CASSINI LOOKS AT SATURN'S RING STRUCTURE

FROM:  NASA 

From afar, Saturn's rings look like a solid, homogenous disk of material. But upon closer examination from Cassini, we see that there are varied structures in the rings at almost every scale imaginable. Structures in the rings can be caused by many things, but often times Saturn's many moons are the culprits. The dark gaps near the left edge of the A ring (the broad, outermost ring here) are caused by the moons (Pan and Daphnis) embedded in the gaps, while the wider Cassini division (dark area between the B ring and A ring here) is created by a resonance with the medium-sized moon Mimas (which orbits well outside the rings). Prometheus is seen orbiting just outside the A ring in the lower left quadrant of this image; the F ring can be faintly seen to the left of Prometheus. This view looks toward the sunlit side of the rings from about 15 degrees above the ringplane. The image was taken in red light with the Cassini spacecraft wide-angle camera on Jan. 8, 2015. The view was obtained at a distance of approximately 566,000 miles (911,000 kilometers) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 37 degrees. Image scale is 34 miles (54 kilometers) per pixel. The Cassini mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.  Credit: NASA/JPL-Caltech/Space Science Institute.

ICE MOON HANGS ON

FROM:  NASA 

Right:  Stuck on the Rings
Like a drop of dew hanging on a leaf, Tethys appears to be stuck to the A and F rings from this perspective.

Tethys (660 miles, or 1,062 kilometers across), like the ring particles, is composed primarily of ice. The gap in the A ring through which Tethys is visible is the Keeler gap, which is kept clear by the small moon Daphnis (not visible here).
This view looks toward the Saturn-facing hemisphere of Tethys. North on Tethys is up and rotated 43 degrees to the right. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on July 14, 2014.

The view was acquired at a distance of approximately 1.1 million miles (1.8 million kilometers) from Tethys and at a Sun-Tethys-spacecraft, or phase, angle of 22 degrees. Image scale is 7 miles (11 kilometers) per pixel.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.
Credit: NASA/JPL-Caltech/Space Science Institute

SATURN'S RINGS STUDIED WITH SPECIAL LIGHT FILTER

FROM:  NASA

Although it may look to our eyes like other images of the rings, this infrared image of Saturn's rings was taken with a special filter that will only admit light polarized in one direction. Scientists can use these images to learn more about the nature of the particles that make up Saturn's rings. The bright spot in the rings is the "opposition surge" where the Sun-Ring-Spacecraft angle passes through zero degrees. Ring scientists can also use the size and magnitude of this bright spot to learn more about the surface properties of the ring particles. This view looks toward the sunlit side of the rings from about 19 degrees above the ringplane. The image was taken with the Cassini spacecraft wide-angle camera on Aug. 18, 2013 using a spectral filter sensitive to wavelengths of near-infrared light centered at 705 nanometers. The view was acquired at a distance of approximately 712,000 miles (1.1 million kilometers) from Saturn and at a Sun-rings-spacecraft, or phase, angle of 7 degrees. Image scale is 43 miles (68 kilometers) per pixel.  Image Credit-NASA-JPL-Caltech-Space Science Institute.

LITTLE BITTY PRETTY MOON

FROM: NASA

Beautiful Plumage
Like a proud peacock displaying its tail, Enceladus shows off its beautiful plume to the Cassini spacecraft's cameras.

Enceladus (313 miles, or 504 kilometers across) is seen here illuminated by light reflected off Saturn.

This view looks toward the Saturn-facing side of Enceladus. North on Enceladus is up and rotated 45 degrees to the right. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Jan. 18, 2013.

The view was acquired at a distance of approximately 483,000 miles (777,000 kilometers) from Enceladus and at a Sun-Enceladus-spacecraft, or phase, angle of 173 degrees. Image scale is 3 miles (5 kilometers) per pixel.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo. Credit: NASA/JPL-Caltech/Space Science Institute

SATURN HEX

FROM: NASA
Saturn's North Polar Hexagon
Saturn's north polar hexagon basks in the Sun's light now that spring has come to the northern hemisphere. Many smaller storms dot the north polar region and Saturn's signature rings, which appear to disappear on account of Saturn's shadow, put in an appearance in the background.

The image was taken with the Cassini spacecraft's wide-angle camera on Nov. 27, 2012 using a spectral filter sensitive to wavelengths of near-infrared light centered at 750 nanometers.

The view was acquired at a distance of approximately 403,000 miles (649,000 kilometers) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 21 degrees. Image scale is 22 miles (35 kilometers) per pixel.

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

NASA VIDEO: WHAT'S UP FOR JANUARY 2013

What's Up for January 2013
Spy Saturn, Jupiter, Venus and Mars as they make appearances next to the moon this month, making them easy and fun to spot in the sky.  Credit:  NASA.

NASA'S CASSINI FINDS SATURN'S MOON PHOEBE HAS PLANET-LIKE QUALITIES

FROM:  NASA
WASHINGTON -- Data from NASA's Cassini mission reveal Saturn's moon
Phoebe has more planet-like qualities than previously thought.

Scientists had their first close-up look at Phoebe when Cassini began
exploring the Saturn system in 2004. Using data from multiple
spacecraft instruments and a computer model of the moon's chemistry,
geophysics and geology, scientists found Phoebe was a so-called
planetesimal, or remnant planetary building block. The findings
appear in the April issue of the Journal Icarus.

"Unlike primitive bodies such as comets, Phoebe appears to have
actively evolved for a time before it stalled out," said Julie
Castillo-Rogez, a planetary scientist at NASA's Jet Propulsion
Laboratory (JPL) in Pasadena, Calif. "Objects like Phoebe are thought
to have condensed very quickly. Hence, they represent building blocks
of planets. They give scientists clues about what conditions were
like around the time of the birth of giant planets and their moons"

Cassini images suggest Phoebe originated in the far-off Kuiper Belt,
the region of ancient, icy, rocky bodies beyond Neptune's orbit. Data
show Phoebe was spherical and hot early in its history, and has
denser rock-rich material concentrated near its center. Its average
density is about the same as Pluto, another object in the Kuiper
Belt. Phoebe likely was captured by Saturn's gravity when it somehow
got close to the giant planet.

Saturn is surrounded by a cloud of irregular moons that circle the
planet in orbits tilted from Saturn's orbit around the sun, the
so-called equatorial plane. Phoebe is the largest of these irregular
moons and also has the distinction of orbiting backward in relation
to the other moons. By comparison, Saturn's large moons appear to
have formed from gas and dust around the planet's equatorial plane
and orbit in that same plane.

"By combining Cassini data with modeling techniques previously applied
to other solar system bodies, we've been able to go back in time and
clarify why Phoebe is so different from the rest of the Saturn
system," said Jonathan Lunine, a co-author on the study and a Cassini
team member at Cornell University.

Analyses suggest that Phoebe was born within the first 3 million years
of the birth of the solar system, which occurred 4.5 billion years
ago. The moon originally may have been porous but appears to have
collapsed in on itself as it warmed up. Phoebe developed a density 40
percent higher than the average inner Saturnian moon.

Objects of Phoebe's size have long been thought to form as
potato-shaped bodies and remain that way over their lifetimes. If
such an object formed early enough in the solar system's history, it
could have harbored the kinds of radioactive material that would
produce substantial heat over a short timescale. This would warm the
interior and reshape the moon.

"From Cassini images and models, we were able to see that Phoebe
started with a nearly spherical shape, rather than an irregular shape
later smoothed into a sphere by impacts," said co-author Peter
Thomas, a Cassini team member at Cornell.

Phoebe likely stayed warm for tens of millions of years before
freezing up. The study suggests the heat also would have enabled the
moon to host liquid water at one time. This could explain the
signature of water-rich material on Phoebe's surface previously
detected by Cassini.

The new study also is consistent with the idea that several hundred
million years after Phoebe cooled, the moon drifted toward the inner
solar system in a solar-system-wide rearrangement. Phoebe was large
enough to survive this turbulence.

More than 60 moons are known to orbit Saturn, varying drastically in
shape, size, surface age and origin. Scientists using both
ground-based observatories and Cassini's cameras continue to search
for others.

The Cassini-Huygens mission is a cooperative project of NASA, the
European Space Agency and the Italian Space Agency. JPL manages the
mission for the agency's Science Mission Directorate in Washington.

CASSINI SPACECRAFT SEES NEW OBJECTS BLAZING TRAILS IN SATURN RING

FROM:  NASA
WASHINGTON -- Scientists working with images from NASA's Cassini
spacecraft have discovered strange, half-mile-sized objects punching
through one of Saturn's rings and leaving glittering trails behind
them. The results will be presented tomorrow at the European
Geosciences Union meeting in Vienna, Austria.

The penetration occurred in the outermost of Saturn's main rings,
called the F ring, which has a circumference of 550,000 miles
(881,000 kilometers). Scientists are calling the trails in the F ring
"mini-jets." Cassini scientists combed through 20,000 images and
found 500 examples of these rogues during the seven years Cassini has
been at Saturn.

"Beyond just showing us the strange beauty of the F ring, Cassini's
studies of this ring help us understand the activity that occurs when
solar systems evolve out of dusty disks that are similar to, but
obviously much grander than, the disk we see around Saturn," said
Linda Spilker, Cassini project scientist at NASA's Jet Propulsion
Laboratory (JPL) in Pasadena, Calif.

Scientists have known relatively large objects can create channels,
ripples and snowballs, or clumps of icy material, in the F ring.
However, scientists did not know what happened to these snowballs
after they were created. Some were broken up by collisions or tidal
forces in their orbit around Saturn. Scientists now have evidence
some of the smaller ones survived, and their differing orbits mean
they go on to strike through the F ring on their own.

"I think the F ring is Saturn's weirdest ring, and these latest
Cassini results go to show how the F ring is even more dynamic than
we ever thought," said Carl Murray, a Cassini imaging team member
based at Queen Mary University of London, U.K. "These findings show
us that the F ring region is like a bustling zoo of objects from a
half-mile (0.8-kilometer) in size to moons like Prometheus a hundred
miles (160.9 kilometers) in size, creating a spectacular show."

These small objects appear to collide with the F ring at gentle speeds
about 4 mph (2 meters per second). The collisions drag glittering ice
particles out of the F ring with them, leaving a trail of 20-110
miles (40-180 kilometers) long.

In some cases, the objects traveled in packs, creating mini-jets that
looked exotic, like the barb of a harpoon. Other new images show
grand views of the entire F ring and the swirls and eddies from the
different kinds of objects moving through and around it.

Saturn's rings are comprised primarily of water ice. The chunks of ice
that make up the main rings spread out 85,000 miles (140,000
kilometers) from the center of Saturn. Scientists believe the rings'
average thickness is approximately 30 feet (10 meters).

The Cassini-Huygens mission is a cooperative project of NASA, the
European Space Agency and the Italian Space Agency. JPL manages the
mission for NASA's Science Mission Directorate in Washington. The
imaging team is based at the Space Science Institute in Boulder,
Colo.

Prstence, Titan a Enceladus

Prstence, Titan a Enceladus