Peculiar rainbows in Saturn’s E ring: Uncovering luminous bands near Enceladus

We report observations of stripe-like features in Enceladus’ plumes captured simultaneously by Cassini’s VIMS-IR and ISS NAC instruments during flyby E17, with similar patterns seen in VIMS-IR data from flyby E13 and E19. These parallel stripes, inclined at approximately 16°to the ecliptic and 43°to Saturn’s ring plane, appear continuous across images when projected in the J2000 frame. A bright stripe, most visible at wavelengths around 5 μ m , acts as the zeroth-order diffraction peak of a reflection grating with an estimated groove spacing of 0.12–2.60 mm, while adjacent stripes are attributed to higher-order diffraction peaks. We suggest that this light-dispersing phenomenon originates from an inclined periodic structure within Saturn’s E ring. This structure, constrained between Saturn’s G-ring and Rhea’s orbit, likely consists of fresh ice particles supplied by Enceladus’ plumes. • Cassini’s ISS and VIMS uncover luminous, rainbow-like stripes near Enceladus. • Stripes show chromatic shifts, indicating diffraction by a millimetre-sized structure. • A bright band at 5 μ m lies at the centre of the stripe pattern. • Spectra hint at fresh, crystalline ice with large grains and solid CO 2 traces. • Discovery suggests an inclined, periodic ice formation in Saturn’s E ring.