We present an extensive data set of ~150 localized features from Cassini images of Saturn's A ring, a third of which are demonstrated to be persistent by their appearance in multiple images, and half of which are resolved well enough to reveal a characteristic "propeller" shape. We interpret these features as the signatures of small moonlets embedded within the ring, with diameters between 40 and 500 m. The lack of significant brightening at high phase angle indicates that they are likely composed primarily of macroscopic particles, rather than dust. With the exception of two features found exterior to the Encke Gap, these objects are concentrated entirely within three narrow (~1000 km) bands in the mid-A ring that happen to be free from local disturbances from strong density waves. However, other nearby regions are similarly free of major disturbances but contain no propellers. It is unclear whether these bands are due to specific events in which a parent body or bodies broke up into the current moonlets, or whether a larger initial moonlet population has been sculpted into bands by other ring processes.

We present an extensive data set of ~150 localized features from Cassini images of Saturn's Ring A, a third of which are demonstrated to be persistent by their appearance in multiple images, and half of which are resolved well enough to reveal a characteristic "propeller" shape. We interpret these features as the signatures of small moonlets embedded within the ring, with diameters between 40 and 500 meters. The lack of significant brightening at high phase angle indicates that they are likely composed primarily of macroscopic particles, rather than dust. With the exception of two features found exterior to the Encke Gap, these objects are concentrated entirely within three narrow (~1000 km) bands in the mid-A Ring that happen to be free from local disturbances from strong density waves. However, other nearby regions are similarly free of major disturbances but contain no propellers. It is unclear whether these bands are due to specific events in which a parent body or bodies broke up into the current moonlets, or whether a larger initial moonlet population has been sculpted into bands by other ring processes.

natural satellites of the planet Saturn

Four spacecraft have been sent to investigate the Saturnian system: Pioneer 11, Voyager 1, Voyager 2, and Cassini. By analyzing data acquired with these spacecraft together with Earth-based and Hubble Space Telescope satellite astrometry and Saturnian ring and satellite occultations, we constructed a model for the orientation and precession of Saturn's pole and determined gravitational parameters of the system and the orbits of the Saturnian satellites. This article provides details of our analysis and its results. *

Properties of the small inner satellites of Saturn are updated using final Cassini image data. The equatorial ridges on Pan and Atlas are morphologically, structurally, and gravitationally distinct from their cores and represent distinct additions to, rather than modifications of, the precursor bodies. Exposures of lineated substrates on Pandora and Epimetheus show a relationship between regolith grooves and structures in underlying bedrock. Structures exposed on Epimetheus suggest formation at depth including filling or annealing of fractures. These structures, and sharp bedrock-regolith boundaries indicate a history far more complex than simple rubble-pile assembly. These exposures of bedrock also indicate past removal of the expected regolith from large fractions of these object's surfaces late in their cratering records.

Context. Saturn has an excess of irregular moons. This is thought to be the result of past collisional events. Debris produced during such episodes in the neighborhood of a host planet can evolve into co-orbitals trapped in quasi-satellite and/or horseshoe resonant states. A recently announced centaur, 2013 VZ70, follows an orbit that could be compatible with those of prograde Saturn's co-orbitals. Aims. We perform an exploration of the short-term dynamical evolution of 2013 VZ70 to confirm or reject a co-orbital relationship with Saturn. A possible connection with Saturn's irregular moon population is also investigated. Methods. We studied the evolution of 2013 VZ70 backward and forward in time using N-body simulations, factoring uncertainties into the calculations. We computed the distribution of mutual nodal distances between this centaur and a sample of moons. Results. We confirm that 2013 VZ70 is currently trapped in a horseshoe resonant state with respect to Saturn but that it is a transient co-orbital. We also find that 2013 VZ70 may become a quasi-satellite of Saturn in the future and that it may experience brief periods of capture as a temporary irregular moon. This centaur might also pass relatively close to known irregular moons of Saturn. Conclusions. Although an origin in trans-Neptunian space is possible, the hostile resonant environment characteristic of Saturn's neighborhood favors a scenario of in situ formation via impact, fragmentation, or tidal disruption as 2013 VZ70 can experience encounters with Saturn at very low relative velocity. An analysis of its orbit within the context of those of the moons of Saturn suggests that 2013 VZ70 could be related to the Inuit group. Also, the mutual nodal distances of 2013 VZ70 and the moons Fornjot and Thrymr are below the first percentile of the distribution.

Tens of new moons around both Jupiter and Saturn have been announced on Minor Planet Electronic Circulars (MPECs) in late 2022 and early 2023. Jupiter now has 95 and Saturn 146 confirmed moons. Many smaller and fainter moons have also been detected at these planets but not yet confirmed through MPECs. These discoveries nearly complete the small moon population of Jupiter to about 2 km and Saturn to about 3 km and show new dynamical satellite families. The once lone Carpo is now joined by S/2018 J4, making it a group of two small prograde moons around Jupiter. The Inuit prograde family around Saturn appears to be 3 distinct groupings. S/2004 S24 seems to be a unique distant small Saturn prograde moon, as could be S/2006 S12 and S/2019 S6. S/2006 S20 might be the first found member of a compact Phoebe Saturn moon family.

Saturn's narrow F ring exhibits several unusual features that vary on timescales of hours to years. These include transient clumps, a central core surrounded by a multistranded structure and a regular series of longitudinal channels associated with Prometheus, one of the ring's two `shepherding' satellites. Several smaller moonlets and clumps have been detected in the ring's immediate vicinity, and a population of embedded objects has been inferred. Here we report direct evidence of moonlets embedded in the ring's bright core, and show that most of the F ring's morphology results from the continual gravitational and collisional effects of small satellites, often combined with the perturbing effect of Prometheus. The F-ring region is perhaps the only location in the Solar System where large-scale collisional processes are occurring on an almost daily basis.