Rotating auroral current system and reconnection sites on Saturn

Energetic charged particles trapped in a planet’s magnetosphere can produce stunning aurorae when they travel along the magnetic field lines and eventually collide with the planet’s atmosphere. Magnetic reconnection is one of the key processes in driving plasma and energy transport in the magnetosphere, and also a fundamental plasma process in energizing charged particles. Here, using in-situ measurements from the Cassini spacecraft, we report multiple small-scale reconnection sites that rotated with the magnetosphere. The spatial distribution of the identified long-standing multiple small reconnection site sequences shows no significant preference on local times. A chain of field- aligned currents is also found in Saturn’s magnetosphere that generates separated auroral patches. Both the multiple currents and their energy sources in the magnetodisc are azimuthally separated and rotate with the planet. The generation of the rotating azimuthally distributed field-aligned currents might be associated with the rotating long-standing small-scale reconnection processes.