资源环境科技发展态势分析平台

The Cassini spacecraft revealed that Saturn’s magnetic field displayed oscillations at a period originally thought to match the planetary rotation rate but later found not to. One of many proposed theories predicts that a polar twin-cell neutral weather system drives this variation, producing observable differences in flows within Saturn’s ionosphere. Here, using spectral observations of auroral emission lines taken by the Keck Observatory’s Near Infrared Echelle Spectrograph (Keck-NIRSPEC) in 2017, we derive ion line-of-sight velocity maps after grouping spectra into rotational quadrants matching the phase of the planetary magnetic field. We measure 0.5 km s⁻¹ wind systems in the ionosphere consistent with the predicted neutral twin-vortex flow pattern. These findings demonstrate that neutral winds in Saturn’s polar regions cause the rotational period, as determined via the magnetic field, to exhibit a difference and time variability relative to the planet’s true period of rotation.