Epimetheus, Janus, Pandora and Prometheus Amid the Rings

Two pairs of moons make a rare joint appearance. The F ring's shepherd moons, Prometheus and Pandora, appear just inside and outside of the F ring (the thin faint ring furthest from Saturn). Meanwhile, farther from Saturn the co-orbital moons Janus (near the bottom) and Epimetheus (about a third of the way down from the top) also are captured.

Prometheus (53 miles, or 86 kilometers across) and Pandora (50 miles, or 81 kilometers across) sculpt the F ring through their gravitational influences. Janus (111 miles, or 179 kilometers across) and Epimetheus (70 miles, or 113 kilometers across) are famous for their orbital dance, swapping places about every four years. They are also responsible for gravitationally shaping the outer edge of the A ring into seven scallops.

This view looks toward the sunlit side of the rings from about 47 degrees above the ringplane. The image was taken in visible light with the Cassini spacecraft wide-angle camera on October 11, 2013.

The view was acquired at a distance of approximately 810,000 miles (1.3 million kilometers) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 47 degrees. Image scale is 47 miles (76 kilometers) per pixel.

Photo credit: NASA/JPL-Caltech/Space Science Institute

Crescent Saturn

Saturn, which appears as only a thin, lit crescent, broken only by the shadows of its rings, poses gracefully for the Cassini spacecraft cameras.

This view looks toward the unilluminated side of the rings from about 42 degrees below the ringplane. The image was taken with the Cassini spacecraft wide-angle camera on September 20, 2013 using a spectral filter which only admits wavelengths of near-infrared light centered at 752 nanometers.

The view was obtained at a distance of approximately 1.4 million miles (2.3 million kilometers) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 142 degrees. Image scale is 84.5 miles (136 kilometers) per pixel.

Photo credit: NASA/JPL-Caltech/Space Science Institute

Rhea

A nearly full Rhea shines in the sunlight in this recent Cassini image.

Rhea (949 miles, or 1,527 kilometers across) is Saturn's second largest moon.

Lit terrain seen here is on the Saturn-facing hemisphere of Rhea. North on Rhea is up and rotated 43 degrees to the left. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on September 10, 2013.

The view was obtained at a distance of approximately 990,000 miles (1.6 million kilometers) from Rhea. Image scale is 6 miles (9 kilometers) per pixel.

Photo credit: NASA/JPL-Caltech/Space Science Institute

Titan's Internal Structure

This artist’s concept shows a possible model of Titan’s internal structure that incorporates data from NASA’s Cassini spacecraft. In this model, Titan is fully differentiated, which means the denser core of the moon has separated from its outer parts. This model proposes a core consisting entirely of water-bearing rocks and a subsurface ocean of liquid water. The mantle, in this image, is made of icy layers, one that is a layer of high-pressure ice closer to the core and an outer ice shell on top of the sub-surface ocean.

A model of Cassini is shown making a targeted flyby over Titan’s cloudtops, with Saturn and Enceladus appearing at upper right.

The model, developed by Dominic Fortes of University College London, England, incorporates data from Cassini’s radio science experiment.

Image credit: A. D. Fortes/UCL/STFC

Note: For more information, see Cassini Nears 100th Titan Flyby with a Look Back.

Ring Spokes and Mimas

Among the interplay of Saturn's shadow and rings, Mimas, which appears in the lower-right corner of the image, orbits Saturn as a set of the ever-intriguing spokes appear in the B ring (just to the right of center).

Scientists expect that spokes will soon cease to form as Saturn approaches northern equinox. The exact mechanism of spoke formation is still the subject of debate, but ring scientists do know that spokes no longer appear when the Sun is higher in Saturn's sky. It is believed that this has to do with the ability of micron-sized ring grains to maintain an electrical charge and levitate above the rings, forming spokes. Thus, these may be some of the last spokes ever imaged by Cassini.

This view looks toward the unilluminated side of the rings from about 38 degrees below the ringplane. The image was taken in visible light with the Cassini spacecraft wide-angle camera on October 22, 2013.

The view was obtained at a distance of approximately 1.6 million miles (2.6 million kilometers) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 146 degrees. Image scale is 93 miles (150 kilometers) per pixel.

Photo credit: NASA/JPL-Caltech/Space Science Institute