Chasing Rainbows on Enceladus: Discovery of an Inclined Periodic Structure in the Saturnian System

Abstract

Saturn's icy moon, Enceladus, has captivated scientists since NASA's Cassini spacecraft discovered massive plumes of water vapour and ice erupting from its south pole. The goal of this study was to present a novel opportunity to characterise the particles in the plumes by searching for optical phenomena such as rainbows and halos in the geysers of Enceladus using Cassini's remote sensing data. During several flybys, we discovered unusual stripe-like patterns within these plumes using simultaneous observations in the Cassini VIMS (Visible and Infrared Mapping Spectrometer) and ISS (Imaging Science Subsystem). This anomaly, unlike any other known optical phenomenon, indicates the presence of an inclined, periodic, millimetre-sized structure in the Saturnian system. We propose two hypotheses for these patterns: they may be caused by a periodic structure in Saturn's Norse group orbits or the E-ring. This unexpected discovery could offer new insights into the particle dynamics within Saturn's environment.