Reacción a "A Spanish team has discovered a decagonal wave at Saturn’s south pole for the first time"

Images of Saturn’s northern polar region reveal a unique hexagonal structure, which has been present at least since Voyager took the first close-up images in 1980. The atmospheres of Jupiter and Saturn – gas giants that rotate rapidly with periods of approximately 10 hours – are characterised by the presence of fast zonal winds (blowing parallel to the equator). The hexagon is visible because a fast jet stream near the pole is deflected meridionally, forming a stable wave that carries with it the clouds which trace the movement of the winds. Cassini enabled this wave to be studied in detail; it extends from the troposphere to higher regions of the atmosphere.

This paper shows how, since 2023, a similar structure has appeared in the subpolar region of the southern hemisphere, this time in the form of a decagon. The paper provides an exhaustive description of the properties of this new structure at different altitudes in the atmosphere (which can be characterised in images taken with different filters). Unlike the hexagon, the decagon does not remain stable relative to the planet; rather, its vertices shift eastwards, not in a completely regular manner, but exhibiting a 32-day oscillation.

The study provides new insights into why gas giants tend to sustain periodic structures in their polar regions (which, on Jupiter, manifest as a regular set of vortices). In the case of the hexagon, it was initially postulated that it might have been generated by the interaction of the jet stream with a vortex, although the wave-like disturbance has outlived the vortex that may have generated it. Now, in the south, a vortex is observed near the decagon, and this study uses simulations to analyse the possibility that it is the origin of the new decagonal structure. Future observations will enable us to determine whether the decagon that has now formed is as stable as the hexagon in the north. In any case, for the time being, this study paves the way for further analyses that will allow us to better understand the fascinating dynamics of these atmospheres.