This natural color view showing Saturn, Titan and Tethys turns out to be one of the most fascinating images of the Saturn system in 2008. The image was generated with the Cassini probe wide-angle camera by combining images taken using red, green and blue spectral filters. The view was obtained on January 30, 2008 at a distance of about 1.3 million kilometers ( 800,000 miles ) from Saturn. The camera focuses on the unilluminated side of the rings from around 3 degrees above the ringplane. There is a "subtle shadow game" between Saturn and its rings: one can notice, notably, that Saturn's shadow darkens the far arm of the rings close to the planet's limb.
The orange moon, Titan, which moves around Saturn at a mean distance of 1,221,870 km ( roughly 763,669 miles ), appears on the upper right of the image, emerging from behind Saturn. The bright moon, Tethys, which orbits Saturn at a mean distance of 294,619 km ( around 184,137 miles ) appears in the lower left of the image below the rings of the Gas Giant.
This global view shows up the differences in appearance and size between the moons and the ringed planet: Saturn which is mainly composed of hydrogen and helium appears yellow whereas Tethys appears white and bright due to its high reflectivity and its high concentration of water ice. On the other hand, Titan appears orange because of its atmosphere, primarily composed of nitrogen, methane and other hydrocarbon molecules. Saturn is a giant body compared to Titan and Tethys: it is around 120,536 km in diameter ( around 75,000 miles ) whereas Titan is about 5,150 kilometers in diameter ( about 3,200 miles ) and Tethys is roughly 1,071 kilometers wide ( roughly 665 miles).

Image source: NASA, JPL

This ultraviolet view of Titan, released on December 31, 2008, was captured with the Cassini probe narrow-angle camera using a combination of spectral filters sensitive to wavelengths of polarized ultraviolet light centered at 338 nanometers. The image was taken at a distance of about 1.742 million kilometers ( 1.083 million miles ) from Titan and at a Sun-Titan-spacecraft, or phase, angle of 50 degrees.
The ultraviolet image allows us to discern stunning atmospheric characteristics of Titan's murky gas blanket: one can clearly notice, in this view, the north polar hood engulfing the "Arctic region" like a giant hurricane. It appears darker than the rest of the atmosphere. The second striking feature which draws our whole attention is the presence of a detached haze layer gliding over the deep, thick and opaque atmosphere. This haze layer appears globally distributed over the sphere.
Titan's atmosphere appears deeper and heavier than the atmospheres of the Earth, Mars or Triton. The atmospheric pressure at Titan's landing site was a little below 1.5 bars. Unlike planets or big moons like Mercury, Ganymede, Io or Europa, it paradoxically harbors a significant atmosphere which represents one of the key topics in planetary exploration.

Image source: NASA, JPL

This infrared view of Titan, centered on the Saturn-facing hemisphere, illuminates mainly the trailing hemisphere that is the hemisphere opposite to Saturn. The view was obtained with the Cassini probe narrow-angle camera on November 9, 2008 using a spectral filter sensitive to wavelengths of infrared light centered at 938 nanometers. The image was acquired at a distance of about 1.774 million kilometers or 1.102 million miles from Titan and at a Sun-Titan-spacecraft, or phase, angle of 56 degrees.
The illuminated area notably includes the region of Senkyo roughly in the middle of the illuminated part, appearing mostly dark in infrared images. Above it, the region of Aaru is also discernable. A portion of the dark regions of Fensal / Aztlan can also be identified to the west of the Senkyo region. The dark landscape features primarily appear in the equatorial region. Radar images show that dark regions are, to a large extent, dominated by dune fields, probably shaped by strong winds.

Image source: NASA, JPL

This set of radar images shows potential active cryovolcanic areas on Titan on the basis of brightness variations in VIMS images of the same locations. The left radar view was obtained on February 22, 2008 by the Cassini Radar Mapper and the radar image on the right was captured on April 30, 2006. Both radar images show regions which are situated in the bright Xanadu area. Region 1, surrounded by the white line, lies in the eastern part of Xanadu, just north of the feature named Hotei Arcus and is centered on 28 degrees south latitude by 78 degrees west longitude. The region is roughly 400 kilometers or 249 miles across. Region 2, also surrounded by a white line, is located on the western part of Xanadu and is centered on 7 degrees south latitude by 135 degrees west longitude. This area is roughly 900 kilometers or 560 miles across. In both radar images, north is up, and landscape characteristics as small as 300-500 meters can be resolved.
Scientists suspect that both regions undergo a cryovolcanic activity because infrared images have revealed changes in brightness in these regions. An apparent haze has also been observed gliding over flow-like surface formations, probably associated with cryovolcanic phenomena. The lobate, flow-like features in region 1 are likely to be linked to icy volcanism. In region 2, multiple topographic fractures or channels can be clearly spotted as well. Are they related to ethane or methane rain or are they linked to a subsurface activity engendering "crustal fracturing" and eruptions of methane ethane, ammonia or water? Some scientists suggest it is tempting to say that it is a Europa-like process.

Image source: NASA, JPL

This infrared projection map of Saturn's largest moon Titan was built on the basis of images obtained by the Visual and Infrared Mapping Spectrometer from the Cassini probe. It especially reveals two regions that changed in brightness, identified by a blue and yellow marking. The global view is an overlay of all the high-resolution images from the first 45 flybys, up through last February 2007 and the map was generated using the 2.1 micron wavelength. The image scale is roughly 25 kilometers ( 16 miles ) per pixel or 1.8 pixels per degree.
The two labeled regions, located between the Shangri-Là region and the Fensal / Aztlan region, in the Xanadu area, are hypothesized by some to be areas of cryovolcanic activity. The change in brightness is, indeed, potentially the sign of a volcanically active region. In the harsh environment of Titan, volcanoes might well be very exotic, expelling cryolava onto the surface of the moon. Actually, the material ejected by cryovolcanoes is probably made up of volatiles such as water, ammonia and methane instead of the terrestrial molten rock. Several radar or infrared data collected by the Cassini spacecraft during its Saturn tour suggest the existence of an active cryovolcanism on Titan. For instance, scientists have identified a suspect haze hovering over flow-like surface formations and they consider it is likely the result of icy volcanism.
The presence of a relatively high concentration of methane in Titan's atmosphere might well be the outcome of methane eruptions from cryovolcanoes which would bring a continuous supply of fresh methane into Titan's gas blanket. Some scientists think that without replenishment from Titan's cryovolcanoes, the original atmospheric methane should have been exhausted long ago.

Image source: NASA, JPL

This infrared image of Titan which unveils the orange moon on its Saturn-facing hemisphere was captured with the Cassini probe narrow-angle camera on October 11, 2008 using a spectral filter sensitive to wavelengths of infrared light centered at 938 nanometers. North is up. The view was acquired at a distance of about 2.222 million kilometers or 1.381 million miles from Titan and at a Sun-Titan-spacecraft, or phase, angle of 10 degrees.
The infrared views allow scientists to pierce through the deep and opaque atmosphere and identify landscape or topographic features such as mountains, volcanoes, craters, ice blankets or pools of liquid. The dark features tend to reveal a more absorbing material than the bright patches: this global view clearly shows the regions of Fensal, Aztlan and Quivira as well as the circular feature of Sinlap in the east part of Fensal. The regions of Aaru and Senkyo appear in the east of the dark regions Fensal and Aztlan and the bright region of Tsegihi lies below Aztlan.

Image source: NASA, JPL

This infrared view of Titan was obtained with the Cassini probe narrow-angle camera on September 30, 2008 using a spectral filter sensitive to wavelengths of infrared light centered at 938 nanometers. The image was acquired at a distance of about 1.2 million kilometers or 776,000 miles from Titan and at a Sun-Titan-spacecraft, or phase, angle of 71 degrees. The north of Titan is up and rotated 16 degrees to the right.
Some bright cloud streaks similar to Cirrus on Earth appear to encircle the northern latitudes of the Saturn moon. The same kinds of cloud bands have also been encountered in the southern hemisphere, generally at 40 degrees south latitudes, similar to Wellington, New Zealand. One can notice that those cloud formations in the northern hemisphere, appear farther from the equator, near 56 degrees north latitude, which corresponds to the same latitude as Glasgow, Scotland or Moscow, Russia. Those meteorological observations in Titan's atmosphere raise new questions for scientists: why such clouds appear, more often, at high latitudes ? And why are the northern cloud streaks identified at higher latitudes than the same kind of cloud streaks in the southern hemisphere ? Is it related to seasonal processes ? The radar images provide some clues: Titan's north polar region is covered with a myriad of lakes and seas, probably more than in the south polar region. As a result, the exchanges with the atmosphere via evaporation and precipitation are probably more developed in the north polar region.

Image source: NASA, JPL

This infrared view of Titan was obtained with the Cassini spacecraft narrow-angle camera on September 25, 2008 using a spectral filter sensitive to wavelengths of infrared light centered at 938 nanometers. The image was captured at a distance of about 1.7 million kilometers or approximately 1 million miles from Titan. The image is centered toward the Saturn-facing hemisphere of the moon and north is up and rotated 35 degrees to the left.
The infrared images are appropriate to identify cloud formations such as cloud streaks or cyclones but this view doesn't reveal any sign of clouds. That suggests that the clouds rapidly dissipate over time: the mid-latitude bright cloud streaks don't appear in this view and the south polar cloud formations are not visible. Bright cloud streaks have occasionally been spotted by the Cassini probe and Earth-based telescopes in this area toward the bottom of Titan's disk. The survey of those meteorological phenomena will undoubtedly help scientists better understand Titan's weather and climate: the radar and infrared data, combined, turn out to be very complementary and useful in unveiling topographic or meteorological features.
In this hemisphere, one can clearly notice the dark regions of Fensal and Aztlan in the lower left of the view as well as the bright intermediary region Quivira. One can also spot the bright, circular patch of Sinlap in the east of Fensal. The east part of the bright Xanadu appears in the lower left of the view, to the west of Fensal / Aztlan. To the far-east of the hemisphere ( upper right of the disk ), one can also identify the regions of Aaru and Senkyo.

Image source: NASA, JPL

The natural color image above which combines views taken using red, green and blue spectral filters was obtained with the Cassini probe wide-angle camera on October 26, 2007 at a distance of about 2.7 million kilometers ( 1.7 million miles ) from Titan and 1.5 million kilometers ( 920,000 miles ) from Saturn. The spacecraft looks toward the unilluminated side of the rings from less than a degree above the ringplane.
Saturn and its rings show their immensity on the right of the view and four natural satellites of the Gas Giant can be identified on the panorama. The biggest moon, Titan, is clearly visible above the ringplane with its opaque, orange atmosphere and its darker winter hemisphere.
Beneath and left of Titan glides Janus ( 181 kilometers or 113 miles across ), close to the ringplane. Near the planet and below the rings is Mimas, a bright, white dot 397 kilometers or 247 miles across. And between Janus and Mimas, one can discern a faint speck emerging from the rings which corresponds to the small moon Prometheus ( 102 kilometers or 63 miles across ).
One can notice that the coloration of Saturn's northern hemisphere has significantly changed since the Cassini probe's arrival in orbit in mid-2004. It might be linked to seasonal phenomena.
Titan evolves at a mean distance of roughly 1,221,830 kilometers ( 763,644 miles ) from Saturn. The moon is inclined by 0.34854 degrees to Saturn's equator which implies that the rings almost appear edge-on from a Titan observer. Saturn's equatorial inclination to its orbit is 26.73 degrees.

Image source: NASA, JPL

This set of radar images was obtained by the radar mapper onboard the Cassini probe during the final Titan flyby of the original four-year tour on May 28, 2008. The view in the lower left of the mosaic is a targeted zoom of the upper image. The radar instrument unveils the border of the region Xanadu as the bright-dark boundary running from the upper left to lower right. This area is located at 15 degrees south latitude and 121 degrees west longitude and it is roughly 450 kilometers ( 280 miles ) across. North is up.
The striking feature in this image is the presence of a set of bright, wide meandering channels apparently originating from the rough, hilly region of Xanadu. Three large, sinuous drainage channels oriented from north to south are clearly identified. The two brightest channels undoubtedly seem to flow out of the rough, bright area because they are wider to the north at the edge between Xanadu and the relatively dark and smooth terrain.
The bright drainage channels are most likely dry riverbeds because of their relatively high reflectivity. Two slightly bright channels to the extreme left of the image and in its center appear to be more eroded or older river beds. Their rough and bright appearance is probably due to the presence of icy layers or sediment deposits on the channel floors ( carbon dioxide, water ice...).
Some narrow bright or dark channels with invariable widths can also be spotted. The dark appearance is likely to reveal still flowing rivers or riverbeds with finer-grained sediment deposits. Some channels are as wide as 5 kilometers ( around 3 miles ) which is roughly the size of the River Thames at its mouth east of London and some rivers may be several hundred meters, or feet, deep.
It's very likely that the fluid that carved the drainage channels is made of hydrocarbon molecules such as methane and ethane. The area may experience strong and infrequent rainstorms, generating these branching networks and the evaporation of liquids may leave riverbeds over time, similar to earthly arroyos.
Two relatively dark patches can be spotted in Xanadu close to the border and the channels. Do they represent methane, ethane lakes ? Do they represent a source to the formation of the drainage channels ? Or are they cryovolcanic in nature ?

Image source: NASA, JPL

This artist impression proposed by NASA and JPL is supposed to represent one of the Titan lakes containing liquid hydrocarbons including ethane which has been positively identified in Ontario Lacus, the giant kidney-shape lake situated in the south polar region of the Saturn moon. Ethane has been clearly detected thanks to the analysis of the infrared views of Ontario Lacus. The hydrocarbon compound is probably mixed with nitrogen and other light hydrocarbons like methane or acetylene.
The lake above is represented as a very smooth lake. As the summer season in the southern hemisphere is about to come to an end, Ontario Lacus is presumably experiencing a partial evaporation process which implies that the lake is on the verge of reaching its minimum size.

Image source: NASA, JPL

This infrared image was captured with the Cassini probe narrow-angle camera ( Image Science Subsystem ) on April 26, 2008 using a spectral filter sensitive to wavelengths of infrared light centered at 938 nanometers. The view focuses on Titan's north polar region. The image unveils striking atmospheric features: bright clouds are encircling the north polar region. Some high-altitude ethane clouds engulfing the north pole had already been identified: the cloud formation had a spiral shape similar to a giant hurricane. This time, parallel cloud bands or strips also seem to move along a circular path around the north polar region.
This finding strengthens the hypothesis that the lakes, seas and rivers in that area are closely linked to meteorological phenomena. There is another hypothesis according to which bodies of liquid are in part generated by a subsurface ocean or cryovolcanism. No doubt that there are heavy showers and thunderstorms in the particular high northern latitudes. Moreover, the image shows that an extended, high altitude haze hovers above the limb of the moon at top of the image.

Image source: NASA, JPL

This global view of Titan was obtained with the Cassini spacecraft wide-angle camera in visible blue light on May 28, 2008. The image was captured at a phase angle or Sun-Titan-spacecraft angle of 89 degrees. The north of the Saturnian moon is up in this view. Titan's atmosphere is very complex, deep, thick, dense and opaque in visible light. This view unveils banding in the atmosphere of the northern hemisphere, atmospheric bands which appear parallel to the equator, similar to what is observed on gas giants like Jupiter or Saturn. Titan's atmosphere presents some similarities with Venus' atmosphere: both atmospheres undergo the phenomenon of "super rotation". In other words, the atmospheres of those two worlds rotate faster than the surface revealing a sharp disconnection between the movement of the gas blanket and that of the crust or the surface.

Image source: NASA, JPL

This set of radar images which were obtained in different places of Titan's surface enables us to compare two circular features definitely identified as impact craters. Both views are around 350 kilometers wide ( 217 miles ). The crater on the right, Sinlap, first spotted in 2005, is approximately 80 kilometers ( 50 miles ) in diameter and is estimated to be about 1,300 meters deep ( 984 feet ). One can note that the radar illumination comes from above and that the crater appears dark and bright in its surrounding in infrared images. Therefore, the meteor must have hit a bright area.
The feature on the left was captured by the radar instrument onboard the Cassini probe during the flyby of May 12, 2008. The apparent crater is roughly 112 kilometers in diameter ( 70 miles ) and is located at about 26 degrees north, 200 degrees west in the bright region called Dilmun, approximately 1000 kilometers ( 600 miles ) north of the Huygens landing site. The radar illumination also comes from above. The rims of the crater are not well defined, appear irregular which tends to suggest that the crater has undergone significant erosive processes. Some rim segments probably collapsed onto the floor. The inner part of the crater seems relatively flat and non uniform with different materials. Two small bright spots in the middle of the crater reveal what is supposed to be a central peak formation whereas Sinlap shows a single bright dot in its center. The ejecta blanket surrounding the newly discovered crater appears less prominent than that of the Sinlap crater. Eventually, the crater of the region Dilmun turns out to be more degraded than Sinlap, located roughly at a similar latitude. As a result, one can postulate that it is likely older than Sinlap.
Titan unveils a relatively small amount of impact craters on its surface: the feature in Dilmun is only the fourth landform identified as an impact crater and fewer than 100 features are regarded as possible impact craters. Titan's deep and dense atmosphere acts as a shied against the extraterrestrial bodies which are likely to crash onto the surface. The atmosphere burns up the meteorites. Any crater is likely to be altered or erased by erosion, wind driven motion of sand or icy volcanism.

Image source: NASA, JPL

This radar portion was captured by the Cassini spacecraft's radar instrument during the Titan flyby on May 12, 2008. The view is centered at 2 degrees south latitude, 127 degrees west longitude in the mountainous region named Xanadu. The white arrow shows the direction of radar illumination. Three parallel ridges as well as a circular feature are clearly visible in the image. One can notice some similarities between those ridges and mountain chains identified during a flyby in October 2005 at similar latitudes but roughly 90 degrees to the west, just west of Shangri-La. In both regions, mountain chains or ridges follow the same direction, that is west-to-east and are spaced around 50 kilometers ( 30 miles ) apart.
How to explain these topographic features ? It's very likely that it is simply a tectonic phenomenon. The ridges dominate the area in height and are accompanied by a very rough, rugged terrain in their surrounding. They are separated by approximately the same spacing which is typical of regions that have been extended or compressed over large portions. One can suppose notably that the mountain ranges are separated blocks of broken or faulted crust. A parallel can be drawn with plate tectonics on Earth. We have many sources of comparison on Earth regarding tectonics: for instance, the western United States Basin and Range Province emerged by extension. The orientation of the mountains suggests that tectonic forces have pushed in a north to south direction at Titan's equatorial region with symmetrical effects on Titan's crust.
The high reflectivity of the elevated terrain implies that the materials are fractured or blocky at the radar wavelength ( 2.17 centimeters or about 1 inch ). The west-to-east thin dark lines along the ridges which appear along the south sides of the mountain chains are likely prominent cliffs or scarps, a few hundred meters high ( several hundred feet ) on the basis of preliminary estimates of slopes. The dark appearance can be explained by shadowing from the radar illumination.
A few dark circular patches can also been spotted on this radar view. At bottom center, one can notice, notably, a well-defined dark circular feature, roughly 20 km in diameter ( 12 miles ). It is likely an impact crater made up of a smooth material.

Image source: NASA, JPL

This combination of maps reveals, notably, topographic features in Titan's north polar region. The image on the left corresponds to a mosaic of combined radar images captured by the Cassini spacecraft during several flybys. The colors have been artificially added to emphasize the contrast between radar-dark areas believed to be bodies of liquid ( shown in blue and dark ) and the relatively radar-bright dry land areas appearing in shades of brown. The darker the radar scan of the pool, the deeper it is expected to be. The brighter the radar scan of the terrain, the drier it is supposed to be. A brighter spot or line in the radar map can also be interpreted as a mountain, a hill or an elevated terrain. The topographic features of what appear to be lakes or seas clearly start to appear above 60 degrees north latitude as the false color mosaic shows. The liquid areas are most likely made up of methane, ethane and dissolved nitrogen.
The two "knife-shaped" views to the right represent a portion of the false-color radar mosaic, surrounded by a blue line. This north polar region is 1,700 by 200 kilometers ( 1.050 by 125 miles ) in area. The upper right view corresponds to the synthetic aperture radar image acquired during Cassini's April 11, 2007 flyby. At least four bodies of liquid are clearly visible. The second radar patch, from west to east, appears to be the northern portion of what might be the biggest sea in Titan's northern hemisphere. A boat could sail more than 400 km from the west shore to reach the east shore. A giant island appears to cover the northern portion of the sea. In its northern rims, the sea level seams to be less deep than in the south rim because the radar signal is not as weak in the north. A branching or dendritic system of drainage channels clearly appears in the third sea or estuary ( from left to right ). To the west, some steep-sided depressions can be identified. They appear bright in the radar image. Probably that they represent empty pools, dried up lakes. One can also envisage that they are volcanic in origin or that they are the outcome of dissolution of surface materials by fluids.
The lower right strip represents the topographic map of the radar strip. It was obtained by combining data from the April 11, 2007 flyby with data of a previous flyby on February 22, 2007. Thus, the relief appears with blue and violet areas representing lower elevation terrain while green, yellow and red regions are higher elevation areas. The elevations are based on the mean for Titan's radius of 2,575 kilometers ( 1,600 miles ). The outcome reveals that the total range of elevations is only around 1.3 kilometers ( 0.8 miles ) which implies that surface slopes are very gentle, a few degrees or less. The topographic analysis also suggests that the bright areas are high relative to the darker areas, thought to be pools of hydrocarbons. It strengthens, obviously, the idea of ethane / methane pools.

Image source: NASA, JPL

This natural color view of Titan, approaching the brilliant limb of Saturn, was obtained on January 29, 2008 with the Cassini probe narrow-angle camera, at a distance of about 2.3 million kilometers from Titan ( 1.4 million miles ). It combines images taken using red, green and blue spectral filters. The images were captured just minutes after a wide-angle image showing the tiny moon of Titan near the giant ring planet. Although their appearance presents some similarities such as an opaque and uniform ( or almost uniform ) atmosphere, their internal nature is very different: Saturn is a gas giant while Titan is an icy moon. The atmosphere of Titan is dominated by molecular nitrogen and methane while Saturn's atmosphere is mainly composed of hydrogen and helium with minor gases such as methane and ammonia.
This view reveals a significant difference in the color of the two bodies: Saturn has a yellowish-brown color whereas Titan has an orange or brownish color due to its haze, made up of organic material. And Saturn appears well brighter.

Image source: NASA, JPL

This infrared view of the biggest Saturn moon was captured with the Cassini spacecraft narrow-angle camera on January 20, 2008 using a combination of spectral filters sensitive to wavelengths of polarized infrared light centered at 938 and 746 nanometers. The image was obtained at a Sun-Titan-spacecraft, or phase, angle of 58 degrees. North, here, is up and rotated 26 degrees to the right.
Near the center of the view, at the same longitude as Hotei Arcus, above the north east of the bright region Xanadu or in the north west above Fensal, one can spot the circular, 400-kilometer wide impact feature Menrva with its dark ring. It is situated a little below 30 degrees north latitude and 90 degrees west longitude.
The infrared image also reveals a bright streak of cloud at 60 degrees north latitude. This is the second time that the Cassini probe identifies clouds at that latitude. During a flyby of February 2007, a cirrus-like cloud had been spotted at the same latitude. This cirrus-like cloud runs at the boundary of Titan's northern wetlands where a quasi sea has been probably spotted in VIMS images.

Image source: NASA, JPL

This natural color view of Titan, partly illuminated, was captured with the Cassini spacecraft wide-angle camera on January 5, 2008. It combines images using red, green and blue spectral filters and it was obtained at a Sun-Titan-spacecraft, or phase, angle of 128 degrees. North on this Saturn-moon view is up and rotated 30 degrees to the right, tilting slightly away from the spacecraft. The thick and dense atmospheric layer makes the Saturn moon completely opaque in the visible spectrum. The orange haze is made of complex organic molecules. In the upper atmosphere, methane molecules are being broken apart by solar ultraviolet light and the resulting molecules combine or recombine to form compounds like ethane, acetylene or hydrogen cyanide.The blue color in the upper atmosphere is the outcome of that photolysis: the haze preferentially scatters blue and ultraviolet wavelengths of light.

Image source: NASA, JPL

This ultraviolet view of Titan was captured with the Cassini spacecraft narrow-angle camera during a recent flyby on December 20, 2007 using a spectral filter sensitive to wavelengths of ultraviolet light centered at 338 nanometers. The image was obtained at a Sun-Titan-spacecraft, or phase, angle of 133 degrees. The atmospheric layers can be well distinguished in the ultraviolet spectrum. Titan's atmosphere appears very complex with multiple haze layers. The gas blanket is well deeper and more massive than the Earth's atmosphere. Some complex organic molecules are being produced in Titan's atmosphere through the interactions with ultraviolet radiations. A detached, external haze layer is clearly visible in Titan's upper atmosphere in this image.

Image source: NASA, JPL

The synthetic aperture radar image, above, was captured by the Cassini probe during its pass over Titan's south pole on December 20, 2007. The view is centered near 76.5 degrees south, 32.5 degrees west and covers an area of 620 kilometers by 270 kilometers ( 385 miles by 170 miles ).
Some relatively clear topographic contrasts can be identified on this radar portion. A rough, rugged terrain surrounds smooth areas, especially in the south part of the image. An erosional process due to flowing liquids is clearly visible: in the upper part of the strip, on the right, a dark area dominates a landscape carved by what are believed to be hydrocarbon liquids. Some branching drainage channels run southward. It seems that the dark regions in the upper part and in the lower part are interconnected via a network of rivers. The dark patches are not very absorbing which tends to suggest that if they are wet, the depth of the pseudo-lakes is not very high. The rugged terrain made of apparent hills seems to be drawn, corroded by liquid flows, resulting in a maze of rivers which appear to be dried up, currently. In the middle of the view, a smooth terrain appears very reflective, bright which suggests that it is a basin whose liquid content has evaporated.
The origin of the topographic features remains a subject of debate: methane rainstorms may play a role. Sapping, that is subsurface methane rising to erode the surface, is also a phenomenon likely to have a significant impact on the landscape. The multiple valleys in the rough terrain may also be caused by tectonic processes, such as rifting even if erosional processes due to liquid methane or ice seem more realistic.

Image source: NASA, JPL