube, and to those occurring in the Earth's aurora.