Cassini-Huygens Working at Saturn
Data | Overview of Saturn rings and shepherding moons system. click to a larger picture. (click to a chart with data in kilometers) |
Saturn
Saturn is the sixth planet from the Sun and the second largest -after Jupiter- in the solar system. Like Jupiter, Saturn is a gas giant with gas in layers surrounding a solid small core. The weather activity at Saturn is not as pronounced than the one seen at Jupiter although winds are reaching much stronger speeds at the ringed planet. The most distinctive trait of Saturn is obviously its ring which is a fine show as seen from Earth. Saturn has a vast system of satellites. The ringed planet takes 29 years to complete its orbit. see some data about Saturn
Rings
Cassini will certainly produce new data about Saturn's rings. Saturn and its ring system serve as a miniature model for the proto-planetary disk which surrounded the early Sun and where the planets originated. Detailed knowledge of the dynamics of interactions among Saturn's rings and some of Saturn's moons will provide valuable data for understanding how the solar system's planets evolved. Generally, rings of gas giants seems to have been yielded by small close moons being torn apart by tidal waves or by an asteroid or comet collision. Or they might result from debris which were prohibited to form a moon by the gas giant's gravity. Debris in case of a disruption or a collision stretched in planet's equatorial plane. Rings are thought to eventually disappear on a time span of several billion years as debris are reduced to dust and dust swept away. Ring disappearance is a slow process: some particles or debris may re-accrete into moons or moonlets or closest moons to the planet may capture material from the ring. Another idea is that ring disappearance might be swift, about a few hundred million years. Most of rings seem young: under a few hundred million years (which is very few compared to an age of 4.5 billions for their planets). Most planets might form a ring provided enough material is present
Saturn's rings are believed to be 100 million years old (some think their history may span several hundred million years) and are thought to originate from collisions occurred at Saturn's moons or from other bodies which were disrupted by the planet's gravitational field. It is believed too that the planet might have had several succeding rings systems since Saturn formed 4.5 billion years ago. The Voyager missions saw so-called 'spokes' in the B ring, features which radiates along the ring at some sight angles, as the nature of them is still ill-known. Saturn's ring features three main zones: an outermost part of the ring called "A ring", a middle (and brightest) part of it called "B ring", and an innermost (and fainter) part called "C ring". A 200 mi (325 km) wide gap named Encke gap is found near A ring outer part. A 2980 mi (4800 km) division, named Cassini division, is separating A and B ring. B ring outer part is in resonance with the moon Mimas and the moon Mimas is responsible for the Cassini division. Ring system is about 171,000 mi wide (480,000 km) in its greater extension as, more generally, it contains 7 main rings, namely, from the planet outward, the D, C, B, A, F, G and E rings, which were labeled in the order they were discovered. Rings are roughly 200 meters thick except A-ring which is about 50 m and C-ring which is about 10 m. The ring, in no place, is thicker than a 2-story building! Would you compress all the material that makes up the rings into a single body, you would get a moon roughly 80 percent the size of Enceladus (which is 314-mile wide (505 km)). As they appear to be solid structures, rings are actually composed of billions of individual particles, each one orbiting the planet on its own path. Such components are either frozen dust particles, grains, pebbles, or ice blocks and range in size from grains of sand to a house. Some nearby moons are gravitationally linked to the ring system, resonating about particles or shepherding them, creating wavelike patterns, in the way some water ridges are seen at a pound. Particles bumping into each other due to such interactions brings to variations in ring particle concentration, hence patterns like waves or wakes. The overall mechanism of the ring structure is still unknown however. picture © site 'Amateur Astronomy'
OperationsImages en Route
Saturn
Rings
Shepherding Moons
Grand Finale
->More Hints About Saturn's Moons Formation!
Disturbances within the rings might be at the origin of the formation of Saturn's moons, like such a event seen in April 2014 as a new moon then leaves the rings to turn a real moon, possibly merging with other moons on the way. Some objects, no more than half a mile in size, are so small that they are transient only. Theory holds that Saturn long ago had a much more massive ring system
capable of giving birth to larger moons. The formation of moons eventually depleted the rings down to their current state. The moons of Saturn which formed earliest turned the largest and moved the farthest away. Data on how the rings cooled during the time after the equinox -which was the time when the Cassini mission arrived in the Saturnian system- provided insights about the nature
of the ring particles as the middle of the A ring did not cool as expected. Ring particles generally are fluffy on the outside, like fresh snow and made of regolith. Ring particles usually spread out and
become evenly distributed on a timescale of about 100 million years. The A ring anomaly suggest there are larger particles there, like the result of a pre-existing moon
->UV Overview of Saturn's World (Nov. 2004)
Last Nov 8, Larry Esposito, of the Laboratory for Atmospheric and Space Physics, CU-Boulder, gave a first general overview of data beamed back by Cassini based on the work of the UVIS (Ultraviolet Imaging Spectrometer) instrument. Larry Esposito is the principal investigator for the instrument. The UVIS is revealing a turbulent world at Saturn. Moonlets inside the ring system (and maybe more specifically yet unseen moons at the E ring) are colliding, releasing ice particles. Saturn's radiation belt is liberating the oxygen atoms at such ice grains. The atoms, in turn, are feeding a gigantic cloud of ice and atoms derived from water around Saturn. Detailed approach of the ring system has shown in the ultraviolet that the ring has been the place to the recent destruction of small, 12-mile wide (20 km) moons and that various collisions and meteoroid bombardment are occurring there. Hence from pure ice at the origin, the ring was contamined. This yields dust as wave motions inside the ring are layering such dust on the ice particles, making the ring darker. Such events are thought to have occurred during the last 10-100 million years. On the other hand the solar wind, when it reaches speeds of up to 250 miles per second (400 km/s), is generating more intense auroras at Saturn's poles. "Instead of a quiet panorama, UVIS sees rapidly changing phenomena, including interactions between the rings, moons, radiation belt, solar wind and the planet Saturn," said Larry Esposito, of the Laboratory for Atmospheric and Space Physics, CU-Boulder, the principal investigator for the instrument
Esposito at last is confirming that the moon Phoebe -which was visited by Cassini on last June 11th, 2004- surely was formed outside the Saturn's system. Its most likely place of origin is the Kuiper Belt where thousands of icy bodies are found, leftovers of the solar system formation. Phoebe has a retrograde motion. It probably was captured by Saturn during the planet's formative years
On the other hand the ring is considered to be a few hundred million years old and to be the result either of a moon blasted off by an impactor or of an external body which ventured too close to the planet and was ripped apart by the tidal forces
 | "Surface" weather at Saturn provided by deep red spots? picture NASA/JPL/Space Science Institute |
New Findings: Rings, Small Moons, Saturn (Feb. 2005)
The interaction ring-moons provided reliable masse values for the small Atlas and Pan. Such small moons are porous or even rubble piles. Prometheus and Pandora, the F-ring sheperding moons are likely of the same kind. An additional small moon, Polydeuces, about 3 mi (5 km) across, was found. It's the trailing Trojan of Dione. Saturn is the only planet moons of which have been found to have two moons (Dione and Tethys) to have Trojan. On the other hand, the orbits of several Saturn's small moons have been refined, of them the one of Pan, which orbits inside the Encke Gap, and which was found eccentric and slightly inclined. As far as the ring is concerned, several additional, small, faint ones have been found in the well-known gaps as some small moons -still to be found- might be involved in their behavior. see a dedicated page. The atmosphere of the ringed planet has been further probed. The main finding is that the strong winds at Saturn seem to be powered by a convection motion coming from the interior as, generally, the weather patterns at Saturn might be linked to deeply-buried kinds of red spots yielding small patterns at the "surface", these ones in turn melting and evolving into the usual atmospheric features like the ovals and the eastward and westward currents. Winds are varying according to the altitude. The magnetosphere of Saturn has been found to be Jupiter-like although, at some locations, it ressembles water-based plasmas found at comets
Cassini Performed its First Radio Occultation of the Ring (Jun. 2005)
In the first of many such observations Cassini will be conducting over the summer, the spacecraft was able to provide the first detailed study of Saturn's ring system through a radio occultation. A radio occultation is the technique by which Cassini sends a radio signal to Earth, through the rings. How the strength of the radio signal is affected gives hints about the rings. The denser a ring is, the weaker the signal received. It's such an operation which helped to map the distribution of the amount of ring material and determine the ring particle sizes. This May 3, 2005 radio occultation, on the other hand, was the first ever to use three radio signals of different frequencies (Ka, X and S; 0.94, 3.6, and 13 centimeter wavelength respectively) which were transmitted simultaneously from Cassini to the NASA's Deep Space Network (DSN) receiving stations, with ring particles of different sizes affecting each frequency differently
 | The radio ring vision (bottom) has been constructed from the measured optical depth profiles rendered by the Ka, X, and S-band radio wavelengths. It has a resolution of 6 mi (10 km) and it's compared to a visible view of the ring system (top). Purple (most of the B ring and the inner portion of the A ring) is where there is a lack of particles less than 2 inches (5 cm) in diameter. Green and blue is where there are particles of sizes smaller than 2 inches (5 cm) and 1/3 of an inch (1 cm) respectively (that is in the outer A ring and most of the C ring). The saturated broad white band near the middle of ring B is the densest region of ring B. click to a larger view. picture NASA/JPL |
The inner and the outer parts of the B ring are containing hundred of mile-wide (hundred of km) rings with a thick 3,100-mile wide (5,000 km) core (with several bands with a density of ring material which is nearly 4 times as dense as that of A ring and about 20 times that of the C ring). The B ring, despite such a density, has been seen containing a major density wave. By contrast, the A ring has a relatively flat structure. The A ring was found too to have more than 40 wavy features, many near its outer region. Such "density waves" are caused by the gravitational interactions with nearby moons. The C ring has a wavy structure with many dense, narrow and sharp-edged ringlets in its outer part. Generally, particles size has been estimated to vary up to many meter-wide at the upper end, everywhere, down to less than 2 inches (5 cm) in the C ring and the outer A ring. Particles of about 2 inches (5 cm) or less seem to be scarce in B ring and the inner A ring. Particles in the A ring generally typically range in size from several yards (meters) across down to half-inches (centimeters)
 | numerous density waves have been seen in the A ring. The color code, here, is red is for regions where there is a lack of particles less than 2 inches (5 cm). Green and blue are for regions where there are particles of sizes smaller than2 inches (5 cm) and 1/3 of an inch (1 cm). click to a larger view. picture NASA/JPL |
Cassini Completed its Ring Campaign (Sep. 2005)
The ring phase of the Cassini mission's work has brought its crop of results (from the outside to the interior of the ring):
- the ring generally: a thermal map of the ring has allowed to understand that the ring particles are spinning in the order of several times per orbit to less than one time, that is, generally, slowly compared to their orbital periods of 6 to 14 hours. The outer A ring might contain smaller, or more rapidly rotating ring particles
- G-ring: a fait arc has been seen along the ansa of the G ring
- F-ring: 1) clump-like features in the F ring are either just transient products of interactions with the shepherding moons or moonlets of themselves. Some of these features were, for example, provisionally named S/2004 S3 and S/2004 S6. 2) a spiral structure is contained in the F-ring, which appears to originate from material episodically ejected from the core of the F-ring and then sheared out due to the different orbital speeds followed by the constituent particles. It might be that the ejection of the material be due to moons crossing the F-ring and spreading its particles
- A-ring: clumps features exist too in the outer part of the A ring
- D-ring: 1) in the innermost part of Saturn's ring, the D-ring, two views taken 25 years apart by Voyager 1 and Cassini are showing that one ringlet (the D72) has moved 125 mi (200 km) inwards and decreased in brightness by more than an order of magnitude relative to the other ringlets. Such a variability of a part of the ring is considered an important contribution to the understanding of the dynamics of the ring. 2) a close-up view of the D-ring is showing a periodic wave-like structure with a wavelength of 19 miles (30 km) which is due to the gravitational interaction of Saturn or of its magnetic field
click on the picture above for views illustrating the passage. pictures NASA/JPL/Space Science Institute except arc in the G-ring: NASA/JPL/University of Colorado
Rings are Not a Temporary Feature, Young, Albeit Always Present (Dec. 2007)
Recent studies are showing that Saturn's rings aren't a temporary feature which would be headed to dissipate over time, as even when ring particles fragment into smaller ones, those broken particles however tend to aggregate back together, thus maintaining the overall ring structure. The rings, eventually, might not be older than 100 million years ago, and triggered by a moon shattered by a comet, instead of the 4.5 billion years thought until now. But Saturn seems, on another hand, to have had rings all along its history, with such events, and recombination of material inside the rings, to have occurred regularly and all the time. The ring, at last, should thus keeps existing for billion years more. Temporary aggregations of particules in the rings, are forming, like in the F-ring, such objects of a size between 30 yards and 6 miles across (27 meters-10 km)
Materials in The Saturnian System Dating Back to The Origins of The Solar System! (May 2013)
Though they are tinted on the surface from recent cosmic pollution, Saturn, its rings and moons are dating back more than 4 billion years, or the time when planets of our solar system began to form out the protoplanetary disk, or nebula. Any water ice in the Saturnian system also dates to that time as Saturn is lying beyond our Sun's snow line. Patina on inner rings and closer moons originate from water-ice spray from the geyser moon Enceladus as the farther a ring or a moon, the redder due to Phoebe shedding its dust. The reddish hue of the B ring is likely due to a rain of meteoroids from outside the system, as that could be oxidized
iron -rust- or polycyclic aromatic hydrocarbons. The reddish color of Prometheus matches the fact that the moon built from nearby ring particles, a exception in the system
Material Mass in The B Ring and Rings' History (January 2016)
The B ring is the brightest of Saturn's rings when viewed in reflected sunlight but the brightest and most opaque generally, which is consistent with previous studies that found similar results for Saturn's other main rings. By 2016, Cassini scientists have demonstrated that there is less material in the B ring than thought, basing upon data from a series of observations by Cassini as it peered through the rings toward a bright star. Scientists identified spiral density waves in the rings, which are fine-scale ring features created by gravity tugging on ring particles from Saturn's moons, and the planet's own gravity. Each wave depends directly on the amount of mass in the part of the rings where the wave is located, as regions with the same amount of material can have such different opacities. That is still ill-explained. Such research about the mass of the rings has important implications for their age. A less massive ring would evolve faster than a ring containing more material, becoming darkened by dust from meteorites and other cosmic sources more quickly. Thus, the less massive the B ring is, the younger it might be -- perhaps a few hundred million years instead of a few billion. Albeit the mass of the B ring is unexpectedly low, some parts of it are up to 10 times more opaque than the neighboring A ring (the B ring however is still thought to contain the bulk of material in Saturn's ring system. The global mass of Saturn's ring should be assessed soon. While all the giant planets in our solar system (Jupiter, Saturn, Uranus and Neptune) have ring systems of their own, Saturn's are clearly different. Explaining why Saturn's rings are so bright and vast is an important challenge in understanding their formation and history, which needs a detailed study of the density of material packed into each section of the rings to ascribe their formation to a physical process
Following pictures are showing how Cassini imaged Saturn since November 2002 as he was nearing the ringed planed. One picture of Jupiter had been snapped by Cassini in December 2000. pictures based upon pictures courtesy NASA
 | This picture taken on May, 4th 2004 from 18.5 million miles (29.7 million km) is showing Saturn atmosphere and the neat projected shadow of the planet unto the rings. picture courtesy NASA/JPL/Space Science Institute |
 | Saturn as seen from 16.3 million miles (26.3 million km) is showing too the icy moon Enceladus right of Saturn's south pole. picture courtesy NASA/JPL/Space Science Institute |
 | Saturn's south pole seen on May, 20th 2004 from 13.7 million miles (22 million km). Lightly colored clouds are seeing dotting the region as Saturn's atmosphere might appeared more mottled than thought. picture courtesy NASA/JPL/Space Science Institute |
 | Saturn's atmosphere: troposphere, stratosphere, winds. more. picture courtesy NASA/JPL/Space Science Institute |
 | This mosaic of images taken from a ground observatory, Feb. 4, 2004, is showing the upper troposphere of Saturn and particularly how temperatures there are abruptly increasing near 70° S (light orange area near the pole) as the pole itself is a hot spot. Note that ring particles are cooler (lower left) when exiting from the planet's shadow, reaching their maximum before entering back into the shadow (lower right). picture courtesy NASA/JPL |
-> (by order of discovery)
Cassini Joins Hubble to Tell More About Auroras at Saturn
 | thumbnail to the aurora at Saturn; one hour between the pictures (pictures enlarged by our site) (left), and a simultaneous view of Saturnian northern and southern auroras (right). picture NASA/JPL/University of Colorado (left) and NASA/ESA/STScI/University of Leicester (right) |
Saturn auroras have been found of a species of their own on the basis of data by Cassini and Hubble. Up to now, Saturn's auroras were believed to be a cross of those seen at Earth and at Jupiter. Saturn's auroras' brightenings have been seen lasting days (10 mn at Earth) as they are lasting at least one hour. The aurora oval may not (like at Earth, the planet rotating under it) or may (like at Jupiter) rotate along with the planet and, most of all, auroras are not linked to the direction of the solar wind's magnetic field as they are are at Earth (where the magnetosphere let the solar wind leak in when its polarity is South see more) but might better be linked to shock waves (pressure) in the solar wind and electric fields. Oddly the aurora oval, although brightening during periods of higher activity, is even shrinking in diameter at that moment. At last, magnetic storms are increasing in intensity at the day-night boundary as auroras are brighter there, or the oval may have its ends not connected sometimes. On Earth, aurora is mostly from oxygen atoms and nitrogen molecules. On Saturn, it's from emissions of molecular and atomic hydrogen. Saturnian auroras do not only work like the one at the Earth, with particles of the solar wind channeled by the magnetosphere into planet's poles where they interact with electrically charged gas
(plasma) in the upper atmosphere and emit light, as they further may be produced too due to electromagnetic waves resulting from the passage of Saturn's moons through the planet's magnetospheric plasma. Saturnian auroras clearly vary significantly over the course
of a Saturnian day, which lasts around 10 hours 47 minutes. By noon and midnight
midnight, the aurora
can be seen to brighten significantly for periods of several hours, suggesting
the brightening is connected with the angle of the Sun. Other features likely are more due to the orientation of Saturn's magnetic field as they are reappearing at the same time and same place
on the following day. Glow of auroras may be observed glancing by about 600 miles (1,000 kilometers) above Saturn's cloud tops. Astronomers discovered some subtle differences between the
northern and southern auroras. The northern auroral oval is slightly smaller and more intense
than the southern one, implying that Saturn's magnetic field is not equally
distributed across the planet; it is slightly uneven and stronger in the North
than the South
Lightning Seen At Saturn!
Cassini, by August 2009, has spotted lightning on Saturn! The flashes lasted less than one
second. The images show a cloud as long as 1,900 miles (3,000 kilometers) across
and regions illuminated by lightning flashes about 190 miles (300 kilometers) in
diameter. The data suggest extremely powerful storms with lightning that
flashes as brightly as the brightest super-bolts on Earth. What's interesting is that the storms are
the storms at Saturn as powerful -- or even more powerful -- at Saturn as on Earth, albeit occuringthey occur much less frequently, with usually only one happening on the
planet at any given time. They can last too for months like that occurred during a storm
that churned from January to October 2009 and lasted longer than any other
observed lightning storm in the solar system. A belt around the
planet where Cassini has detected radio emissions and bright, convective clouds
earned the nickname 'storm alley'. Cassini too recorded the crackle of radio waves emitted when lightning
bolts struck
The Mystery of Saturn's Rotational Irregularities Explained!
Like at Jupiter, Saturn rotational period can not be measured due to a lack of any fixed reference at their 'surface'. Astronomers used instead the so-called 'Saturn Kilometric Radiation', a peaking, radio emission specifity of Saturn magnetosphere supposed to occur at each rotation. Saturn signals however were found to significantly vary, hindering any accurate foretale of Saturn's rotation. Latest findings in late 2010 by the Cassini mission now have elucidated that mystery, which is a mix of interaction between plasma injections, electrical currents and Saturn's magnetic
field.
Saturn's magnetosphere is partly blown back, the side away from the Sun, in a comet-like shape. Enceladus, one of Saturn's moons is sending its icy particles into a torus and are magnetized into a dense and cold plasma. That plasma, a way or another, causes the magnetosphere to snap back at some point. That collapse in turn kick off hot, enourmous, plasma clouds, which rotate inside the magnetosphere and are increasing electrical currents and magnetic field distortions. Magnetosphere, in response to pressure, is periodically 'exploding' and distorting the magnetic field lines. That phenomenon is causing the distortion of Saturn's kilometric radiation as it the particles plasma likely too is braking the magnetic field rotation self. The radiation, generally, is also linked to the planet's aurora which might further intricate the variation with numerous small radio sources moving along magnetic lines in the auroral regions and emission are further complicated by interaction between the radio waves themselves, which processes also are observed about radio emissions generated by terrestrial auroras. The influence of Enceladus, on another hand, is more or less pronounced according to the seasons in the Saturnian world, as the field of Saturn is further complicated by that Enceladus seems too to generate an assymetry in it!
Data from 2011 have shown that the variation in radio
waves controlled by the planet's rotation is different in the northern and
southern hemispheres. Radio waves emanating from near the north pole have a period of around 10.6
hours and those near the south pole of around 10.8 hours, with a crossover point by some 7 or 9 months after Saturnian equinox. Such features more likely come
from variations in high-altitude winds in the northern and southern hemispheres and not from a difference in rotation between both hemispheres. Saturn emissions thus are much different from those at Jupiter. The
northern and southern auroras on Saturn further wobbled back and forth in latitude in a
pattern matching the radio wave variations. The radio signal and aurora data are complementary because they
are both related to the behavior of Saturn's magnetosphere. Saturn's magnetic field over the two
poles also was proved to wobbled at the same separate periods as the radio waves and the aurora. The rain of electrons into the atmosphere that produces the auroras also
produces the radio emissions and affects the magnetic field
Saturn's Position Accurately Pinpointed!
By early 2015, scientists have paired NASA's Cassini spacecraft with the National Science
Foundation's Very Long Baseline Array (VLBA) radio-telescope system to pinpoint
the position of Saturn and its family of moons to within about 2 miles (4 kilometers) improving knowledge of Saturn's orbit. That will help enhance precise navigation of
interplanetary spacecraft and help refine measurements of the masses of solar
system objects
 | Saturn's magnetosphere. The hydrogen emission seen here is giving some hints about magnetosphere general shape. Further studies by Cassini showed that, as Saturn's magnetosphere has a classical, comet-like shape, a 'ring current' is part of Saturn's magnetosphere elements, surrounding the rings, at a distance of about 5 times farther, near the orbit of Rhea. Interactions occur between Saturn's dynamic population of hot energetic ions and the clouds of cold, high-speed neutral atoms out from a region Titan 43,496 miles (70,000 km) in diameter. picture courtesy NASA/JPL/John Hopkins University |
 | This view of Saturn is showing the planet on July, 17th 2004 as Cassini is on its initial orbit in Saturn's system. Image was taken from 3.6 million miles (5.8 million km) away. picture courtesy NASA/JPL/Space Science Institute |
 | Polar details at Saturn: bright clouds and dark spots. Such features are reminding of what may be seen at the polar regions of Jupiter. picture courtesy NASA/JPL/Space Science Institute |
 | Due to being farthest from the Sun, Saturn has its clouds forming lower in its atmosphere. Hence the banded appearance of cloud patterns which are so familiar at Jupiter occur here deeper, making them less visible. This enhanced-color view, increasing contrast, makes Saturn's bands easier to see. picture courtesy NASA/JPL/Space Science Institute |
 | A view of Saturn bands in the infrared. View taken on Sept 13 2004 (preparatory trajectory). picture courtesy NASA/JPL/Space Science Institute |
 | A view of Saturn bands in the infrared. View taken on Sept 9 2004 (preparatory trajectory). The ring is overexposed. picture courtesy NASA/JPL/Space Science Institute |
 | This methane-filtered view is showing high haze layers in the atmosphere of Saturn. A picture filtering methane at Saturne shows dark regions where light travels deeper into the atmosphere (passing through more methane) before reflecting and scattering off of clouds and then heading back out of the atmosphere. In such images, the deeper the light goes, the more of it gets absorbed by methane, and the darker that part of Saturn appears. picture courtesy NASA/JPL/Space Science Institute |
 | A turbulent boundary between two latitudinal bands (seen in the infrared). picture courtesy NASA/JPL/Space Science Institute |
 | Various atmosphere features are seen in this infrared view taken on September 25, 2004. Compared to what is seen at Jupiter such atmosphere's blown-up features are consistent with the higher winds at Saturn (image taken on September 25th, 2004). picture courtesy NASA/JPL/Space Science Institute |
 | Many narrow cloud streaks, with a filamentary structure are the other feature of gas giants' atmosphere. Such clouds extend and curl over great distances maintaining their integrity, as they don't mix with neighbouring air parcels. This is called "two-dimensional turbulence". Clouds behave like fluids in a thin, soapy or oily film floating on water. Such cloud layers are thin and they don't participate to the three-dimensional turbulent systems. picture courtesy NASA/JPL/Space Science Institute |
 | Several small, dark storms in the southern latitudes, pointing to storm activity, has been prevalent since before Cassini arrived in orbit. The globe of Saturn and the ring system are playing with the light coming from the Sun, as the upper part of Saturn's night side is dimly lighted by the light reflecting off the illuminated side of the ring, as the lower part is dimlier still lighted by the light managing to pass through the rings. picture courtesy NASA/JPL/University of Arizona/Space Science Institute |
 | Saturn's northern hemisphere reached its summer solstice in mid-2017, with the solstice on May 24, bringing continuous sunshine to the planet's far North. picture courtesy NASA/JPL-Caltech/Space Science Institute |
 | A mighty storm is seen on the nightside of Saturn about Jan. 25, 2006. Its dimensions are 2,175 miles (3,500 km) North-South, as it was featuring lightnings, the sound of which Cassini was able to record. picture courtesy NASA/JPL/Space Science Institute |
->Using the 5-micron wavelength of its visual and infrared mapping spectrometer allowed Cassini this view of cloud located at 19 mi (30 km) underneath the clouds usually observed on Saturn. They are interestingly alike what may be seen at Jupiter in the visible and might hint to a similar structure in both the first gas giants, with the upper, speedy winds of Saturn smoothing of sort these well-defined shapes
 | An observation of Saturn in the 5-micron wavelength by Cassini's visual and infrared mapping spectrometer allowed this view of cloud located at 19 mi (30 km) underneath the clouds usually observed on Saturn. NASA/JPL/University of Arizona |
 | Doughnut-shaped clouds North, swirls and cloud cells at the equator and lanes of wispy clouds connected to cloud cells South. NASA/JPL/University of Arizona |
 | This view is finely showing how the Saturn's globe is impressive. The ring is seen from below. NASA/JPL/Space Science Institute |
 | Such views are showing how Saturn's atmosphere is similar to that of Jupiter, with dark belts, bright zones, turbulences, spots, ovals, dark round storms. The opposing East-West flows of cloud bands are the main influential pattern of these two gas giants. more. site 'Amateur Astronomy' with original pictures NASA/JPL/Space Science Institute |
 | This storm surrounded by a halo of bright clouds -being bright at each wavelength- was captured by Cassini on Jan. 24, 2006. A band of latitude near 30°, generally speaking, is the "storm alley" since this is where two high-speed jet winds moves at different speeds generating a wind shear (picture in visible light). The storm alley is also where ovals are found. courtesy NASA/JPL/Space Science Institute |
 | Fine striations hint to steadiness as larger-scale flows are the evidence of vortex motions. site 'Amateur Astronomy' with original pictures NASA/JPL/Space Science Institute |
 | This view in the infrared is showing bright features which might be places of convection, that is places where sufficiently warm air at deeper levels rises to upper levels. The picture covers from the latitude 18° South to the latitude 50° South. site 'Amateur Astronomy' with original pictures NASA/JPL/Space Science Institute |
 | Clouds seen 3D. Picture is in the visible, North is upper right. picture courtesy NASA/JPL/Space Science Institute |
 | NASA's Cassini spacecraft gazed toward the northern hemisphere of Saturn to spy subtle, multi-hued bands in the clouds there. This view looks toward the terminator -- the dividing line between night and day -- at lower left. Some vertical relief is apparent in this view, with higher clouds casting shadows over those at lower altitude. The image was acquired at a distance of approximately 700,000 miles (1.1 million kilometers) from Saturn. picture based upon a picture courtesy NASA/JPL-Caltech/Space Science Institute |
 | Another 3D view of Saturn's clouds (image in the visible, Jan. 23, 2006). picture courtesy NASA/JPL/Space Science Institute |
 | A view in the infrared (corrected to visible by our site) is showing the vertical extent of cloud bands. picture courtesy NASA/JPL/Space Science Institute |
 | The Saturnian upper atmosphere -which is seen, here, through a part of the ring- is displaying, on this picture, puffy clouds and long filamentary streamers. The streamers are similar to anvil-shaped Earthly cirrus clouds that extend downwind of thunderstorms. The image is in the infrared. picture courtesy NASA/JPL/Space Science Institute |
 | Other clouds seen 3D in this oblique view of the northern hemisphere. Picture in the visible wavelengths range. site 'Amateur Astronomy' based on a picture NASA/JPL/Space Science Institute |
 | Clouds structures seen in the ring's shadow. site 'Amateur Astronomy' based on a picture NASA/JPL/Space Science Institute |
 | A shallow banded structure is seen at the South pole. The fact that the characteristic high-latitude, mottled, turbulent structure is seen underneath is suggesting that the banding is shallow (picture dated April 23, 2005). picture courtesy NASA/JPL/Space Science Institute |
 | Atmospheric waves are seen here along the planet's could as (lower right) at a higher altitude than the clouds. In the later case, such waves are of a smaller scale. picture courtesy NASA/JPL/Space Science Institute |
 | As the heat of the interior of Saturn is making its way to the surface under the form of infrared radiation, it's silhouetting the structures of the clouds of the planet. picture courtesy NASA/JPL/NASA/JPL/University of Arizona |
 | As that view in the near-infrared is showing a Saturnian aurora at one of Saturn's poles (green), it is also revealing how thermal radiation coming from the interior of the planet (red) is silhouetting from underneath the stormy dark spots and clouds bands, underlining the deep weather systems and circulation currents. picture courtesy NASA/JPL/University of Arizona/University of Leicester |
 | This view is revealing (left; in the night of Saturn; and barely seen too on the lit side, under the haze and high layers) how a far more turbulent, Jupiter-looking weather activity is seen at Saturn under the haze and the high layers of clouds. picture courtesy NASA/JPL/University of Arizona |
 | Another view of how the deep layers of Saturn are akin to the weather events seen at Jupiter. View in the infrared. A thorough study of Saturn's atmosphere is helping scientist to tell new views about how the bright and dark band system and the jet streams and eddies are working at Saturn -and likely at Jupiter too! The latest studies by Cassini are showing how it's the small eddies either side of the main jet streams which are providing momentum to those -and not the opposite like thought! As the bright bands were thought to be regions where air rises and the dark ones where it's sinking, the fact that the Cassini scientists observed thunderstorms in the dark bands only, likely means that those are regions of rising air instead -and the opposite (and likely the same at Jupiter). Turbulent jet streams, regions where winds blow faster than in other places, churn East and West across Saturn's atmosphere. Such wavy structures are powered through the heat from within the planet. Internal heat from the planet is stirring up water vapor from Saturn's interior. That water vapor condenses in some places as air rises and releases heat as it makes clouds and rain. This heat provides the energy to create eddies that move air back and forth at the same latitude. Where most of the Sun's heating occurs, at the higher altitudes, eddies are weak as they are stronger deeper in the atmosphere. Those eddies also accelerate the jet streams like rotating gears driving a conveyor belt. Most jet streams most eastward, some blow westward as they blow in places where the temperature varies significantly from one latitude to another. Jets also occur in places where the temperature varies strongly from one location to another with a disturbance moving warm air into a colder region or vice-versa. Eddies can be weak at the altitude where most of the sunlight heating occurs as eddies can be stronger down deep. picture courtesy NASA/JPL/University of Arizona |
 | Incredible! A lasting cyclon is just located at Saturn's south pole. This view in the infrared is showing the towering walls of it! Amazingly, it's just like a one-eyed Saturn as, in the mythology, Saturn is brother to the Cyclopes, as the hurricane is about 2 to 5 times the size of the hurricanes seen at Earth in height, with a diameter 5,000 miles (8,000 km). picture courtesy NASA/JPL/Space Science Institute |
 | A view of Saturn's south pole vortex which further contains vigorous convective storms, or deep convective upwelling structures seen through the atmospheric haze. The ring outside is similar to the eyewall of a terrestrial hurricane, but much larger. Saturn’s vortex of the south pole is seen in that image at 10 times more detailed than any previous picture and a multitude of features is revealed. Clouds at Saturn are due to convection. Warm gases are rising in the atmosphere of Saturn. Then reaching higher and colder, they condense into clouds. The 'eye' of the storm, like in earthly hurricanes, is composed of warmer gas than the surroundings. picture courtesy NASA/JPL/Space Science Institute |
 | The north pole, as far as it is concerned, features a weather hexagonal feature similar to the polar vortex seen at Earth, as this vortex was first seen by the Voyager missions 26 years ago and before by the Pioneer as it had been at that time that it had been dubbed the 'hexagon.' The hexagon is nearly 15,000-kilometer (25,000-mile) across as it related to high walls of cloud of about 47 miles (75 km) in height. It might be considered a meandering jet stream at 77 degrees north latitude. Both the northern and soutern spots seem related to air masses moving to the poles and sinking downwards, or a extant unusually strong pole-encircling planetary wave extending deep into the atmosphere. Those might be triggered by cumulus clouds swirling around the poles and featuring giant thunderstorms, which yield condensing water hence warmth deep below. The thunderstorms would be composed of ammonium hydrosulfide. Both the vortex and the hexagon-shaped jet stream area are displaying sharp edges. picture courtesy NASA/JPL/University of Arizona |
 | A more detailed, animated view of the north pole hexagone! A large spot is seen inside the hexagon that could be related to a dark spot seen there by Cassini in 2006. An earlier Voyager mosaic showed a large spot outside the hexagon, which existed at least until 1991 before disappearing into the long winter polar night. Seasons might cause a change in color of the region inside the north-polar hexagon on Saturn, in particular the change from a bluish color to a more golden hue may be due to the increased production of photochemical hazes in the atmosphere when the region approaches the summer solstice. The hexagon might act as a barrier preventing haze particles produced outside it from entering during winter. Each latitudinal band represents air flowing at different speeds, and clouds at different heights, compared to neighboring bands. Where they meet and flow past each other, the bands' interactions produce many eddies and swirls. At the Saturn's northern pole nearing summertime, a hexagonal-shaped high-altitude vortex exists, akin to the famous hexagon seen deeper down in Saturn's clouds. The deep hexagon might influence what happens above. The hexagon was discovered by NASA's Voyager spacecraft in the 1980's as it is a long-lasting wave potentially tied to Saturn's rotation, a type of phenomenon also seen on Earth, as in the Polar Jet Stream. picture courtesy NASA/JPL/University of Arizona |
 | The tilted orbits of Cassini have given mission scientists a vertigo-inducing view of Saturn's polar regions with roiling storm clouds and a swirling vortex at the center of Saturn's famed north polar hexagon which is now lightened by sunlight and captured in visible light. Such a structure is similar to a terrestrial hurricane as it uses water vapor like its engine and it features a central eye (in the case of Saturn at 1,250 miles wide) with no, or very low clouds, a eye wall of high clouds and other clouds spiraling around the eye with a counter-clockwise spin in the northern hemisphere. The hurricane at Saturn is spinning four times faster than on Earth and the Saturnian hurricane keeps blocked onto the north pole as scientists believe the massive storm has been churning for years. picture courtesy NASA/JPL-Caltech/Space Science Institute |
 | A side-by-side view of large cyclones at both south (left) and north (right) poles of Saturn with rings of clouds and hazes circling the poles. North Winds reach over 325 mph (523 km/h) as the region is bordered by a hexagon. South features a central eye clear of clouds. Such cyclones likely are powered from convection upwelling from deep inside. picture courtesy NASA/JPL/University of Arizona |
 | That view of Saturn's north pole was captured on April 26, 2017, the day NASA's Cassini spacecraft began its Grand Finale, approaching the planet for its first daring dive through the gap between the planet and its rings. Saturn's north pole keeps benefiting from the northern summer solstice which occurred on May 24, 2017. picture courtesy NASA/JPL-Caltech/Space Science Institute |
 | Saturn's northern polar region shows both the aurora (in blue) and underlying atmosphere (in red). picture courtesy NASA/JPL/University of Arizona |
Rings have been a source of mystery since their discovery in 1610 by Galileo Galilei. How they formed might be that they did along with Saturn, or that they are debris of a former moon that strayed too close to the planet and was ripped apart. In some cases, the reasons for the gaps and ringlets are known; for example, small-sized Pan keeps open the Encke gap. But in other cases, the origins and natures of those are still poorly understood. Scientists are debating the varied structure of the rings, whether they have always appeared this way or if their appearance has evolved over time. Cassini found that the rings are shading the planet during certain seasons and causing all kinds of changes in the atmosphere. Saturn's ring is in its mid-life as it is unlikely to be older than 100 million years and it should have vanished in another 100 million years from now. The rings indeed are being pulled into Saturn by gravity as a dusty rain -- or 'ring rain' -- occurs of ice particles under the influence of Saturn’s magnetic field. Rings likely formed from a comet that wandered too close and was torn apart by Saturn's gravity or by an event that broke up a earlier generation of icy moons. A series of similar impact-generated streaks in the F ring having the same length and orientation, are showing that they were likely caused by a flock of impactors that all struck the ring at the same time. That was caused by streams of material orbiting Saturn itself rather than by one coming from outside the Saturnian system. Close-up ring images brought into focus three distinct textures — clumpy, smooth and streaky — and made it clear that these textures occur in belts with sharp boundaries but the reason why is still unknown. Weak water-ice bands in the outermost part of the A ring, a area highly reflective, were contradictorily found. Water ice is the main component of the ring a no ammonia nor methane ices are found. Rings hold no organic compounds, a surprise, given the organic material discovered flowing from the D ring into Saturn's atmosphere
->A Diffuse, Infrared-Seeable Only Ring Discovered at the Orbit of Phoebe!
A new, very diffuse ring, composed of ice and dust, tilted by 27 degrees relative to the planet's main ring system has been discovered in the infrared by the Spitzer Space Telescope in October 2009! That new ring is lying between 3.7 and 7.4 million miles (5.9-11.9 million km) from Saturn as it features a height of about 20 Saturn's diameters. Phoebe, which orbits at those distances is likely the origin of the particles. That ring further could be the answer for the particles which have dirted a part of Iapetus! The ring, like Phoebe, has a retrograde orbit! The largest known ring around Saturn was found in the infrared by the Spitzer space telescope, at 300 times the diameter of Saturn
->(by order of discovery)
A New Ring at the Orbit of Atlas
A new faint ring has been discovered at Saturn, between the A and the F rings. Named S/2004 1R the ring material is located just beyond the outer limit of the A-ring. Intersestingly this new ring is embedding the orbit of the moon Atlas. The new ring is seen left on the accompanying picture as the orbit of Atlas is shown red, right. The newly discovered ring is located 86,000 miles (138,000 km) from Saturn and it is about 190 miles (300 km) wide. It is badly known whether is extends or not all the way around Saturn. picture © site 'Amateur Astronomy', based on pictures NASA/JPL/Space Science Institute
New Mid-Sized Particles -or "Moonlets" Found in Saturn's Rings!
Cassini found that larger boulders -about small moons in fact- are orbiting inside Saturn's rings. Hence the rings are likely composed mostly of particles ranging in size from a half inch (1 cm) to the size of a small house, of those newly found objects -which counts by millions- with a size of about 300-ft (100-m) wide, and -to be complete- of two large-sized real moons -the 19-mile (30-km) Pan and the newly found 4-mile (7-km) Daphnis (the former S/2005 S1 orbiting inside the Keeler Gap as Pan inside the Encke Gap. Daphnis moves in and out of the ring-plane, and closer to and farther from the rings' edges as it orbits making the waves it makes change over time). The evidence for that class of objects inside Saturn's rings was found due to the disturbance they yield among the remaining particles. All this points to the idea that the rings likely have their origin into a shattered large object. The population described like just above surely reflects this origin with small particles, middle-sized ones and both large moons. The large moons only are able to clear a passage inside the rings as the middle-sized "moonlets" are just able to let a trace of their passage. The streak-looking disturbances seen on the attached picture are about 3-mile (5-km) long
4 More Rings Found. Likely Associated With Moons To Found! As an Inclined Feature In the D-Ring Points To a Collision, Or a Shattered Moon
As Saturn's ring could be imaged against the glare of the Sun, Cassini found a faint ring at the orbits of Janus and Epimetheus. A second ring was found overlying the orbit of the tiny Pallene (a tiny Moon found back in 2004) as a third and fourth ring were found in the Cassini Division. Astronomers are now to look for the moons -or shattered moons, or clumps of boulder-size rubble- which they think are at the origin of such rings. Such a disturbing moonlet might exist at, or near, the F-ring too. A wavy, spiral pattern observed in the outer part of the D-ring, on the other hand, could be traced back to a collision with a comet or meteoroid -with the ring itself, or with a moonlet there- in 1984. The picture, left, is a comprehensive view of the ring system as seen against the Sun. picture NASA/JPL/Space Science Institute
Most Important Finding by Cassini as Particles in the Rings Grouped Into Clumps!
Studies of the ring by Cassini using occultations of stars, are showing that, instead of uniformly dispatched particles -like thought before- those particles of the rings are actually grouped into clumps. Such a phenomenon matches exactly what occurs in a proto-planetary disk, with rocks and dust agglomerating into clumps and, eventually planets. Should the rings be farther from Saturn, such clumps of their particles would lead to the creation of new Saturn's moons. The proximity to the planet however makes that the clumps are constantly forming and tearing apart, once reaching 100 to 160 ft (30-50 meters) across. Clumps in the B-ring are broad and very flat, with smaller spaces between them than those in the A-ring. Particles in the clumps, in the B-ring, spend most of their time in almost continuous contact with other particles
Propeller-like Features Seen in a Zone of the A-Ring (Nov. 2007)
A 1,860-mile (3,000-km) wide zone of the A-ring is featuring propeller-like gravitational features, each side of small moonlets which yield them. Those features are 10 to 20 miles (16 to 32 km) across as it might sports about thousands of such moonlets with a size from semi-trailers to football stadiums. The narrowness of the region hints to that those boulders likely originate into a larger, 20-mile (32-km) wide moon shattered by a meteoroid or a comet. The discovery well bodes with the 'collisional cascade' theory about how the rings of Saturn were created: it seems like the breakup of a large moon happened hundreds of millions or even billions of yeaers ago, first created the rings, as further, smaller collisions and shatterings inside those, further complicated the rings structure
Particles Grouped at the Finest Level in the Rings (Feb. 2008)
Some unexplained process is further adding to the regularity of the rings' particles at Saturn, with regular resonances found into densely packed areas of the B or the innermost part of the A ring. Particles in the ring may collide and, their velocity modified, they are bunched together into those areas, with differences in velocity between the dense areas not impacting the relative position of them. Such areas are spaced by some 320-820 ft (100-250 meters) only
A Moonlet In the G-Ring Brings to Think that Saturn's Faint Rings are Due to Such Diminutive Moons Inside Them! (Mar. 2009)
A new moonlet has been discovered in the G ring and likely the main source of particles for it. The diminutive moon is only one-third of a mile (½-km) wide. The discovery allows to state that, in the Saturnian world, three rings, outside the main ones, are linked to a moonlet embedded in those and providing for the particles there. The scientists previously had found, into the faint G ring, a relatively bright and narrow arc of icy particles, extending 90,000 miles (150,000 km) or one-sixth of the ring and about 150 miles (250 km) in width. The orbit of that new moon, further, is interacted with by the nearby, larger Mimas, which is tought too to keep that ring arc together. Like in the other faint rings with a moonlet providing for the particles, there might be some more moonlets orbiting inside the G ring, with dimensions ranging for about a few, to several hundred feet (1 meter to some 120 meters). The particles in such faint Saturn's rings are likely due to collisions between meteoroids and the moonlets and smaller still objects, and between those objects between them
 | a view of three positions of the new moonlet discovered in the G-ring. picture courtesy NASA/JPL/Space Science Institute |
The Rings Seen Taller, by Places, Than Thought! (Sep. 2009)
Ripples as tall as the Rocky Mountains were found by Cassini in the rings are showing that those are not so thin than usually thought. They can be miles thick atsome points, with clouds kicked up by space debris impacting at the ring's particles, or by the gravitational tugs from some Saturn's moons! The rings, on the other hand, were found to reach a mere 30 feet (10 meters) by some locations. The discovery occurred during August 2009, with 2009 the year when the rings are seen edge-on, solar system-wide, a rare occurrence, allowing for Cassini to spot the shadows casted by the features. Another allowance of the occurrence also had Cassini observe that some unknown phenomenon event apparently tilted a vast region of the inner
rings relative to Saturn's gravitational field in a relatively short period of
time during the early 1980s. In the intervening years, the natural tendency of such inclined orbits has created a corrugation in the ring plane, extending
from the D across the C ring, right up to the inner B ring edge for a total
breath of about 11,000 miles (17,000 kilometers). Objects have been seen striking, by interval, the rings, creating small clouds of particles
Equinoxial Changes at The Ring System! (November 2009) The ring system is generally about 30 feet (9 meters) thick. Each Saturn's day, the rings are enduring a night which lasts between 6 and 14 hours. At the moment of the Saturn equinoxe, occurring one each 15 years, the rings are darkened during a whole four days, and reaching its lower temperature of minus 382 degrees Fahrenheit (minus 230 Celsius), like Cassini found in November 2009. The only, diminutive energy the rings are receiving at that time is coming from Saturn only. Cassini found too that the A-ring had not cooled as much as the remaining of the ring as that might be due to waves triggered by the shepherding moons and thus keeping exposing at their tops, by interval, the particles of the A ring to the light of the Sun
The Propellers Features Better Explained (June 2010) A new class of moonlets in the rings of Saturn
are creating distinctive propeller-shaped gaps in ring material located in the 'propeller belts', in the middle of Saturn's outermost A ring. Those objects, smaller than known moons, but larger than the particles in the rings. Numbering in the millions, they are not large enough however to clear out their
entire path like such moons like Pan and Daphnis. In another part of the A ring farther out from Saturn larger objects are to be found too, with propellers as much as hundreds of times as large, up to several thousand miles (kilometers) long and several miles (kilometers) wide. The moons embedded in the ring appear to kick
up ring material as high as 1,600 ft (0.5 kilometers) above and below the ring plane, which is well beyond the typical ring thickness of about 30 ft (10 meters). Those larger moonlets are though to be about half a mile (1 km) in diameter and number in the the dozens. Their orbits are seen shifting like due to gravitational considerations. Gravitational disturbances from Prometheus, on the other hand, are triggering the formation of objects as large as 12 miles (20 km) in diameter in the F ring. Such snowballs likely have lifetimes of only a few months. The 3 to 6 miles (5-10 km) in diameter object that Cassini scientists spotted in 2004 and dubbed S/2004 S 6 might be one of those as it occasionally bumps into the F ring and produces jets of debris. Propellers and other features called 'straws,' generally, are caused by clumping ring particles and small, embedded moonlets, respectively. Propellers are one feature created by small moonlets embedded in the rings as they attempt, unsuccessfully, to open gaps in the ring material. Some consider propellers analogous to baby planets forming in disks around young stars
The Mimas-Related Instability Region In the B-Ring at Last Explained! (November 2010) The outer
portion of Saturn's B ring is one of the most dynamic regions in Saturn's rings. As astronomers until now thought that the region mostly was controled by the gravitational perturbations of Mimas albeit with a ring's behavior far more complex than anything Mimas alone might do, they recently found, by 2010, that that region likely is the site of ring-embedded moonlets which might have migrated across the outer part of the B ring in the past and got trapped in a zone affected by the moon Mimas' gravity. The motion of those 1,000-ft (300-m) moons are creating vertically compressed-formed structures as tall as 2.2 miles (5 km). The Cassini mission already had discovered a moonlet embedded there. Studies linked to Saturn rings, scientitsts say, are also applicable to other celestial disks of a far grander scale, from solar systems, like our own, all the way to the giant spiral galaxies. Mostly the 'natural', large-scale wave oscillation frequencies inside a rotating disk might also be found too about other disk systems, like spiral disk galaxies and proto-planetary disks found around nearby
stars. At Saturn, such waves are occurring due to a process called 'viscous overstability' by which ring particles' small, random motions feed energy into a wave and cause it to
grow up to chaotic waveforms from tens of meters up to hundreds of kilometers wide in the Saturnian ring example. Normally viscosity, or resistance to flow, damps waves as in that case viscosity, in the densest parts of the ring, actually amplifies waves
The Corrugated Pattern in The Rings Explained! (March 2011)
Alternating light and dark bands, extending a great distance across Saturn's D
and C rings have been spotted by 2006 in the Saturnian rings looking like the
corrugations of a tin roof. Equinox images revealed the true dimension of this corrugation, extending
completely across the C ring, right up to the inner B ring edge for a total
breath of about 12,000 miles (19,000 km). Astronomers are now confident that that was due to a some few kilometer-wide object, a cloud of comet debris likely- which plunged into the inner rings by the second half of 1983. Saturn's gravity on the area then warped the orbits of some particules into a tightening spiral. It's by unwinding the spiral that scientists were able to find the date at which the effect began back. A same phenomenon also is affecting the faint rings of Jupiter as the main ripple-producing culprit there was comet Shoemaker-Levy
9 in July 1994. More collisions that thought occurs into the rings of the gas giants than though, a few times per
decade for Jupiter and a few times per century for Saturn. When meteoroids, generally, break up on a first encounter with the rings, they create smaller, slower pieces that then enter into orbit around Saturn. The impact into the rings of these secondary meteoroid bits kicks up clouds which soon are pulled into diagonal, extended bright streaks. The meteoroids at Saturn are estimated to range from about one-half inch to several yards (1 centimeter to several meters) in size. Vertical corrugation can be produced from an initially inclined ring by the natural tendency for inclined orbits to wobble systematically and slowly at different rates, depending on their distance from Saturn
Methone, Pallene and Anthe (June 2012)
Cassini discovered Methone and two other small moons, Pallene and Anthe, between
the orbits of Mimas and Enceladus between 2004 and 2007. The three tiny moons,
called the Alkyonides group, are embedded in Saturn's E ring, and their surfaces
are sprayed by ice particles originating from the jets of water ice, water vapor
and organic compounds emanating from the south polar area of Enceladus
->A Serene, Majestic and Accurate View of the Rings!
 | Another, majestic and most accurate view of the Saturn's rings! The density of the B ring is greater than that of the A or C rings. The Encke Gap holds inside three ringlets with a dynamical structure each as such transient clumps are in part due to the gravitational effects of Pan. The view is in natural colors. This view likely will become a handbook one!. picture courtesy NASA/JPL/Space Science Institute |
 | A view of the rings under equinox illumination in August 2009 allows for more details (in black-and-white only). more details in the text below. picture courtesy NASA/JPL/Space Science Institute |
 | The entire ring is viewed in natural color. The ring is seen from beneath at a 4° angle. It spans from 46,333 to 84,991 miles from the planet's center (74,565 kilometers to 136,780 km). Gaps, gravitational resonances and wave patterns are all present. Variations in color are due to meteoritic dust contamination as variations in brightness are to varying particle sizes and concentrations. Image taken Dec. 12, 2004, 1.1 million miles away (1.8 million km). picture courtesy NASA/JPL/Space Science Institute |
 | The ring is seen at a low angle. The moon at the forefront is Prometheus. View in visible light. picture courtesy NASA/JPL/Space Science Institute |
 | The ring is seen here on its side opposed to from where the sunlight is coming, with the brightest parts being where the rings allow the scattered sunlight to pass through. The outer part of the B ring, generally, is often exhibiting an irregular, patchy appearance, when seen in a proximity. picture courtesy NASA/JPL/Space Science Institute |
  | F-ring seen from afar during Saturn Orbit Insertion, Jul 2004 (1). F ring seen after first Titan flyby, Oct 2004 (2). The F ring resolved into five separate strands, or ringlets, with a bright central core. The core is 31 miles (50 km) wide. A third view adds to the understanding of the F-ring. Cassini allowed to see the F-ring like a flock of icy ring particles shepherded by Prometheus and Pandora. pictures courtesy NASA/JPL/Space Science Institute |
 | |
 | An edge-on view of the F ring against a moon is showing its near (up) and far (bottom) edges. The dark strip in-between is likely the A and B rings' material. It has been noticed during the 1995 Saturn ringplane crossing that the brightness of the rings when viewed nearly edge-on was dominated by the F ring. picture courtesy NASA/JPL/Space Science Institute |
 | It seems that the F ring's appearance is varying depending on how recently and how close both sheperding moons to the ring -Prometheus or Pandora- perturbed the ring. Here are shown 4 sections of the ring which are showing different features although imaged within a few hours. Such gravitational disturbances produced by moons on the F-ring might lead to a basic structure of it, that one shearing then, due to that the inner part of the F-ring core is orbiting Saturn faster than the outer part. picture courtesy NASA/JPL/Space Science Institute |
 | A further view of the kinks and gores produced into the F-ring by the passages of Prometheus. The image has been expanded in the horizontal direction by a factor of five to make details more prominent. The F ring was discovered by NASA's Pioneer 11 spacecraft in 1979. Prometheus and Pandora, the small "shepherding" moons on either side of the F ring, were discovered a year later by NASA's Voyager 1. The F ring resides at a balancing point between the tidal force of Saturn trying to break objects apart and self-gravity pulling objects together. The F ring might be only a million years old, but gets replenished every few million years by moonlets drifting outward from the main rings. picture courtesy NASA/JPL/Space Science Institute |
 | A other view of 'gores' at the F ring, to the left of the bright clump, and a 'jet,' to the right of the bright spot. Thanks to the ring's interaction with the moons Prometheus and Pandora, and perhaps a host of smaller moonlets hidden in its core, the F ring is a constantly changing structure, with features that form, fade and re-appear on timescales of hours to days. picture courtesy NASA/JPL-Caltech/Space Science Institute |
 | Numerous small satellites, or moonlets, added to Prometheus and Pandora, are linked to the F-ring as they are causing disturbances inside it. The disturbance seen here is likely due to a small population of moonlets of miscellaneous sized which are colliding with the ring's core. A part of such moonlets is seen left!. picture courtesy NASA/JPL/Space Science Institute |
 | Solid objects embedded into dusty structures inside the F ring hint to that they survive several collisions with the latter. The faint retinue of dust around them is likely the result of a most recent collision. The core of such objects might result from perturbations triggered by Saturn's moon Prometheus. picture site Amateur Astronomy based upon a picture courtesy NASA/JPL-Caltech/Space Science Institute |
 | Pandora is seen here contemplating the F ring, as some parts of the later are less perturbed than its core. picture courtesy NASA/JPL/Space Science Institute |
 | Another view of the F-ring core. Pandora is seen (bottom) faintly illuminated by "Saturnshine". Saturn’s F-ring is hosting a variety of dynamic features including channels, ripples and 'snowballs' that are created by the gravitational influence of nearby moon Prometheus. Small surviving fragments of such snowballs -which otherwise usually are destroyed by collisions- punch through parts of the F-ring, dragging icy ring particles with them and leaving glittering trails behind them, or 'mini-jets' of typically 20 to 110 miles (40 to 180 kilometers) in length. Mini-jets are thought to be caused by low-speed collisions in the core of the F ring ejecting dusty material from the core. That shows how the F ring is even more dynamic than astronomers thought, a bustling zoo of objects from a half mile [kilometer] in size to moons like Prometheus. In some cases, the objects traveled in packs, creating mini-jets that looked quite exotic, like the barb of a harpoon. picture courtesy NASA/JPL/Space Science Institute |
 | The F-ring seen edge-on reveals two puzzling features: a bulge (top) and a dark lane (bottom). The bulge might be very faint material or the evidence for an embedded object stirring the region (or the surface of which, covered by debris due to an impact, providing the dust). The Voyager missions had seen more of these clumps. The lane is still not understood. picture courtesy NASA/JPL/Space Science Institute |
 | A faint strand is seen left of the F-ring, as such strands has been seen by Cassini to curl around the planet in a tight, rotating spiral. The spiral structure might be due to disturbance of micron-sized particles in the F-ring by a tiny moon or moons. While the overall number of clumps in the F ring compared to when seen by the Voyager mission 30 years ago, remained the same, the number of exceptionally bright clumps of material plummeted during that time. While a variety of features in Saturn's many rings display marked changes over multiple years, the F ring seems to change on a scale of days, and even hours. Astronomers hypothesize that the brightest clumps in the F ring are caused by repeated impacts into its core by small moonlets up to about 3-mile (5-kilometer) wide, whose paths around Saturn lie close to the ring and cross into it every orbit. The F ring encircles the planet at a special location, near a place called the Roche limit, under which tidal forces from the planet's gravity tear apart smaller bodies. Material at this distance from Saturn can't decide whether it wants to remain as a ring or coalesce to form a moon. Prometheus further orbits just inside the F ring, stirring up the ring particles, sometimes leading to the creation of moonlets, and sometimes leading to their destruction.Every 17 years, the orbit of Prometheus aligns with the orbit of the F ring in such a way that its influence is particularly strong. One thinks this periodic alignment might spur the creation of many new moonlets. The moonlets would then crash repeatedly through the F ring. Fewer clumps would be created as time goes by, because the moonlets themselves are eventually destroyed by all the crashes. picture courtesy NASA/JPL/Space Science Institute |
 | Small objects likely are embedded in the F ring as they are interacting with material in the core of the ring, such interactions yielding jets. Those objects however are difficult to spot at the resolution available to NASA's Cassini spacecraft as their handiwork only reveals their presence. picture courtesy NASA |
 | The one main core of the F-ring is well seen here along with its 3 ringlets as 3 ringlets are seen too inside the Encke gap. Some sections of the ring have been seen having two bright strands instead of one. picture courtesy NASA/JPL/Space Science Institute |
 | The tenuous G ring, which is located beyond the F ring, is seen here due to a 3½-minute exposure by Cassini. The trail in the upper right is another star trail. picture courtesy NASA/JPL/Space Science Institute |
 | The G ring is made of fine, dust-sized icy particles and features a diffuse outer boundary as the inner edge is sharp. Studies in the summer of 2007 have shown that Saturn's G ring likely is the result of micrometeoroids colliding with relatively large, icy particles which are amazingly located within an arc of the ring only, due to the gravitational influence of Mimas. The particles released by the collisions are then swept along the ring by Saturn's magnetic field's plasma. picture courtesy NASA/JPL/Space Science Institute |
 | This picture is finely illustrating how icy material spewing from Enceladus is injecting into the E-ring, contributing to its formation. picture courtesy NASA/JPL/Space Science Institute |
 | The entire ring seen Oct. 29, 2004 from 519,000 miles (836,000 km) away. View is in the infrared. Differences in brightness are revealing differences in concentration of particles. picture courtesy NASA/JPL/Space Science Institute |
 | Seen on Oct 27, 2004 from 392,000 miles (631,000 km) away the ring is seen here lit from below. This yields that the thicker the part of the ring, the darker. Picture taken in violet light only. Parts of the rings are tenuous and made up of dust particles that tend to scatter light in roughly the original direction it was traveling, or 'forward scattering.' That makes them to glow brigthly when illuminated backwards by the Sun. picture courtesy NASA/JPL/Space Science Institute |
 | The inner part of the ring is seen here lit from below. Note Saturn's globe left. View in the infrared. Depending on how the beginning of the D-ring is seen, it may look like a meager, isolated ring, independent from the rest of the D-ring structure. picture courtesy NASA/JPL/Space Science Institute |
 | Detailed view of the C ring. The area extends 46,600 miles (75,000 km) from Saturn. The dark gap near the center is the Colombo gap along the Colombo ringlet. The ringlet is in resonance with Titan. picture courtesy NASA/JPL/Space Science Institute |
 | Detailed view of the outer part of the C ring with the Maxwell gap which contains the eccentric Maxwell ringlet, a Saturnian analog of the narrow Uranian epsilon ring. The gap also includes another very faint ringlet newly discovered. View in the visible. picture courtesy NASA/JPL/Space Science Institute |
 | Detailed view of the B ring. The gradation from darker to bright is due to differences in composition and ring particle density. View in the infrared. picture courtesy NASA/JPL/Space Science Institute |
 | the B ring (behind the overexposed Moon Rhea) is seen here lit from below. White zones are where the light is passing through more easily. View in the visible. picture site 'Amateur Astronomy' based on a picture NASA/JPL/Space Science Institute |
 | Mid-B ring structure (seen here in the infrared) have still to be understood. picture NASA/JPL/Space Science Institute |
 | Most detailed view ever of the ring (B and A rings). Dot right is noise. picture courtesy NASA/JPL/Space Science Institute |
 | See the Huygens Gap within the Cassini Division, bottom left of the picture. Image taken in visible green light. picture courtesy NASA/JPL/Space Science Institute |
 | The outer part of the B ring is seen in details here along with the Cassini Division. The sharp edge of the B ring is due to the influence of the moon Mimas. The Cassini Division is interestingly seen filled with plateau-like bands. The darker region between both is the Huygens Gap, with the Huygens ringlet. The view is in the visible light. picture courtesy NASA/JPL/Space Science Institute |
 | A grainy texture has been found by Cassini in 2006 at the outer edge of the B ring. View in the visible. picture courtesy NASA/JPL/Space Science Institute |
 | Another detailed view -in color, as seen from above, of the Cassini Division. The sharp end of the B-ring is maintained by a strong resonance with the moon Mimas. For every two orbits made by particles at this distance from Saturn, Mimas makes one orbit. The moon's repeated gravitational tugs force ring particles away from this region. picture courtesy NASA/JPL/Space Science Institute |
 | A fine view of the material strips existing inside the Cassini Division (right). The Moons is Enceladus, lying there on the near side of the ring. picture courtesy NASA/JPL/Space Science Institute |
 | This false-color ultraviolet is showing how the B (center) and A ring (right) were seen as Saturn was occulting the star 26 Taurus. This study has shown that there are more particles near the inner edge of the A-ring. picture courtesy NASA/JPL/University of Colorado |
 | New structures discovered inside the Encke gap. picture courtesy NASA/JPL modified site 'Amateur Astronomy' |
 | Most detailed view ever of ring particles (at A-ring). Particles are well seen. Horizontal lines are noise and will disappear once the picture processed. picture courtesy NASA/JPL/Space Science Institute |
 | Equinox light allowed for that view of vertical structures rising abruptly from the outer edge of the B ring to cast long shadows. The section of ring is 750-mile (1,200-km) long as structures are towering as high as 1.6 miles (2.5 km) above the plane, a significant deviation from the vertical thickness of the main A, B and C rings, which is generally only about 30 ft (10 m). The cause might be that the region is where large bodies, or moonlets, up to a kilometer or more in size, are found, these bodies significantly affecting the ring material streaming past them and forcing particles upward. picture courtesy NASA/JPL/SSI |
 | General view of rings features. In the infrared the thicker the ring, the less bright. Water ice is seen in greater quantity in the A-ring. "Dirt" is seen at rings thinner parts like the Cassini and Encke divisions as in other small gaps. picture courtesyNASA/JPL/University of Arizona |
 | The F ring is seen right, as the outer part of the A ring is seen near center, and the dark zone left is the Encke Gap. It's the fine, icy material contained in the F ring and the two ringlets of the Encke Gap which make the ring particularly bright and the ringlets particularly visible. Pandora (right) and Prometheus (left) are seen too. picture courtesy NASA/JPL/Space Science Institute |
 | A ring with the Cassini Division (left) and the Encke gap (right) seen in the ultraviolet. Ultraviolet is showing is showing how the rings go from "dirty" and smaller particles (red) to cleaner and larger ice particles (turquoise) with the distance to Saturn. picture courtesy NASA/JPL/University of Colorado |
 | Using a star occultation, Cassini spotted where the shepherding moons Janus and Pandora are making the ring denser. The brighter zone left is the zone of influence of Janus, the smaller zone right is of Pandora. The picture is 450-mile wide (724 km) only. picture courtesy NASA/JPL/University of Colorado at Boulder |
 | The A ring (bottom) is seen at the foreground of the ring's projected shadows on Saturn's disc. The moon, top right, is Mimas. Image taken at 2.3 million miles (3.7 million km) from Saturn. picture courtesy NASA/JPL/Space Science Institute |
 | These three images, originally part of a same view of the ring (in visible light) are showing that the Cassini Division, although dark is much more filled with material that its apparent look, idem for the Encke Gap and that the F ring is flanked either side by two faint ringlets. picture courtesy NASA/JPL/Space Science Institute |
 | A close-up view of the inner A ring is showing variations inbrightness along the direction of ring motion -- from top to bottom. Such dark regions appear to widen and then narrow, and thin bright regions disappear altogether. Such variations might be smoothed out quickly by ring particle motion. Is such a phenomenon to be linked to the spoke phenomenon?. picture courtesy NASA/JPL/Space Science Institute |
 | Spokes are transitory features which the Voyager missions observed for the first time. Astronomers think that spokes are radial as they appear, as their origin is still ill-known, albeit the observations by Cassini hint to that the spokes are likely due to both Saturn's gravity and magnetic field. 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. picture courtesy NASA/JPL |
 | These are the sharpest images taken of a propeller so far, and show a unprecedented level of detail. The propeller's central moonlet would only be a couple of pixels across in these images, and may not actually be resolved here. A bright, narrow band of material connects the moonlet directly to the ring, in agreement with dynamical models. Lengthwise along the propeller is a gap in the ring that the moonlet has pried open. Wavy edges are clearly visible in the gap emphasizing that the gap must be sharp-edged. The gap has a width of 1.2 miles (2 kilometers), revealing the mass of the central moonlet at that of a snowball about 0.6-mile (1-kilometer) wide. picture based upon a picture courtesy NASA/JPL-Caltech/Space Science Institute |
 | The equinox at Saturn allowed Cassini to spot objects in the ring projecting shadows. Scientists believed that one might be a moonlet as it might protrude by 500 feet (150 meters) above the ring plan. picture based upon a picture courtesy NASA/JPL/Space Science Institute |
 | A wave structure is seen in a part of Saturn's B ring known as the 'Janus 2:1 spiral density wave,' by some 59,800 miles (96,233 kilometers) from the planet. That density wave originates from that ring particles there orbit Saturn twice for every time the moon Janus orbits once, creating an orbital resonance. As Janus is trading its orbits with Epimetheus every four years, that yields a new crest in the structure and the distance thus between any pair of crests corresponds to four years’ worth of the wave. Epimetheus also generates waves but they are swamped by the ones from Janus, which is a larger moon. Density waves also are extant in Saturn's A ring. picture based upon a picture courtesy NASA/JPL-Caltech/Space Science Institute |
 | That composite of a 'true' and 'enhanced' color image constitutes the highest-resolution image of a portion of the inner-central part of Saturn's B Ring, at between 61,300 and 65,600 miles (98,600 and 105,500 kilometers) from the planet's center. The view was taken by July 2017 during Cassini's last phase of its mission to the ringed planet. A still unknown material (upper part) is bestowing a tan color on the rings -- which are mostly water ice and would otherwise appear white. The view below is showing in blue areas less reddish in true colors as in red areas redder. picture based upon a picture courtesy NASA/JPL-Caltech/Space Science Institute |
Shepherding moons are mostly linked to such or such part of the ring, or ring, of Saturn. They are thought to have a gravitational importance to the particles there. Gravitational waves of the small moons in and about the ring are triggering the formation of objects as large as 12 miles (20 km) in diameter with a life of a few months, like in the F-ring for example. The F-ring on the other hand may be only a million years old, but gets replenished every few million years by moonlets drifting outward from the main rings. Such data are considered a help for a better understanding of how protoplanets and planets are forming inside a protoplanetary disk surrounding a star. From the narrow F ring, to the gaps in the A ring, to the Cassini Division, Saturn's rings are a masterpiece of gravitational sculpting by the small, inner moons of the ringed planet. Pandora and Prometheus, for example, help confine the F ring and keep it from spreading. Pan and moons like it have profound effects on Saturn's rings, ranging from clearing gaps, to creating new ringlets, or raising vertical waves that rise above and below the ring plane. Many of them also create waves at distant points in Saturn's rings where ring particles and moons have orbital resonances. Pan, for example, maintains the Encke Gap in which it orbits, but it also helps create and shape the narrow ringlets that appear in it. Five tiny moons nestled in and near Saturn's rings are covered with material from the planet's rings (for the two closest of them to Saturn like Daphnis and Pan) or, for the farthest away of them (Atlas, Prometheus and Pandora) from icy particles blasting out of Saturn's larger Enceladus. Those moon surfaces are also be highly porous, confirming that they were formed in multiple stages as ring material settled onto denser cores that might be remnants of a larger object that broke apart. The porosity also helps explain their shape: rather than being spherical, they are blobby and ravioli-like, with material stuck around their equators. That might hint to such a behavior also occurring at each particle in the rings. Ring moons closest to Saturn appear the reddest, similar to the color of the main rings which might be due to a mix of organics and iron as the farthest ones appear more blue, similar to the light from Enceladus' icy plumes
->Moons' Hunt!
A New Moon at the F-Ring?
A new moon might have been found at the exterior of the F-ring at about 620 miles (1,000 km) from the ring. The object, which has been named S/2004 S3, is estimated to be 2-3 miles (4-5 km) wide as it is orbiting at about 86,420 miles (141,000 km) from Saturn. The object is seen inside the green box on the accompanying picture. S/2004 S3 orbit is lying within 190 miles (300 km) of the orbit of the moon Pandora. It might be just a clump in the ring as well. On the other hand, a further view of the object has shown that it seemed to have turned to the interior of the F-ring. Such an orbit, crossing the ring, would be a dynamical puzzle. Hence this second location of S/2004 S3 has been considered a second, independent, object and named S/2004 S4 picture courtesy NASA/JPL/Space Science Institute
Two New Small Inner Moons Seen at Saturn!
Two small inner moons have been found orbiting at Saturn between Mimas and Enceladus. Provisionally named S/2004 S1 and S/2004 S2 the moons are 2 and 2.5 mi wide (3 and 4 km), and are orbiting 120,000 and 131,000 miles from Saturn (194,000 and 211,000 km) respectively. S/2004 S1 might be S/1981 S14 once spotted on a single image by one of the Voyagers. Smallest moons until now were 12 miles (20 km). The search for undiscovered moons is one of Cassini missions. Such moons were expected to be found inside the gaps of the ring or near the F-ring. This discovery is of importance as such bodies should have been shattered by small comets long ago. The discovery puts a constraint on how much such comets existed in the outer solar system at the origins, hence it helps to better understand the Kuiper Belt objects and the cratering histories of moons around the gas giants. On the other hand such a finding might have been expected as, if any of the small inner moons of Saturn woud have been smashed to debris by comets, they would have formed a ring and then built back to a moon. Hence such new moons might be found again! One of the new moons seems to have endured a drift since its formation, like most moons of the outer solar system, due to tidal force; its orbit eccentricity and inclination might have been changed along the drift. The search is still on too for new moons in the ring gaps! Moons were discovered as of June, 1st 2004 as Cassini was 10.3 million miles (16.5 million km) from Saturn, still approaching the planet. Such findings are made using a dedidacted imaging sequence. S/2004 S1 is left in the picture, as S/2004 S2 is right; both are box-framed
Those moons seem to have been named Methone and Anthe, as partial, near-invisible arc rings seem to exist along the orbits of Methone and Anthe, both moons being likely at the origin of the faint rings, in a process similar to what is seen at Jupiter with Amalthea, Thebe, Metis and Adrastea. Such phenomenon too exist at the orbits of Janus, Epimetheus and Pallene. Methone, Pallene and Anthe, called the Alkyonides group, are embedded in Saturn's E ring, and their surfaces
are sprayed by ice particles originating from the jets of water ice, water vapor
and organic compounds emanating from the south polar area of Enceladus
picture courtesy NASA/JPL/Space Science Institute
A Moon in the Keeler Gap!
As it's studying the ring, Cassini discovered a new moon last May 1, 2005, inside the Keeler Gap, this narrow gap just before the boundary of the A-ring. The moon has been provisionally named S/2005 S1 and has been seen to generate wavy pattern on both sides of the gap. These patterns are moving along the edges at the same pace than the moon. S/2005 S1 is 4-mile wide (7 km) and it has an important albedo, similar to the one of the particles of the ring. The orbit of the newly discovered object likely marches the exact center of the gap, about 84,820 mi (136,505 km) from the center of Saturn. The orbit's eccentricity is still unknown. S/2005 S1 becomes, after Pan (16-mile wide, 25 km), which orbits inside the Encke Gap, the second moon at Saturn to orbit inside a gap in the ring. It seems that the wavy patterns seen along a gap are a sure marker of the presence of a moonlet. Cassini scientists are expecting more moons from the other smaller gaps in the ring. The study of the interaction of such embedded moons with the ring is illuminating the studies about the formation of the solar systems from the protoplanetary disks. The new moon has been named Daphnis, as the Keeler Gap is a mere 26 miles (42 km) wide. pictures: site 'Amateur Astronomy' (left) based on pictures NASA/JPL/Space Science Institute; pictures have been taken from above the ring plane, NASA/JPL/Space Science Institute (right; enhanced by this site for the central part of the picture)
The 60th Moon of Saturn, a Moonlet, Found!
A new moonlet, S2007 S4, the 60th moon of Saturn, has been discovered by Cassini during the summer of 2007, a moon of about 1.2 miles (2 km) in diameter, mostly made of ice and rocks. Its orbit is located between the orbits of the moons Methone and Pallene. The moon's orbit is in resonance with another moon, Mimas, as, with Methone, Pallene it might form a part of a larger group of moons in the region
More About how the 14 Smallest Moons of Saturn Formed!
The 14 smallest moons of Saturn likely originated into seemingly large fragments of the primordial, shattered moons which formed the rings, with dust of the rings aggregating unto those, allowing for those little moons to grow despite of the defavourable gravitational environment there. The small moons of Saturn have a density the half of that of water ice. Some of those moons, like Pan or Daphnis cleared gaps into the rings, as some others, like Pan or Atlas, on the other hand, has got a flying saucer shape due to that they endured a secondary stage of accretion, bringing to some kind of accretion disks around those moons, as the Saturn's rings had attained their current thickness of 66 ft (20 m)
Two faint Moons likely Orbiting inside the F-Ring! Scientists found lately that two moons, one being S/2004 S6 and the other one a much small object, are likely orbiting inside the F-ring self, leading to further disturbances there
Resonances, Bright Lanes, Clumps
The inner, small moons of Saturn are shaping and maintaining the ring structure. The bright lanes, as well as the dark gaps (like the famed Cassini division) are due to the gravity of moons like Mimas, Janus or Prometheus nudging the ring's particles. Clumps in the F ring or in the ringlets inside the Encke Gap are due to gravitational interactions too with Prometheus and Pandora, and Pan, respectively. This view, as far as the main ring is concerned, is limited to the A ring. click the picture to a larger view. picture site 'Amateur Astronomy'
 | Prometheus successive radial influences. picture courtesy NASA/JPL/Space Science Institute |
->Partial, near-invisible arc rings seem to exist along the orbits of Janus, Epimetheus, and Pallene, the moons themselves likely at the origin of the faint rings, in a process similar to what is seen at Jupiter with Amalthea, Thebe, Metis and Adrastea. Such arcs are seen too at the orbits of two tiny Moons discovered between the orbits of Mimas and Enceladus
 | Seen here are the 6 of Saturn's minor moons which are orbiting just near the rings. Right are (from top to bottom): Epimetheus just outside F ring, Prometheus and tiny Atlas inside the ring, Pandora. Left is seen Janus. Rings and planet are overexposed. picture courtesy NASA/JPL/Space Science Institute |
 | Three ring-linked moons are seen here. Atlas (top center), Prometheus (bottom right), and Janus (bottom left). The bright line just beyond the Cassini Division is a density wave caused by Janus. Density waves caused by Atlas and Promotheus are to faint to see. picture courtesy NASA/JPL/Space Science Institute |
 | Seen here in visible green light, Atlas is seen silhouetted against Saturn and the ring. picture courtesy NASA/JPL/Space Science Institute |
 | These raw, unprocessed images of Saturn's moon, Atlas, were taken from a close-approach distance of about 7,000 miles (11,000 kilometers), the closest ever taken of Atlas. picture courtesy NASA |
 | Prometheus is seen here interacting with the F ring. A faint strand of material is seen as the ringlets of the F ring are disturbed in several ways (left), as the moon is attracting a strand of material (right). The streamers of material swept by Prometheus progressively become more elongated and increasingly aligned with the F ring, with time. Prometheus, the larger and closer to Saturn of the two moons shepherding the F ring, appears to be the primary source of the disturbances in ring. At its longest, the potato-shaped moon is 92 miles (148 km) (92 miles) across. It cruises around Saturn at a speed slightly greater than the speed of the much smaller F ring particles, but in an orbit that is just offset. As a result of its faster motion, Prometheus laps the F ring particles and stirs up particles in the same segment once in about every 68 days. When Prometheus enters the ring, it clears out some of the smaller ring particles. picture courtesy NASA/JPL/Space Science Institute |
 | Prometheus perturbing the F ring, creating dark streamer-channels. picture courtesy NASA/JPL/Space Science Institute |
 | Prometheus (left) and Pandora (right) the two F-ring shepherd moons. Top right is Janus. Due to density waves generated by their gravitational resonances, Prometheus and Pandora are generating 4 bright band either side of the 200-mi (325 km) wide Encke Gap. picture © site 'Amateur Astronomy' based on a picture courtesy NASA/JPL/Space Science Institute |
 | Prometheus as seen from 272,000 mi (438,000 km) on June 7, 2005. The moon's long axis points toward Saturn. picture courtesy NASA/JPL/Space Science Institute |
 | Another view of Prometheus. North is down. picture courtesy NASA/JPL-Caltech/Space Science Institute |
 | Stunning sci-fi view of Prometheus and the F-ring. The scar in the ring is what the moon let imprinted for some time each time it comes at its nearest to the ring. picture courtesy NASA/JPL/Space Science Institute |
 | Suggestive view of Prometheus and the F ring. picture courtesy NASA/JPL/Space Science Institute |
 | Pandora as viewed from 251,000 mi away (346,000 km). Like most of Saturn's ring moons, Pandora is likely an icy rubble pile, 52-mile (84-km) wide, loosely bound together by gravity. When such a moon has an elongated, oval-like shape, the long axis is oriented along the moon-Saturn line. picture courtesy NASA/JPL/Space Science Institute |
 | Closest views of Pandora. The craters on the surface seem covered back with a layer of debris. Grooves and ridges might be fractures affecting this overlying smooth material. The original picture is in false colors, as this one was translated into true colors by this site. picture courtesy NASA |
 | Pandora seen next to the thin line of the F ring. Pandora plays a smaller role than originally thought in shaping the narrow ring. Along with Prometheus, Pandora actually stirs the F ring into a chaotic state, generating a gap and streamer structure. Prometheus alone confines the bulk of the F ring as it establishes stable locations for F ring material where the moon's own gravitational resonances are least cluttered by the perturbing influence of Pandora. picture site Amateur Astronomy based upon a picture courtesy NASA/JPL-Caltech/Space Science Institute |
 | A fine view of Epimetheus. picture courtesy NASA/JPL/Space Science Institute |
 | Detailed view of Epimetheus, the co-orbital moon to Janus. Astronomers originally thought that Janus and Epithemeus were the same object as they realized that there are in fact two bodies sharing the same orbit and swapping positions approximately every 4 years. Epimetheus, like Phoebe, Iapetus, Hyperion, Dione and Saturn's F-ring likely sharing a common, comet-originating dark material. picture courtesy NASA/JPL/Space Science Institute |
 | Another view of Epimetheus as seen from 214,000 mi (345,000 km) away. picture courtesy NASA/JPL/Space Science Institute |
 | Most detailed view of Epimetheus. Many large, softened craters on Epimetheus point to a several billion years old surface. The crater below center is 21-mile (33 km) wide Hilairea. Epimetheus low density might point to a "rubble pile" composition. picture courtesy NASA/JPL/Space Science Institute |
 | Lumpy Epimetheus (70 miles -113 kilometers- across) is too small to have sufficient self-gravity to form itself into a round shape, and it has too little internal heat to sustain ongoing geological activity. North on Epimetheus is up and rotated 5 degrees to the left. picture courtesy NASA/JPL-Caltech/Space Science Institute |
 | That view of Epimetheus is one of the highest resolution ever taken. The view looks toward anti-Saturn side of Epimetheus and North is up and rotated 32 degrees to the right. picture courtesy NASA |
 | Janus and Epimetheus seen together in perspective. Janus is the nearest of both moons. Partial, near-invisible arc rings seem to exist at the moons' orbits, according to a process similar to the one which creates the faint rings of Jupiter. picture courtesy NASA/JPL/Space Science Institute |
 | 113-mile-wide Janus (181 km) seen from 684,000 miles (1.1 million km). picture courtesy NASA/JPL/Space Science Institute |
 | This close-up from Janus from 222,000 miles (357,000 km) is showing strange dark specks on the surface. Might it be that the underground at Janus be dark under a bright terrain? Like most of the gas giants' small moons, Janus is likely porous and water ice. Picture was taken on May 20, 2005. picture courtesy NASA/JPL/Space Science Institute |
 | This view is finely showing a general view of Janus. It was taken in the infrared. picture courtesy NASA/JPL/Space Science Institute |
 | A closer view of Janus. picture courtesy NASA/JPL/Space Science Institute |
 | Janus displays the usual irregular shapes of Saturn's smaller moons, hinting to mass inhomogeneities within. picture courtesy NASA |
 | Shadow-darkened parts of large craters of Janus in March 2012. picture courtesy NASA/JPL-Caltech/Space Science Institute |
 | Pan, the 7th Saturn's minor moon linked to the ring is seen here orbiting inside the Encke Gap. The Encke Gap is 200 miles (325 km) wide. picture courtesy NASA/JPL/Space Science Institute |
 | Two ringlets (top) are seen inside the Encke Gap where Pan is orbiting, with one just at the moon's orbit as gravitational wakes are seen (bottom) either side of the gap, due to interaction between the moon and the ring's particles. Ripples generated by Pan either side of the Encke Gap may be seen up to 4 months after the passage of the moon, as their spacing grow larger with the waves getting distant from the Gap. picture courtesy NASA/JPL/Space Science Institute |
 | Daphnis, this tiny moon that orbits inside the Keeler Gap is leaving waves along both sides of the gap! Pandora sculpts the F ring, as does nearby Prometheus as Daphnis meanwhile is busy holding open the Keeler gap. Ring particles experience tiny gravitational "kicks" from these moons and subsequently collide with other ring particles, losing orbital momentum. picture courtesy NASA/JPL/Space Science Institute |
 | Here is moon Daphnis which affects the Keeler Gap. picture courtesy NASA |
 | Wavemaker Daphnis is seen here within Keeler Gap as the gravity waves it raises are both the horizontal and vertical directions. picture courtesy NASA |
 | Atlas and Pan clearly seen with a flying saucer like shape!. picture courtesy NASA/JPL/Space Science Institute |
 | These raw, unprocessed images of Saturn's Pan, were taken on March 7, 2017 and the closest images ever taken of that moon. Cassini scientists think Pan formed in the rings of Saturn, with the ring material accreting on it and forming its main rounded shape at the time when the ring system was very young and vertically thicker. The distinctive, slender ridge around Pan's equator formed after the moon cleared the gap into which it he resides today and, at this point the ring has turned as thin as it is today. The material then kept raining down on or near the equator where the low gravity of Pan allowed to build up. picture courtesy NASA/JPL-Caltech/Space Science Institute |
With its last approach to Titan in a distant flyby on Sep. 11, 2017 at 5 p.m. EDT, Cassini was directed to its final plunge to Saturn. The probe then reached its last apoapse --the farthest from Saturn on its orbit-- at a distance of 800,000 miles (1.3 million kilometeres) before heading to the ringed planet. Cassini was back in contact with Earth on Sep. 12 as data were streamed down and, on Sep. 13, mission navigators confirmed that the mission was on its course to dive into the planet's atmosphere on Sep. 15 (a calculation predicted that loss of contact with Cassini should occur on Sep. 15 by 7:55 a.m. EDT). Imaging systems were scheduled to take a final image by 3:58 p.m. EDT on Sep. 14 with that image showing the location where the spacecraft was expected to enter Saturn's atmosphere and the location at that time on the planet's night side and lit by reflected light from the rings only. Always that same day, by 7:45 p.m. EDT, Cassini began transmitting data and final images, emptying its onboard solid-state recorder of all science data before reconfiguring for a near-real-time data relay during the final plunge. From that moment, communications link with the spacecraft get continuous through the mission's end 12 hours ahead. On Sep. 15, the day of the Cassini final plunge, by 4:55 a.m. EDT, the craft configured itself for the plunge and real-time relay of data, as the transfer of data signaled the beginning of the plunge, which began at 7:55 a.m. EDT and the loss of contact scheduled one minute later. NASA's Cassini spacecraft made its final approach to Saturn and dove into the planet’s atmosphere on Friday, Sept. 15 with loss of contact with the mission occurring on Sep. 15 by 7:55:46 a.m. EDT, with the signal received by NASA's Deep Space Network antenna complex in Canberra, Australia after a journey of 83 minutes (some ESA antennas on a other hand, had also help during the previous steps of the Grand Finale). The spacecraft entered the atmosphere on the planet's day side, near local noon, at 9.4 degrees north latitude, 53 degrees west longitude. Telemetry received during the plunge indicated that, as expected, Cassini entered Saturn's atmosphere with its thrusters firing to maintain stability, as it sent back a unique final set of science observations. Data from eight of Cassini's science instruments were beamed back to Earth. No images were to be taken during the final plunge into Saturn, as the data transmission rate required to send images was too high and would have prevented other high-value science data from being returned
 | A illustration of Cassini's path into Saturn's upper atmosphere, with tick marks every 10 seconds. Cassini's contact with Saturn's atmosphere occurred at a altitude of about 1,190 miles (1,915 kilometers) above the planet's estimated cloud tops --that altitude where the air pressure is 1 bar, equivalent to sea level on Earth-- at a speed of approximately 70,000 miles (113,000 kilometers) per hour. The predicted altitude for loss of signal was about 930 miles (1,500 kilometers) above cloud tops, whence the craft was to begin to burn up like a meteor, being destroyed within a couple of minutes (the craft, generally, in terms of what amateurs can see at Saturn, was destroyed before reaching the 'visible' layers of Saturn, above what is termed the 'well-mixed atmosphere'). picture based upon a picture courtesy NASA/JPL-Caltech |
 | This image, color adjusted by our site, of Saturn's northern hemisphere was taken by NASA's Cassini spacecraft on Sept. 13, 2017. It is among the last images Cassini sent back to Earth. The view was taken at a distance of 684,000 miles (1.1 million kilometers) from Saturn. picture based upon a picture courtesy NASA/JPL-Caltech/Space Science Institute |
 | Saturn's moon Enceladus is seen sinking behind the giant planet in a farewell portrait from NASA's Cassini spacecraft. The view is part of a movie sequence of images taken over a period of 40 minutes as the icy moon passed behind Saturn from the spacecraft's point of view. The images were taken at a distance of 810,000 million miles (1.3 million kilometers) from Enceladus and about 620,000 miles (1 million kilometers) from Saturn. picture based upon a picture courtesy NASA/JPL-Caltech/Space Science Institute |
 | That view is looking toward the planet's night side, lit by reflected light from the rings, and shows the location at which the spacecraft would enter the planet's atmosphere hours later. The view was taken at a distance of 394,000 miles (634,000 kilometers) from Saturn. picture based upon a picture courtesy NASA/JPL-Caltech/Space Science Institute |
