This is an image of the type-B aurora of Earth, also called the SAR ARC.
L. Frank from Dynamics Explorer
Even though aurora have been seen in the atmosphere of Uranus (which is centered around the magnetic pole as it should be for type-A aurora) Uranus mostly has type-B aurora similar to the SAR ARC of Earth (shown here).
The rings of Uranus extend to 1.95 Ru, 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, and a lot less plasma can be forced from the magnetosphere down into the atmosphere to create the aurora.
The type-A aurora probably comes from current systems which connect the moon Miranda to the magnetic pole of Uranus, however radio signals, which are thought to arise when the aurora is being created, are very weak at Uranus. This makes reconstruction of the processes which give rise to the aurora difficult.
Thus, from what little we know about the magnetosphere, much of the aurora of Uranus 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.
Shop Windows to the Universe Science Store!
Our online store
on science education, ranging from evolution
, classroom research
, and the need for science and math literacy
You might also be interested in:
The aurora we are most familiar with is the polar aurora. This is what people are referring to when they speak of the northern or southern lights. But there are other less-known auroral activity, such...more
Uranus' plasmasphere is tiny. The rings of Uranus sweep away much of the particles in the area. Particles enter the plasmasphere from the atmosphere as well as the magnetotail. Mathematical theory suggests...more
This picture illustrates the streaming of particles into and out of the auroral zone, as Field-aligned currents (FAC's) short-circuit through the ionosphere. Some of the particles entering the auroral...more
There is not very much radio noise within the magnetosphere of Uranus. Signals are observed with much less power than observed at Saturn, but several times greater than observed at Earth. The signals...more
The magnetosphere of Uranus is medium sized, but still much larger than the Earth's. It extends well beyond the orbits of Uranus' moons. It is probably generated in the icy interior layers, rather than...more
The planet Uranus has an odd magnetic field. The planet's magnetic poles are nowhere near the geographic poles (as defined by the spin axis) of Uranus. A portion of the magnetic field of Uranus is a dipole...more
Besides methane, Uranus' atmosphere contains more sophisticated atmospheric molecules such as ethane gas, acetylene, and diacetylene. All these molecules form layers of haze at different altitudes high...more