Planetary Sciences Editors' Highlights

Saturn’s Dynamo Illuminates its Interior

Saturn’s oddly symmetrical magnetic field can be explained by models in which the active dynamo region is overlain by a thick, stable layer cooled more strongly at the poles.

Source: AGU Advances


The final stages of the Cassini spacecraft mission allowed the magnetic field of Saturn to be carefully mapped. The field is amazingly symmetrical, much more so than any other planetary body. Although the reasons for this symmetry are unknown, it must be a result of Saturn’s internal structure.

Yan and Stanley [2021] suggest that the field’s characteristics are a consequence of two factors. The first is the presence of a thick, stably stratified layer above the convecting dynamo region; this damps out the short-wavelength field characteristics. The second is stronger cooling of the stable layer at the poles, inducing thermal winds and producing a better match to the magnetic power spectrum.

A stably stratified layer was expected based on theoretical arguments about helium rain-out, so this paper strengthens those arguments. A remaining puzzle is what mechanism could be causing the thermal winds posited in this model.

Citation: Yan, C. & Stanley, S. [2021]. Recipe for a Saturn-like dynamo. AGU Advances, 2, e2020AV000318.

—Francis Nimmo, Editor, AGU Advances

Text © 2021. The authors. CC BY-NC-ND 3.0
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