Short answers, pulled from the story.
Saturn's magnetosphere was discovered on the 1st of September 1979, when the Pioneer 11 spacecraft passed through it and measured the planet's magnetic field directly. Earlier radio detections in 1974 had suggested a field might exist, but Pioneer 11 provided the first definitive evidence.
The moon Enceladus is the dominant plasma source in Saturn's magnetosphere, releasing 300-600 kilograms of water vapor per second through geysers near its south pole. At least 100 kilograms of that water is ionized every second and added to the co-rotating plasma.
Saturn's magnetosphere is the second largest in the Solar System, after Jupiter's. The boundary between Saturn's magnetosphere and the solar wind sits at an average distance of about 22 Saturn radii from the planet's center, with a magnetotail extending hundreds of Saturn radii on the night side.
Saturn kilometric radiation (SKR) is a powerful low-frequency radio emission spanning roughly 10-1,300 kilohertz with a total output of about 1 gigawatt. It is generated by electrons moving along magnetic field lines in the auroral regions of Saturn through a process called the Cyclotron Maser Instability.
Saturn's true rotation period is unknown because the radio emissions traditionally used to measure planetary rotation rates do not reliably track Saturn's interior. The modulation period of Saturn kilometric radiation varies by as much as 1 percent on a timescale of 20-30 days and correlates with solar wind speed rather than a fixed planetary rotation, making a precise determination impossible as of 2010.
Energetic particles in Saturn's magnetosphere strike the icy surfaces of moons like Rhea and Dione, breaking apart water molecules through radiolysis and producing ozone, hydrogen peroxide, and molecular oxygen. Ozone has been detected on the surfaces of both Rhea and Dione, and the oxygen released forms thin atmospheres around the rings and moons.