Titan's Dark Side

NASA's Cassini spacecraft looks towards the dark side of Saturn's largest moon, Titan, capturing the blue halo caused by a haze layer that hovers high in the moon's atmosphere. The haze that permeates Titan's atmosphere scatters sunlight and produces the orange color seen here. More on Titan's orange and blue hazes can be found at PIA14913.

This view looks towards the side of Titan (3,200 miles or 5,150 kilometers across) that leads in its orbit around Saturn. North on Titan is up and rotated 40 degrees to the left. Images taken using red, green and blue spectral filters were combined to create this natural-color view. The images were taken with the Cassini spacecraft narrow-angle camera on November 3, 2013.

The view was acquired at a distance of approximately 2.421 million miles (3.896 million kilometers) from Titan. Image scale is 14 miles (23 kilometers) per pixel.

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

Note: For more information, see Cassini Sees Saturn and Moons in Holiday Dress.

Lakes and Seas of Titan

Using a special spectral filter, the high-resolution camera aboard NASA's Cassini spacecraft was able to peer through the hazy atmosphere of Saturn's moon Titan. It captured this image, which features the largest seas and some of the many hydrocarbon lakes that are present on Titan's surface. Titan is the only place in the solar system, other than Earth, that has stable liquids on its surface. In this case, the liquid consists of ethane and methane rather than water. Figure 1 indicates the names assigned to the visible features. Titan's largest sea is Kraken Mare.

For more information on Titan's hydrocarbon lakes see PIA17472 and PIA17473.

This view looks towards the side of Titan (3,200 miles or 5,150 kilometers across) that leads in its orbit around Saturn. North on Titan is up and rotated 36 degrees to the left. Images taken using red, green and blue spectral filters were combined to create this natural-color view. The images were taken with the Cassini spacecraft narrow-angle camera on October 7, 2013.

The view was acquired at a distance of approximately 809,000 miles (1.303 million kilometers) from Titan. Image scale is 5 miles (8 kilometers) per pixel.

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

Note: For more information, see Cassini Sees Saturn and Moons in Holiday Dress.

Titan's South Polar Vortex

Slipping into shadow, the south polar vortex at Saturn's moon Titan still stands out against the orange and blue haze layers that are characteristic of Titan's atmosphere. Images like this, from NASA's Cassini spacecraft, lead scientists to conclude that the polar vortex clouds form at a much higher altitude -- where sunlight can still reach -- than the lower-altitude surrounding haze.

For another color image of the south polar vortex on Titan, see PIA14919. For a movie of the vortex, see PIA14920.

This view looks towards the trailing hemisphere of Titan (3,200 miles or 5,150 kilometers across). North on Titan is up and rotated 17 degrees to the left. Images taken using red, green and blue spectral filters were combined to create this natural-color view. The image was taken with the Cassini spacecraft narrow-angle camera on July 30, 2013.

The view was acquired at a distance of approximately 895,000 miles (1.441 million kilometers) from Titan. Image scale is 5 miles (9 kilometers) per pixel.

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

Note: For more information, see Cassini Sees Saturn and Moons in Holiday Dress.

Saturn's Approaching Southern Winter

Winter is approaching in the southern hemisphere of Saturn and with this cold season has come the familiar blue hue that was present in the northern winter hemisphere at the start of NASA's Cassini mission. The changing blue hue that we have learned marks winter at Saturn is likely due to reduction of ultraviolet sunlight and the haze it produces, making the atmosphere clearer and increasing the opportunity for Rayleigh scattering (scattering by molecules and smaller particles) and methane absorption: both processes make the atmosphere blue. The small black dot seen to the right and up from image center, within the ring shadows of the A and F rings, is the shadow of the moon, Prometheus. For an image showing winter in the northern hemisphere see PIA08166.

This view looks toward the unilluminated side of the rings from about 44 degrees below the ring plane. Images taken using red, green and blue spectral filters were combined to create this natural color view. The images were taken with the Cassini spacecraft wide-angle camera on July 29, 2013.

This view was acquired at a distance of approximately 1.003 million miles (1.615 million kilometers) from Saturn. Image scale is 58 miles (93 kilometers) per pixel.

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

Note: For more information, see Cassini Sees Saturn and Moons in Holiday Dress.

Saturn's North Polar Hexagon and Hurricane in Natural Color

The globe of Saturn, seen here in natural color, is reminiscent of a holiday ornament in this wide-angle view from NASA's Cassini spacecraft. The characteristic hexagonal shape of Saturn's northern jet stream, somewhat yellow here, is visible. At the pole lies a Saturnian version of a high-speed hurricane, eye and all.

To learn more about Saturn's north polar region see PIA14944 and PIA14945.

This view is centered on terrain at 75 degrees north latitude, 120 degrees west longitude. Images taken using red, green and blue spectral filters were combined to create this natural-color view. The images were taken with the Cassini spacecraft wide-angle camera on July 22, 2013.

This view was acquired at a distance of approximately 611,000 miles (984,000 kilometers) from Saturn. Image scale is 51 miles (82 kilometers) per pixel.

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

Note: For more information, see Cassini Sees Saturn and Moons in Holiday Dress.

Titan and Rhea

Saturn's largest and second largest moons, Titan and Rhea, appear to be stacked on top of each other in this true-color scene from NASA's Cassini spacecraft.

The north polar hood can be seen on Titan (3,200 miles or 5,150 kilometers across) appearing as a detached layer at the top of the moon on the top right. See PIA08137 to learn more about Titan's atmosphere and the north polar hood.

This view looks toward the Saturn-facing side of Rhea (949 miles or 1528 kilometers across). North on Rhea is up and rotated 35 degrees to the right.

Images taken using red, green and blue spectral filters were combined to create this natural-color view. The images were acquired with the Cassini spacecraft narrow-angle camera on June 16, 2011, at a distance of approximately 1.1 million miles (1.8 million kilometers) from Rhea and 1.5 million miles (2.5 million kilometers) from Titan. Image scale is 7 miles (11 kilometers) per pixel on Rhea and 9 miles (15 kilometers) on Titan.

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

Note: For more information, see Cassini Sees Saturn and Moons in Holiday Dress.

Titan Ringlet and Bending Wave in Saturn's Rings

A dynamical interplay between Saturn's largest moon, Titan, and its rings is captured in this view from NASA's Cassini spacecraft.

At every location within Saturn's rings, particles orbit with a particular period, or rhythm. This image is focused on two separate and nearby locations in the rings where those rhythms are in synchrony with different aspects of Titan's 16-day orbit, creating signature effects that point from a distance back towards Titan.

The Titan Ringlet, embedded within the Colombo Gap at the center of this image, is slightly oval-shaped and always points its long axis towards Titan. The behavior and orientation of the ringlet are controlled by a gravitational resonance between Titan's 16-day orbit and the rate at which ring particles' oval-shaped paths rotate ("precess") around the planet. Because the particles' orbit precession is sensitively tied to Saturn's internal gravity structure, the radial location of the Titan Ringlet supplies scientists with the best available measurement of the outer layers of Saturn's interior.

Just inward of the gap is a very narrow feature that transitions from bright at the top of the image to dark at the bottom. This is a bending, or vertical, wave generated by a similar resonance with Titan, but this time it involves a synchronicity between the out-of-plane motion of Titan, which is on an inclined (tilted) orbit and similar motions of the ring particles with their own inclined orbits. In this image, taken near Saturn's 2009 equinox when sunlight hit the rings nearly edge-on, the vertical structure of the bending wave is obvious because of shadows giving it an unusual bright-to-dark appearance.

Also visible because of the shallow illumination angle is the vertical corrugation that crosses the entire C ring. This is the after-effect of a large impactor that is believed to have hit the inner Saturnian rings around the year 1983. Looking like a pattern of faint stripes, the corrugation is best seen on the right-hand side of the image, where other ring structure is sparse.

This view looks toward the sunlit side of the rings from about 9 degrees above the ring plane. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on September 20, 2009.

The view was obtained at a distance of approximately 288,000 miles (463,000 kilometers) from Saturn and at a sun-Saturn-spacecraft, or phase, angle of 13 degrees. Image scale is 1 mile (2 kilometers) per pixel.

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

Note: For more information, see Cassini Sees Saturn and Moons in Holiday Dress.

Iapetus

Iapetus is a moon of extreme contrasts. The light and dark features give the moon a distinctive "yin and yang" appearance. Scientists believe that a runaway migration of ice on the surface, triggered by a preferential initial darkening and consequential warming of the leading hemisphere of the moon by infalling debris from the outer moon Phoebe, may be responsible for the unusual and striking appearance.

For more on Iapetus (914 miles, or 1,471 kilometers across), see this press release about theories regarding this moon's unique color dichotomy.

This view looks toward the Saturn-facing hemisphere of Iapetus. North on Iapetus is up and rotated 30 degrees to the right. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on August 30, 2013.

The view was obtained at a distance of approximately 1.5 million miles (2.5 million kilometers) from Iapetus. The raw image scale is 9 miles (15 kilometers) per pixel. This image has been magnified by a factor of 1.5.

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

Saturn's North Polar Hexagon

Earth's jet stream is a subject of intense interest and concern thanks to its effects on our weather. Saturn's polar jet stream, seen here, causes no such worries for Earthlings, so we can simply marvel at its graceful form.

This atmospheric feature was first observed by Voyager and was dubbed 'the hexagon'. To see more of this feature, see PIA10486 and PIA11682.

This view looks toward the north pole of Saturn from about 53 degrees above the ringplane. The image was taken with the Cassini spacecraft wide-angle camera on July 23, 2013 using a spectral filter sensitive to wavelengths of near-infrared light centered at 752 nanometers.

The view was obtained at a distance of approximately 590,000 miles (949,000 kilometers) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 52 degrees. Image scale is 35 miles (57 kilometers) per pixel.

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

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