Saturn's moon Enceladus is the source of Saturn's E-ring, confirms research published today. Writing in the journal Science, scientists show how a plume of icy water vapour bursting out of the South Pole of Enceladus replenishes the water particles that make up the E-ring and creates a dynamic water-based atmosphere around the small moon. The E-ring is Saturn's outermost ring and is composed of microscopic particles. It is very diffuse and stretches between the orbit of two of Saturn's moons, Mimas and Titan.