Titan - Extraterrestrial Land of Lakes

This colorized flyover movie from NASA's Cassini mission shows the two largest seas on Saturn's moon Titan and nearby lakes. Titan is the only world in our solar system other than Earth that has stable liquid on its surface. The liquid in Titan's lakes and seas is mostly methane and ethane.

The flight path starts at Titan's largest sea, Kraken Mare (about 680 miles or 1,100 kilometers long), and passes over the second largest sea, Ligeia Mare. Titan seas are named after sea monsters in world mythology. Then, there is an area with no topographical data and the flight path crosses an area with smaller lakes.

Lakes in this area are about 30 miles (50 kilometers) across or less.

Data for the movie was obtained by Cassini's radar instrument from 2004 to 2013. Heights of features were exaggerated 10 times. In this color scheme, liquids appear blue and black. Land areas appear yellow to white. A haze was added to simulate the Titan atmosphere.

Straight lines in the images are artifacts of how Cassini obtained the data.

The topographic mapping of Titan using stereo radar images was performed by the U.S. Geological Survey in Flagstaff, Arizona. The animation was created at JPL.

Video credit: NASA/JPL-Caltech/ASI/USGS

Note: For more information, see PIA17655: Titan's North and NASA's Cassini Spacecraft Reveals Clues About Saturn Moon

Prometheus and the Rings

Saturn's moons create art on the canvas of Saturn's rings with gravity as their tool. Here Prometheus is seen sculpting the F ring while Daphnis (too small to discern in this image) raises waves on the edges of the Keeler gap.

Prometheus (53 miles, or 86 kilometers across) is just above image center while Daphnis (5 miles, or 8 kilometers across), although too small to see in its location in the Keeler gap just to the right of center, can be located by the waves it creates on the edges of the gap. Prometheus and stars have been brightened by a factor of 2 relative to the rest of the image to enhance their visibility. There are 20 stars visible in this image.

This view looks toward the unilluminated side of the rings from about 53 degrees below the ringplane. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on August 25, 2013.

The view was acquired at a distance of approximately 1.2 million miles (1.9 million kilometers) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 111 degrees. Image scale is 7 miles (11 kilometers) per pixel.

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

Saturn's North Polar Hexagon

This colorful view from NASA's Cassini mission is the highest-resolution view of the unique six-sided jet stream at Saturn's north pole known as "the hexagon." This movie, made from images obtained by Cassini's imaging cameras, is the first to show the hexagon in color filters, and the first movie to show a complete view from the north pole down to about 70 degrees north latitude.

Scientists can see the motion of a wide variety of cloud structures that reside within the hexagon in this movie. There is a massive hurricane tightly centered on the north pole, with an eye about 50 times larger than the average hurricane eye on Earth. (More information about that Saturn hurricane is at PIA14947.) Numerous small vortices are also present, which appear as reddish ovals. Some of these vortices spin clockwise while the hexagon and hurricane spin counterclockwise. Some of those smaller features are swept along with the jet stream of the hexagon, as if on a racetrack. The biggest of these vortices, seen near the lower right corner of the hexagon and appearing whitish, spans about 2,200 miles (3,500 kilometers), approximately twice the size of the largest hurricane on Earth.

The differences in this version of the movie, in which different wavelengths of light from ultraviolet to visible to infrared have been assigned colors, show a distinct contrast between the types of atmospheric particles inside and outside the hexagon. Inside the hexagon there are fewer large haze particles and a concentration of small haze particles, while outside the hexagon, the opposite is true. The jet stream that makes up the hexagon seems to act like a barrier, which results in something like the "ozone hole" in the Antarctic.

This movie shows a view from directly over the north pole, keeping up with the rotation of the planet so that all the motion seen on the screen is the motion of the hexagonal jet stream or the storms inside of it, without any added motion from the spinning of the planet itself. The original images were re-projected to show this polar view.

High-resolution views of the hexagon have only recently become possible because of the changing of the seasons at Saturn and changes in the Cassini spacecraft's orbit. The north pole was dark when Cassini first arrived in July 2004. The sun really only began to illuminate the entire interior of the hexagon in August 2009, with the start of northern spring. In late 2012, Cassini began making swings over Saturn's poles, giving it better views of the hexagon.

The eight frames of the movie were captured over 10 hours on December 10, 2012. Each of the eight frames consists of 16 map-projected images (four per color filter, and four filters per frame) so the movie combines data from 128 images total.

In this color scheme, scientists assigned red to the 0.750-micron part of the light spectrum (near infrared). This part of the spectrum penetrates the high-altitude haze layer to sense the top of tropospheric cloud deck. They assigned green to the 0.727-micron part of the light spectrum that senses the upper tropospheric haze (a near-infrared wavelength corresponding to a methane absorption band). They assigned blue to the sum of blue and ultraviolet broadband filters -- combined, this blue channel covers between 0.400 and 0.500 microns (covering very near ultraviolet to blue in visible light). This part of the spectrum is sensitive to small aerosols.

To human eyes, the hexagon and north pole would appear in tones of gold and blue. See PIA14945 for a still image of the area in natural color.

Video credit: NASA/JPL-Caltech/SSI/Hampton University

Note: For more information, see PIA17653: Hexagon in Silhouette, PIA17654: Looking Down on the Hexagon in Infrared, and NASA's Cassini Spacecraft Obtains Best Views of Saturn Hexagon.

Titan's South Polar Vortex

The sunlit edge of Titan's south polar vortex stands out distinctly against the darkness of the moon's unilluminated hazy atmosphere. The Cassini spacecraft images of the vortex led scientists to conclude that its clouds form at a much higher altitude -- where sunlight can still reach -- than the surrounding haze.

Titan (3,200 miles, or 5,150 kilometers across) is Saturn's largest moon. For a color image of the south polar vortex on Titan, see PIA14919. For a movie of the vortex, see PIA14920.

This view looks toward the trailing hemisphere of Titan. North on Titan is up and rotated 32 degrees to the left. The image was taken with the Cassini spacecraft narrow-angle camera on July 14, 2013 using a spectral filter sensitive to wavelengths of near-infrared light centered at 938 nanometers.

The view was obtained at a distance of approximately 808,000 miles (1.3 million kilometers) from Titan and at a Sun-Titan-spacecraft, or phase, angle of 82 degrees. Image scale is 5 miles (8 kilometers) per pixel.

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

Epimetheus and Daphnis

While the moon Epimetheus passes by, beyond the edge of Saturn's main rings, the tiny moon Daphnis carries on its orbit within the Keeler gap of the A ring. Although quite different in size, both moons create waves in the rings thanks to their gravitational influences.

Epimetheus (70 miles, or 113 kilometers across) is visible at the lower-right of the image, and Daphnis (5 miles, or 8 kilometers across) is barely visible at one pixel wide just below-right of the image center. A close inspection of the image also reveals the waves Daphnis creates on the edges of the Keeler gap.

This view looks toward the unilluminated side of the rings from about 2.6 degrees below the ringplane. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on June 28, 2013.

The view was acquired at a distance of approximately 808,000 miles (1.3 million kilometers) from Daphnis and at a Sun-Daphnis-spacecraft, or phase, angle of 28 degrees. Image scale is 5 miles (8 kilometers) per pixel.

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

Saturn in Infrared

To the Cassini spacecraft's infrared eyes, Saturn's graceful clouds sometimes take on the appearance of an impressionist's painting of the giant planet.

This view looks toward the sunlit side of the rings from about 18 degrees above the ringplane. The image was taken with the Cassini spacecraft wide-angle camera on August 12, 2013 using a spectral filter sensitive to wavelengths of near-infrared light centered at 728 nanometers.

The view was acquired at a distance of approximately 994,000 miles (1.6 million kilometers) from Saturn. Image scale is 57 miles (92 kilometers) per pixel.

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

Saturn, with Earth, Venus and Mars

On July 19, 2013, in an event celebrated the world over, NASA's Cassini spacecraft slipped into Saturn's shadow and turned to image the planet, seven of its moons, its inner rings -- and, in the background, our home planet, Earth.

With the sun's powerful and potentially damaging rays eclipsed by Saturn itself, Cassini's onboard cameras were able to take advantage of this unique viewing geometry. They acquired a panoramic mosaic of the Saturn system that allows scientists to see details in the rings and throughout the system as they are backlit by the sun. This mosaic is special as it marks the third time our home planet was imaged from the outer solar system; the second time it was imaged by Cassini from Saturn's orbit; and the first time ever that inhabitants of Earth were made aware in advance that their photo would be taken from such a great distance.

With both Cassini's wide-angle and narrow-angle cameras aimed at Saturn, Cassini was able to capture 323 images in just over four hours. This final mosaic uses 141 of those wide-angle images. Images taken using the red, green and blue spectral filters of the wide-angle camera were combined and mosaicked together to create this natural-color view. A brightened version with contrast and color enhanced (Figure 1), a version with just the planets annotated (Figure 2), and an annotated version (Figure 3) are shown above.

This image spans about 404,880 miles (651,591 kilometers) across.

The outermost ring shown here is Saturn's E ring, the core of which is situated about 149,000 miles (240,000 kilometers) from Saturn. The geysers erupting from the south polar terrain of the moon Enceladus supply the fine icy particles that comprise the E ring; diffraction by sunlight gives the ring its blue color. Enceladus (313 miles, or 504 kilometers, across) and the extended plume formed by its jets are visible, embedded in the E ring on the left side of the mosaic.

At the 12 o'clock position and a bit inward from the E ring lies the barely discernible ring created by the tiny, Cassini-discovered moon, Pallene (3 miles, or 4 kilometers, across). (For more on structures like Pallene's ring, see PIA08328). The next narrow and easily seen ring inward is the G ring. Interior to the G ring, near the 11 o'clock position, one can barely see the more diffuse ring created by the co-orbital moons, Janus (111 miles, or 179 kilometers, across) and Epimetheus (70 miles, or 113 kilometers, across). Farther inward, we see the very bright F ring closely encircling the main rings of Saturn.

Following the outermost E ring counter-clockwise from Enceladus, the moon Tethys (662 miles, or 1,066 kilometers, across) appears as a large yellow orb just outside of the E ring. Tethys is positioned on the illuminated side of Saturn; its icy surface is shining brightly from yellow sunlight reflected by Saturn. Continuing to about the 2 o'clock position is a dark pixel just outside of the G ring; this dark pixel is Saturn's Death Star moon, Mimas (246 miles, or 396 kilometers, across). Mimas appears, upon close inspection, as a very thin crescent because Cassini is looking mostly at its non-illuminated face.

The moons Prometheus, Pandora, Janus and Epimetheus are also visible in the mosaic near Saturn's bright narrow F ring. Prometheus (53 miles, or 86 kilometers, across) is visible as a faint black dot just inside the F ring and at the 9 o'clock position. On the opposite side of the rings, just outside the F ring, Pandora (50 miles, or 81 kilometers, across) can be seen as a bright white dot. Pandora and Prometheus are shepherd moons and gravitational interactions between the ring and the moons keep the F ring narrowly confined. At the 11 o'clock position in between the F ring and the G ring, Janus (111 miles, or 179 kilometers, across) appears as a faint black dot. Janus and Prometheus are dark for the same reason Mimas is mostly dark: we are looking at their non-illuminated sides in this mosaic. Midway between the F ring and the G ring, at about the 8 o'clock position, is a single bright pixel, Epimetheus. Looking more closely at Enceladus, Mimas and Tethys, especially in the brightened version of the mosaic, one can see these moons casting shadows through the E ring like a telephone pole might cast a shadow through a fog.

In the non-brightened version of the mosaic, one can see bright clumps of ring material orbiting within the Encke gap near the outer edge of the main rings and immediately to the lower left of the globe of Saturn. Also, in the dark B ring within the main rings, at the 9 o'clock position, one can see the faint outlines of two spoke features, first sighted by NASA's Voyager spacecraft in the early 1980s and extensively studied by Cassini.

Finally, in the lower right of the mosaic, in between the bright blue E ring and the faint but defined G ring, is the pale blue dot of our planet, Earth. Look closely and you can see the moon protruding from the Earth's lower right. (For a higher resolution view of the Earth and moon taken during this campaign, see PIA14949.) Earth's twin, Venus, appears as a bright white dot in the upper left quadrant of the mosaic, also between the G and E rings. Mars also appears as a faint red dot embedded in the outer edge of the E ring, above and to the left of Venus.

For ease of visibility, Earth, Venus, Mars, Enceladus, Epimetheus and Pandora were all brightened by a factor of eight and a half relative to Saturn. Tethys was brightened by a factor of four. In total, 809 background stars are visible and were brightened by a factor ranging from six, for the brightest stars, to 16, for the faintest. The faint outer rings (from the G ring to the E ring) were also brightened relative to the already bright main rings by factors ranging from two to eight, with the lower-phase-angle (and therefore fainter) regions of these rings brightened the most. The brightened version of the mosaic was further brightened and contrast-enhanced all over to accommodate print applications and a wide range of computer-screen viewing conditions.

Some ring features -- such as full rings traced out by tiny moons -- do not appear in this version of the mosaic because they require extreme computer enhancement, which would adversely affect the rest of the mosaic. This version was processed for balance and beauty.

This view looks toward the unlit side of the rings from about 17 degrees below the ring plane. Cassini was approximately 746,000 miles (1.2 million kilometers) from Saturn when the images in this mosaic were taken. Image scale on Saturn is about 45 miles (72 kilometers) per pixel.

This mosaic was made from pictures taken over a span of more than four hours while the planets, moons and stars were all moving relative to Cassini. Thus, due to spacecraft motion, these objects in the locations shown here were not in these specific places over the entire duration of the imaging campaign. Note also that Venus appears far from Earth, as does Mars, because they were on the opposite side of the sun from Earth.

Image credit: NASA/JPL-Caltech/SSI

Note: For more information, see NASA Cassini Spacecraft Provides New View of Saturn and Earth, PIA17679: The Faces of 'Wave at Saturn' and Spectacular New View of Saturn and Earth. From earlier in the year, see Cassini to Photograph Earth From Deep Space and Cassini Releases Image of Earth Waving at Saturn.

F-Ring Mini-Jet

A single jet feature appears to leap from the F ring of Saturn in this image from the Cassini spacecraft. A closer inspection suggests that in reality there are a few smaller jets that make up this feature, suggesting a slightly more complex origin process.

These "jets," like much of the dynamic and changing F ring, are believed by scientists to be caused by the ring's particles interacting with small moons orbiting nearby.

This view looks toward the unilluminated side of the rings from about 45 degrees below the ringplane. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on June 20, 2013.

The view was obtained at a distance of approximately 870,000 miles (1.4 million kilometers) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 77 degrees. Image scale is 5 miles (8 kilometers) per pixel.

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

Tethys

The craters of Tethys tell the story of a violent history marked by impacts. The names of the craters also tell oft-violent stories: in this case, the Iliad and the Odyssey. Here, we see the craters Melanthius (near the center, at the day/night terminator), Dolius (above Melanthius), and Penelope (upper left almost over the limb). Penelope was the faithful and wise wife of the Greek hero Odysseus, Dolius was their loyal gardener, and Melanthius was Dolius' son.

This view looks toward the leading side of Tethys. North on Tethys is up and rotated 32 degrees to the right. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on May 16, 2013.

The view was obtained at a distance of approximately 684,000 miles (1.1 million kilometers) from Tethys and at a Sun-Tethys-spacecraft, or phase, angle of 63 degrees. Image scale is 4 miles (7 kilometers) per pixel. The image has been zoomed in by a factor of 1.5.

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

Quintet of Moons

Five moons pose for the international Cassini spacecraft to create this beautiful portrait with Saturn’s rings.

This view, from 29 July 2011, looks toward the northern, sunlit side of the rings from just above the ringplane.

At the far right, and obscuring Saturn itself, is the planet’s second largest moon Rhea, which spans 1528 km. Rhea is closest to Cassini in this composition, at a distance of 1.1 million kilometers. Its heavily cratered surface bears witness to a violent history, with many craters overlapping or erasing the traces of older impact events.

The nearly 400 km-wide Mimas lies just beyond, and seemingly levitates just above Saturn’s innermost rings. The outline of the moon’s large, distinguishing crater Herschel is partially covered by Rhea, but can just be made out along with numerous smaller craters.

Brightly reflective Enceladus appears above the center of the image and lies beyond the rings, at a distance of 1.8 million kilometers from Cassini. Although not visible in this image, icy Enceladus is covered with a network of frozen ridges and troughs, with plumes of ice particles jetting from fissures in its southern hemisphere.

To the lower left, tiny Pandora, just 81 km across, appears skewered by Saturn’s outer rings – in fact, it orbits between the planet’s A and F rings.

Last but not least, the irregularly shaped Janus lies at the far left of the image, several shadowy surface markings corresponding to large impact craters.

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