Here we report the combined spacecraft observations of Saturn acquired over one Saturnian year (~29.5 Earth years), from the Voyager encounters (1980-81) to the new Cassini reconnaissance (2009-10). The combined observations reveal a strong temporal increase of tropic temperature (~10 Kelvins) around the tropopause of Saturn (i.e., 50 mbar), which is stronger than the seasonal variability (~a f...

n what follows, we describe the technique and history of energetic neutral atom (enA) imaging of space plasma and present recent results from international collaborations involving enA imaging experiments as well as results from the imAge mission at earth and the cassini mission at Jupiter and saturn. both imAge and cassini carry ApL-built enA cameras. The henA instrument onboard the imAge miss...

Saturn rings are most beautiful and dynamic places in the solar system, consisting of ice particles in a constant battle between the gravitational forces of Saturn and its many moons. Fan, spiral, propellers, moonlets and streamer-channels observed by CASSINI in the F-ring have been attributed to encounters by Prometheus on the F ring, with investigations of optical thickness revealing large po...

We have detected in Cassini spacecraft data the signature of the periodic tidal stresses within Titan, driven by the eccentricity (e = 0.028) of its 16-day orbit around Saturn. Precise measurements of the acceleration of Cassini during six close flybys between 2006 and 2011 have revealed that Titan responds to the variable tidal field exerted by Saturn with periodic changes of its quadrupole gr...

The long-wavelength topography of Titan has an amplitude larger than that expected from tidal and rotational distortions at its current distance from Saturn. This topography is associated with small gravity anomalies, indicating a high degree of compensation. Both observations can be explained if Titan has a floating, isostatically-compensated ice shell with a spatially-varying thickness. The s...

Lightning was detected on several planets in the solar system, where it could also produce sprites in the upper layers of these atmospheres. Large sprite discharges at mesospheric altitudes on Earth have been found to be physically similar to streamer discharges in air at sea level density. Based on this understanding, we investigate possible sprite discharges on the Gas Giant planets and on Ve...

[1] The oppositely directed magnetic field in the kronian magnetic tail is expected eventually to reconnect across the current sheet, allowing plasma to escape in an anti-solar direction down the tail. This reconnection process accelerates ions and electrons both toward and away from the planet, allowing the magnetotail to relax to a more dipolar configuration. Previous missions to Saturn shed ...

The recent discovery of dense rings around the Centaur Chariklo (and possibly Chiron) reveals that complete dense planetary rings are not only found around Saturn and Uranus, but also around small bodies orbiting in the vicinity of those giant planets. This report examines whether or not there could be a physical process that would make rings more likely to form or persist in this particular pa...

We consider the motion of coorbital satellites in the framework of the Restricted Three Body problem for We show a mechanism to generate horsehoe periodic orbits and we compute some families of horseshoe periodic orbits when vary ing the Jacobian constant We conclude that there exist stable horseshoe periodic orbits which t with the motion of Saturn coorbital satellites Janus and Epimetheus

We present evolutionary sequences for Jupiter and Saturn, based on new nongray model atmospheres, which take into account the evolution of the solar luminosity and partitioning of dense components to deeper layers. The results are used to set limits on the extent to which possible interior phase separation of hydrogen and helium may have progressed in the two planets. When combined with static ...