Saturn’s magnetic field
What has Cassini told us about the field surrounding Saturn?
Cassini’s measurements confirm that Saturn’s magnetic field is curiously well aligned to its axis of rotation.
Shaped by the Sun
Saturn’s magnetosphere is sculpted into a teardrop shape by interactions with the Sun’s own magnetic field and the solar wind.
Weak radiation belts lie just inside and outside the rings – the ring particles and moons tend to soak up the energetic particles that would otherwise create more intense belts.
The magnetic field is generated by masses of electrically charged fluid rotating inside the planet.
The outer reaches of the magnetic field are flattened into a disc-like structure with a ‘ring current’ flowing around it.
The magnetosphere is filled with a plasma containing electrically charged particles from a variety of sources – mostly water vapour from Enceladus.
Because the magnetosphere is aligned with Saturn’s polar axis it can’t be used to measure the planet’s rotation. As a result, even after Cassini we still don’t know how fast Saturn’s interior spins!
Saturn’s giant moon has no intrinsic magnetism of its own, but its atmosphere is protected by an induced magnetic field as it moves through Saturn’s magnetosphere.