This is an image of the type-B aurora of Earth, also called the SAR ARC.
L. Frank from Dynamics Explorer
Aurora has been seen in the atmosphere of Neptune which is centered around the magnetic pole, as it should be for type-A aurora, even so Neptune mostly has type-B aurora similar to the SAR ARC of Earth (shown here).
The rings of Neptune extend to 2.5 Rn, exactly where the plasmasphere is supposed to be, and sweep away much of the material there. Therefore there is only a small plasmasphere containing trapped particles, so there is a lot less plasma to create the aurora.
No radio signals from Neptune have been detected which relate to aurora or auroral processes, and scientists are still working to understand the currents which cause aurora.
Thus, from what little we know about the magnetosphere, much of the aurora of Neptune is thought to be created from the diffuse precipitation of particles into the atmosphere, very much like the formation of the terrestrial SAR ARC. These aurora are beautiful but much less dynamic than the type-A aurora found at the poles of the Earth or Jupiter.
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