s our robotic emissary to Saturn, the Cassini spacecraft is privileged to behold such fantastic sights as this pairing of two moons beyond the rings. The bright, narrow F ring is the outermost ring structure seen here

NASA Cassini spacecraft looks toward Saturn tiny moon Aegaeon within the G-ring arc. The moonlet Aegaeon formerly known as S/2008 S 1 cant be seen in this image, but it orbits in the bright arc of Saturn faint G ring shown here.

This image obtained by NASA Cassini spacecraft of the outer edge of Saturn?s B ring, reveals the combined effects of a tugging moon and oscillations that can naturally occur in disks like Saturn rings and spiral galaxies.

A technician is pictured at the Marshall Space Flight Center welding the Y-ring to the S-IC stage bulkhead and the fuel tank for the Saturn V SA-502 launch vehicle (Apollo 6 mission) in building 4705. The size of the S-IC required a special rig known as the Y-ring to join the tank wall cylinders and domes together. The Y-ring was designed to eliminate lap joints where the tank domes, wall, and adjoining structure (such as the intertank segment) came together.

This image shows a region in Saturn's outer B ring. NASA's Cassini spacecraft viewed this area at a level of detail twice as high as it had ever been observed before. The view here is of the outer edge of the B ring, at left, which is perturbed by the most powerful gravitational resonance in the rings: the "2:1 resonance" with the icy moon Mimas. This means that, for every single orbit of Mimas, the ring particles at this specific distance from Saturn orbit the planet twice. This results in a regular tugging force that perturbs the particles in this location. A lot of structure is visible in the zone near the edge on the left. This is likely due to some combination of the gravity of embedded objects too small to see, or temporary clumping triggered by the action of the resonance itself. Scientists informally refer to this type of structure as "straw." This image was taken using a fairly long exposure, causing the embedded clumps to smear into streaks as they moved in their orbits. Later Cassini orbits will bring shorter exposures of the same region, which will give researchers a better idea of what these clumps look like. But in this case, the smearing does help provide a clearer idea of how the clumps are moving. This image is a lightly processed version, with minimal enhancement; this version preserves all original details present in the image. Another other version (Figure 1) has been processed to remove the small bright blemishes due to cosmic rays and charged particle radiation near the planet -- a more aesthetically pleasing image, but with a slight softening of the finest details. The image was taken in visible light with the Cassini spacecraft wide-angle camera on Dec. 18, 2016. The view was obtained at a distance of approximately 32,000 miles (52,000 kilometers) from the rings and looks toward the unilluminated side of the rings. Image scale is about a quarter-mile (360 meters) per pixel. http://photojournal.jpl.nasa.gov/catalog/PIA21057

This image from NASA's Cassini mission shows a region in Saturn's A ring. The level of detail is twice as high as this part of the rings has ever been seen before. The view contains many small, bright blemishes due to cosmic rays and charged particle radiation near the planet. The view shows a section of the A ring known to researchers for hosting belts of propellers -- bright, narrow, propeller-shaped disturbances in the ring produced by the gravity of unseen embedded moonlets. Several small propellers are visible in this view. These are on the order of 10 times smaller than the large, bright propellers whose orbits scientists have routinely tracked (and which are given nicknames for famous aviators). This image is a lightly processed version, with minimal enhancement, preserving all original details present in the image. he image was taken in visible light with the Cassini spacecraft wide-angle camera on Dec. 18, 2016. The view was obtained at a distance of approximately 33,000 miles (54,000 kilometers) from the rings and looks toward the unilluminated side of the rings. Image scale is about a quarter-mile (330 meters) per pixel. http://photojournal.jpl.nasa.gov/catalog/PIA21059

NASA's Cassini spacecraft zoomed in on Saturn's A ring, revealing narrow, detailed structures that get even finer as the cameras' resolution increases. Even at this level of detail, it is still not fine enough to resolve the individual particles that make up the ring. High-resolution images like this help scientists map the fine structure of Saturn's rings. Features less than a half a mile (one kilometer) in size are resolvable here. But the particles in the A ring typically range in size from several meters across down to centimeters, making them still far too small to see individually here. This view looks toward the sunlit side of the rings from about 38 degrees above the ring plane. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Jan. 9, 2017. The view was obtained at a distance of approximately 70,000 miles (113,000 kilometers) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 11 degrees. Image scale is 2,300 feet (690 meters) per pixel. http://photojournal.jpl.nasa.gov/catalog/PIA20526

NASA's Cassini spacecraft captured these remarkable views of a propeller feature in Saturn's A ring on Feb. 21, 2017. These are the sharpest images taken of a propeller so far, and show an unprecedented level of detail. The propeller is nicknamed "Santos-Dumont," after the pioneering Brazilian-French aviator. This observation was Cassini's first targeted flyby of a propeller. The views show the object from vantage points on opposite sides of the rings. The top image looks toward the rings' sunlit side, while the bottom image shows the unilluminated side, where sunlight filters through the backlit ring. The two images presented as figure 1 are reprojected at the same scale (0.13 mile or 207 meters per pixel) in order to facilitate comparison. The original images, which have slightly different scales, are also provided here, without reprojection, as figure 2; the sunlit-side image is at left, while the unlit-side image is at right. Cassini scientists have been tracking the orbit of this object for the past decade, tracing the effect that the ring has upon it. Now, as Cassini has moved in close to the ring as part of its ring-grazing orbits, it was able to obtain this extreme close-up view of the propeller, enabling researchers to examine its effects on the ring. These views, and others like them, will inform models and studies in new ways going forward. Like a frosted window, Saturn's rings look different depending on whether they are seen fully sunlit or backlit. On the lit side, the rings look darker where there is less material to reflect sunlight. On the unlit side, some regions look darker because there is less material, but other regions look dark because there is so much material that the ring becomes opaque. Observing the same propeller on both the lit and unlit sides allows scientists to gather richer information about how the moonlet affects the ring. For example, in the unlit-side view, the broad, dark band through the middle of the propeller seems to be a combination of both empty and opaque regions. The propeller's central moonlet would only be a couple of pixels across in these images, and may not actually be resolved here. The lit-side image shows that a bright, narrow band of material connects the moonlet directly to the larger ring, in agreement with dynamical models. That same thin band of material may also be obscuring the moonlet from view. Lengthwise along the propeller is a gap in the ring that the moonlet has pried open. The gap appears dark on both the lit and unlit sides. Flanking the gap near the moonlet are regions of enhanced density, which appear bright on the lit side and more mottled on the unlit side. One benefit of the high resolution of these images is that, for the first time, wavy edges are clearly visible in the gap. These waves are also expected from dynamical models, and they emphasize that the gap must be sharp-edged. Furthermore, the distance between the wave crests tells scientists the width of the gap (1.2 miles or 2 kilometers), which in turn reveals the mass of the central moonlet. From these measurements, Cassini imaging scientists deduce that the moonlet's mass is comparable to that of a snowball about 0.6 mile (1 kilometer) wide. For the original images, the lit-side image has a scale of 0.33 mile (530 meters) per pixel in the radial (or outward from Saturn) direction and 0.44 mile (710 meters) per pixel in the azimuthal (or around Saturn) direction. The different scales are the result of Cassini's vantage point being off to the side of the propeller, rather than directly above it. The unlit-side image has a scale of 0.25 (410 meters) per pixel in both directions. In order to preserve its original level of detail, the image has not been cleaned of bright blemishes due to cosmic rays and to charged particle radiation from Saturn. http://photojournal.jpl.nasa.gov/catalog/PIA21433

Orbit Quest

As the particles comprising Saturn A ring slip into the planet shadow, they find themselves briefly in the penumbra of Saturn shadow

Moons in Transit

A pair of Saturn small satellites, Janus and Pandora, accompany the planet rings in this image from NASA Cassini spacecraft presenting the view in dramatic diagonal fashion.

A vertically extended structure or object in Saturn F ring casts a shadow long enough to reach the A ring in this Cassini image taken just days before planet August 2009 equinox.

From on high, the Cassini spacecraft spies a group of three ring moons in their travels around Saturn. Janus is seen at top, while Pandora hugs the outer edge of the narrow F ring. More difficult to spot is Pan, which is a mere speck in this view.

Immense Saturn is visible through the A ring as Pan coasts along its private corridor

Saturn rings cast shadows on the planet, except their shadows appear to be inside out in this image captured by NASA Cassini spacecraft.

Three Meddlesome Moons

Cassini scientists continue their quest to understand the origin and evolution of the newly discovered features observed in Saturn A ring which have become known as propellers as shown in this image from NASA Cassini spacecraft.

The shadow of Saturn rings looks like a belt fastened around the planet equator in this image. Overexposure to bring out the ring details makes Saturn appear especially bright.

Subtle Kinks

The Encke Gap moon, Pan, has left its mark on a scalloped ringlet of the Encke Gap. The moon creates these perturbations as it sweeps through the 325-kilometer 200-mile gap in the A ring

Possible variations in chemical composition from one part of Saturn ring system to another are visible in this archival image from NASA Voyager 2.

Wide-Angle Image of Saturn Rings

Two of Saturn small moons can be seen orbiting beyond the planet thin F ring in this image captured by NASA Cassini spacecraft. Pandora is on the left, and Epimetheus is on the right.

Faint, ghostly spokes dapple the dark side of Saturn A ring as the planet shadow makes a sharp diagonal cut across this image from the Cassini spacecraft.

Saturn ... Four Years Later

Epimetheus floats in the distance below center, showing only the barest hint of its irregular shape. Pandora hides herself in the ringplane, near upper right, appearing as little more than a bump

Sweeping Ring View

The Cassini spacecraft spies Pan speeding through the Encke Gap, its own private path around Saturn

Out of Darkness

While NASA Cassini spacecraft was pointed to study Saturn F ring, it happened to catch a globular star cluster passing through the camera field of view. Animations are available at the Photojournal.

Shadow of the Giant

Saturn's C ring isn't uniformly bright. Instead, about a dozen regions of the ring stand out as noticeably brighter than the rest of the ring, while about half a dozen regions are devoid of ring material. Scientists call the bright regions "plateaus" and the devoid regions "gaps." Scientists have determined that the plateaus are relatively bright because they have higher particle density and reflect more light, but researchers haven't solved the trickier puzzle of how the plateaus are created and maintained. This view looks toward the sunlit side of the rings from about 62 degrees above the ring plane. The image was taken Jan. 9, 2017 in green light with the Cassini spacecraft's narrow-angle camera. Cassini obtained the image while approximately 194,000 miles (312,000 kilometers) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 67 degrees. Image scale is 1.2 miles (2 kilometers) per pixel. https://photojournal.jpl.nasa.gov/catalog/PIA20529

Crescent of Saturn

Artist Concept of Particle Population in Saturn Magnetosphere

NASA Cassini spacecraft captures a couple of small moons in this image taken while the spacecraft was nearly in the plane of Saturn rings.

This psychedelic view of Saturn and its rings is a composite made from images taken with the Cassini spacecraft wide-angle camera using spectral filters sensitive to wavelengths of infrared light

Although the embedded moon Pan is nowhere to be seen, there is a bright clump-like feature visible here, within the Encke Division. Also discernable are periodic brightness variations along the outer right side gap edge

This image, taken by NASA Cassini spacecraft, shows the shadows of two moons as they appear on Saturn, above and below the plane of the planet rings.

The Cassini spacecraft spies an intriguing bright clump in Saturn F ring. Also of interest is the dark gash that appears to cut through the ring immediately below the clump

Straightening Out the Kinks

The Cassini spacecraft looks toward the innermost region of Saturn rings, capturing from right to left the C and B rings. The dark, inner edge of the Cassini Division is just visible in the lower left corner

Mimas in Hiding

The Cassini spacecraft gazes down through the dark side of Saturn rings toward the softly glowing planet. The night side southern hemisphere is lit by sunlight reflecting off the opposite side of the rings

Slightly Sideways Saturn

Two pairs of moons make a rare joint appearance. The F ring shepherd moons, Prometheus and Pandora, appear just inside and outside of the F ring the thin faint ring furthest from Saturn as seen by NASA Cassini spacecraft.

Cloud Detail

Scientists can use images such as this one from NASA Cassini spacecraft to learn more about the nature of the particles that make up Saturn rings.

Crossing Dione

Saturn rings are dark and elusive in this view from high above the ringplane, but their shadows on the planet give them away

NASA Cassini spacecraft images dark spokes on Saturn B ring. Spokes are radial markings on Saturn rings that continue to interest scientists, and they can be seen here stretching left to right across the image.

Held in gravity embrace, Saturn darkened, icy rings encircle the clouded gas giant

Saturn moons Daphnis and Pan demonstrate their effects on the planet rings in this view from NASA Cassini spacecraft. Daphnis, at left, orbits in the Keeler Gap of the A ring; Pan at right, orbits in the Encke Gap of the A ring.

Small Worlds of Saturn

Spiral Density Waves

Keeler Moon and Waves

Out of the Shadow

The rings are awash in subtle tones of gold and cream in this view which shows the outer B ring, the Cassini Division and the inner part of the A ring

F Ring in Between

A Capital Storm

Scrambled Edge

Graceful Lanes of Ice

Satellite Trio

Saturn casts its shadow on the rings in this NASA Cassini spacecraft image that also shows how the rings reflect sunlight onto the dark side of the planet. Here Saturn appears dimly illuminated by this ringshine.

Ghostly spokes in Saturn B ring continue to put on a show for NASA Cassini spacecraft cameras in this recent image. The spokes, believed to be a seasonal phenomenon, are expected to disappear as Saturn nears its northern hemisphere summer.

Looking Through the Rings

Mimas Seeking Solitude

The Moons are the Stars

A bright spoke extends across the unilluminated side of Saturn B ring about the same distance as that from London to Cairo. The background ring material displays some azimuthal i.e., left to right asymmetry

Darkside Lights

New Rings for Cassini Division

Behind the Veil

Sculpting the F Ring

Shadow and Shade

The Face-off

Ring Disrupted

Petite Moon

Two moons hover above the rings from this perspective, Enceladus 313 miles or 504 kilometers across, at left, and Janus 111 miles or 179 kilometers across, at right as seen by NASA Cassini spacecraft.

Pandora Gets Kinky

Cassini stares toward the night side of Saturn, seen here on the right, as the active icy moon Enceladus glides past

Three of the small worlds that hug the outer edges of Saturn immense ring system are captured in this Cassini spacecraft portrait

Ring Tableau

Finally . . . Spokes!

Two moons, Rhea and Dione, join the planet and its rings in this view from NASA Cassini spacecraft. Rhea and Dione are respectively the second and fourth largest moons of Saturn, but they are tiny compared to the planet.

Moon-Made Rings

This Cassini spacecraft view shows details of Saturn outer A ring, including the Encke and Keeler gaps. The A ring brightens substantially outside the Keeler Gap

Azimuthal Variability

The Agitator

Saturn fine, innermost rings are seen silhouetted against the southern hemisphere of the planet before partially disappearing into shadow

Evidence of Collision

Many Faces of the C Ring

It difficult to get a sense of scale when viewing Saturn rings, but the Cassini Division seen here between the bright B ring and dimmer A ring is almost as wide as the planet Mercury as seen by NASA Cassini spacecraft.

Bright Arc of Ice

Saturn bright ringlets seen here are populated with microscopic icy particles and are among the brightest features in the rings at high phase angles

Peering over the shoulder of giant Saturn, through its rings, and across interplanetary space, NASA Cassini spacecraft spies the bright, cloudy terrestrial planet, Venus.

Clumpy Construction

This colorized mosaic from NASA Cassini mission shows an infrared view of the Saturn system, backlit by the sun, from July 19, 2013.

Saturn B ring is spread out in all its glory in this image from NASAS Cassini spacecraft. Scientists are trying to better understand the origin and nature of the various structures seen in the B ring.

A bright clump of material within Saturn tenuous F ring stands out near the center top of this NASA Cassini spacecraft image.

Saturn Faint Inner D-ring