Enceladus Archives

December 23, 2013December 23, 2015 by Jason Major

Happy Holidays from Cassini!

Saturn makes a beautifully striped ornament in this natural-color image, showing its north polar hexagon and central vortex (Credit: NASA/JPL-Caltech/Space Science Institute)

Cassini couldn’t make it to the mall this year to do any Christmas shopping but that’s ok: we’re all getting something even better in our stockings than anything store-bought! To celebrate the holiday season the Cassini team has shared some truly incredible images of Saturn and some of its many moons for the world to “ooh” and “ahh” over. So stoke the fire, pour yourself a glass of egg nog, sit back and marvel at some sights from a wintry wonderland 900 million miles away…

Thanks, Cassini… these are just what I’ve always wanted! (How’d you know?)

Saturn’s southern hemisphere is growing more and more blue as winter approaches there — a coloration similar to what was once seen in the north when Cassini first arrived in 2004:

Saturn's southern hemisphere images from a million miles away (Credit: NASA/JPL-Caltech/Space Science Institute) — Saturn’s southern hemisphere images from a million miles away (Credit: NASA/JPL-Caltech/Space Science Institute)

(The small dark spot near the center right of the image above is the shadow of the shepherd moon Prometheus.)

Titan and Rhea, Saturn’s two largest moons, pose for Cassini:

Rhea (front) and Titan, images by Cassini in June 2011 (Credit: NASA/JPL-Caltech/Space Science Institute)

The two moons may look like they’re almost touching but in reality they were nearly half a million miles apart!

Titan’s northern “land of lakes” is visible in this image, captured by Cassini with a special spectral filter able to pierce through the moon’s thick haze:

Titan images by Cassini on Oct. 7, 2013 (Credit: NASA/JPL-Caltech/Space Science Institute)

The frozen, snowball-like surface of the 313-mile-wide moon Enceladus:

Enceladus: a "snowball in space" (Credit: NASA/JPL-Caltech/Space Science Institute) — Enceladus: a highly-reflective and icy “snowball in space” (Credit: NASA/JPL-Caltech/Space Science Institute)

(Even though Enceladus is most famous for its icy geysers, first observed by Cassini in 2005, in these images they are not visible due to the lighting situations.)

Seen in a different illumination angle and in filters sensitive to UV, visible, and infrared light the many fractures and folds of Enceladus’ frozen surface become apparent:

View of the trailing face of Enceladus (Credit: NASA/JPL-Caltech/Space Science Institute)

Because of Cassini’s long-duration, multi-season stay in orbit around Saturn, researchers have been able to learn more about the ringed planet and its fascinating family of moons than ever before possible. Cassini is now going into its tenth year at Saturn and with much more research planned, we can only imagine what discoveries (and images!) are yet to come in the new year(s) ahead.

“Until Cassini arrived at Saturn, we didn’t know about the hydrocarbon lakes of Titan, the active drama of Enceladus’ jets, and the intricate patterns at Saturn’s poles,” said Linda Spilker, the Cassini project scientist at NASA’s Jet Propulsion Laboratory. “Spectacular images like these highlight that Cassini has given us the gift of knowledge, which we have been so excited to share with everyone.”

Read more about the images above and see even more on the CICLOPS Imaging Team website, and see the NASA press release here.

Thanks to Carolyn Porco, Cassini Imaging Team Leader, for the heads-up on these gifs — er, gifts!

December 19, 2013March 14, 2017 by Fraser Cain

Where Did Saturn’s Rings Come From?

Dr. Kevin Grazier was a planetary scientist with the Cassini mission for over 15 years, studying Saturn and its icy rings. He was also the science advisor for Battlestar Galactica, Eureka and the movie Gravity.

Mike Brown is a professor of planetary astronomy at Caltech. He’s best known as the man who killed Pluto, thanks to his team’s discovery of Eris and other Kuiper Belt Objects.

We recently asked them about many things – here’s what they shared with us about the rings of Saturn.

Saturn’s majestic, iconic rings define the planet, but where did they come from?

Kevin Grazier: “Saturn’s rings, good question. And the answer is different depending on which ring we’re discussing.”

That’s Dr. Kevin Grazier, a planetary scientist who worked on NASA’s Cassini mission or over 15 years, studying Saturn’s rings extensively.

Mike Brown: “Saturn’s rings – the strange things about Saturn’s rings is that they shouldn’t be there, really, in the sense that they don’t last for very long. So, if they are just left over from when Saturn was formed, they’d be gone by now. They would slowly work their way into Saturn and burn up and be gone. And yet they’re there. So they are either relatively new or somehow continuously regenerated. ‘Continuously regenerated’ seems strange and ‘relatively new’ seems also kind of strange. Something broke up – a large moon broke up, or a comet broke up – something had to have happened relatively recently. And by relatively recently, that means hundreds of millions of years ago for someone like me.”

And that’s Mike Brown, professor of planetary geology at Caltech, who studies many of the icy objects in the Solar System.

Saturn and its rings, as seen from above the planet by the Cassini spacecraft. Credit: NASA/JPL/Space Science Institute. Assembled by Gordan Ugarkovic.

Saturn’s rings start just 7,000 km above the surface of the planet, and extend out to an altitude of 80,000 km. But they’re gossamer thin, just 10 km across at some points.

We’ve known about Saturn’s rings since 1610, when Galileo was the first person to turn a telescope on them. The resolution was primitive, and he thought he saw “handles” attached to Saturn, or perhaps what were big moons on either side.

In 1659, using a better telescope, the Dutch astronomer Christiaan Huygens figured out that these “handles” were actually rings. And finally in the 1670s, the Italian astronomer Giovanni Cassini was able to resolve the rings in more detail, even observed the biggest gap in the rings.

The Cassini mission, named after Giovanni, has been with Saturn for almost a decade, allowing us to view the rings in incredible detail. Determining the origin and evolution of Saturn’s rings has been one of its objectives.

Saturn's rings. Credit: NASA/JPL/Space Science Institute. — Saturn’s rings. Credit: NASA/JPL/Space Science Institute.

So far, the argument continues:

Kevin Grazier: “There’s an age-old debate about whether the rings are old or new. And that goes back and forth – it’s been going back and forth for ages and it still goes back and forth. Are they old, or have they been there a long period of time? Are they new? I don’t know what to think, to be quite honest. I’m not being wishy-washy, I just don’t know what to think anymore.”

Evidence from NASA’s Voyager spacecraft indicated that the material in Saturn’s rings was young. Perhaps a comet shattered one of Saturn’s moons within the last few hundred million years, creating the rings we see today. If that was the case case, what incredible luck that we’re here to see the rings in their current form.

But when Cassini arrived, it showed evidence that Saturn’s rings are being refreshed, which could explain why they appear so young. Perhaps they are ancient after all.

Kevin Grazier: “If Saturn’s rings are old, a moon could have gotten too close to Saturn and been pulled apart by tidal stresses. There could have been a collision of moons. It could have been a pass by a nearby object, since in the early days of planetary formation, there were many objects zooming past Saturn. Saturn probably had a halo of material in it’s early days that was loosely bound to the moon.”

Enceladus, backdropped by Saturn's rings. Credit: NASA/JPL/ Space Science Institute. — Enceladus, backdropped by Saturn’s rings. Credit: NASA/JPL/ Space Science Institute.

There is one ring that we know for certain is being refreshed…

Kevin Grazier: “The E-Ring, certainly a new ring, because the E-Ring consists of roughly micron-sized ice particles. And micron-sized ice particles don’t last in space. They sputter and sublimate – they go away in very short time periods, and we knew that. And so when we went to Saturn with Cassini, we knew to look for a source of materiel because we knew that the individual components of the E-Ring don’t last, so it has to be replenished. So the E-Ring stands alone from the established system, and the E-Ring is absolutely new.”

In 2005, scientist discovered that Saturn’s E-Ring is being constantly replenished by the moon Enceladus. Cryovolcanoes spew water ice into space from a series of fissures at its south pole.

So where did Saturn’s rings come from? We don’t know. Are the new or old? We don’t know. It just another great mystery of the Solar System.

You can follow Kevin Grazier and Mike Brown at their Google+ pages!

December 12, 2013December 23, 2015 by Jason Major

Hubble Discovers Water Plumes Erupting from Europa

UV observations from Hubble show the size of water vapor plumes coming from Europa's south pole (NASA, ESA, and M. Kornmesser)

It’s been known since 2005 that Saturn’s 300-mile-wide moon Enceladus has geysers spewing ice and dust out into orbit from deep troughs that rake across its south pole. Now, thanks to the Hubble Space Telescope (after 23 years still going strong) we know of another moon with similar jets: Europa, the ever-enigmatic ice-shelled moon of Jupiter. This makes two places in our Solar System where subsurface oceans could be getting sprayed directly into space — and within easy reach of any passing spacecraft.

(Psst, NASA… hint hint.)

The findings were announced today during the meeting of the American Geophysical Union in San Francisco.

“The discovery that water vapor is ejected near the south pole strengthens Europa’s position as the top candidate for potential habitability,” said lead author Lorenz Roth of the Southwest Research Institute (SwRI) in San Antonio, Texas. “However, we do not know yet if these plumes are connected to subsurface liquid water or not.”

The 125-mile (200-km) -high plumes were discovered with Hubble observations made in December 2012. Hubble’s Space Telescope Imaging Spectrograph (STIS) detected faint ultraviolet light from an aurora at the Europa’s south pole. Europa’s aurora is created as it plows through Jupiter’s intense magnetic field, which causes particles to reach such high speeds that they can split the water molecules in the plume when they hit them. The resulting oxygen and hydrogen ions revealed themselves to Hubble with their specific colors.

Unlike the jets on Enceladus, which contain ice and dust particles, only water has so far been identified in Europa’s plumes. (Source)

Rendering showing the location and size of water vapor plumes coming from Europa's south pole. — Rendering showing the location and size of water vapor plumes coming from Europa’s south pole.

The team suspects that the source of the water is Europa’s long-hypothesized subsurface ocean, which could contain even more water than is found across the entire surface of our planet.

“If those plumes are connected with the subsurface water ocean we are confident exists under Europa’s crust, then this means that future investigations can directly investigate the chemical makeup of Europa’s potentially habitable environment without drilling through layers of ice,” Roth said. “And that is tremendously exciting.”

One other possible source of the water vapor could be surface ice, heated through friction.

Cassini image of ice geysers on Enceladus (NASA/JPL/SSI)

In addition the Hubble team found that the intensity of Europa’s plumes, like those of Enceladus, varies with the moon’s orbital position around Jupiter. Active jets have been seen only when Europa is farthest from Jupiter. But the researchers could not detect any sign of venting when Europa is closer.

One explanation for the variability is Europa undergoes more tidal flexing as gravitational forces push and pull on the moon, opening vents at larger distances from Jupiter. The vents get narrowed or even seal off entirely when the moon is closest to Jupiter.

Still, the observation of these plumes — as well as their varying intensity — only serves to further support the existence of Europa’s ocean.

“The apparent plume variability supports a key prediction that Europa should tidally flex by a significant amount if it has a subsurface ocean,” said Kurt Retherford, also of SwRI.

(Science buzzkill alert: although exciting, further observations will be needed to confirm these findings. “This is a 4 sigma detection, so a small uncertainly that the signal is just noise in the instruments,” noted Roth.)

“If confirmed, this new observation once again shows the power of the Hubble Space Telescope to explore and opens a new chapter in our search for potentially habitable environments in our solar system.”

– John Grunsfeld, NASA’s Associate Administrator for Science

So. Who’s up for a mission to Europa now? (And unfortunately in this case, Juno doesn’t count.)

“Juno is a spinning spacecraft that will fly close to Jupiter, and won’t be studying Europa,” Kurt Retherford told Universe Today. “The team is looking hard how we can optimize, maybe looking for gases coming off Europa and look at how the plasma interacts with environment, so we really need a dedicated Europa mission.”

We couldn’t agree more.

The findings were published in the Dec. 12 online issue of Science Express.

Sources: Hubble news releases (US and ESA)

Image credits:
Graphic Credit: NASA, ESA, and L. Roth (Southwest Research Institute and University of Cologne, Germany)
Science Credit: NASA, ESA, L. Roth (Southwest Research Institute and University of Cologne, Germany), J. Saur (University of Cologne, Germany), K. Retherford (Southwest Research Institute), D. Strobel and P. Feldman (Johns Hopkins University), M. McGrath (Marshall Space Flight Center), and F. Nimmo (University of California, Santa Cruz)

December 11, 2013March 14, 2017 by Fraser Cain

Where Should We Look for Life in the Solar System?

Emily Lakdawalla is the senior editor and planetary evangelist for the Planetary Society. She’s also one of the most knowledgeable people I know about everything that’s going on in the Solar System. From Curiosity’s exploration of Mars to the search for life in the icy outer reaches of the Solar System, Emily can give you the inside scoop.

In this short interview, Emily describes where she thinks we should be looking for life in the Solar System.

Follow Emily’s blog at the Planetary Society here.
Follow her on Twitter at @elakdawalla
And Circle her on Google+
Continue reading “Where Should We Look for Life in the Solar System?”

September 24, 2013December 23, 2015 by Nancy Atkinson

Enceladus, Afterburners Still Firing

This view of Saturn's moon Enceladus and its prominent plumes was taken by the Cassini spacecraft on April 2, 2013. Credit: NASA/JPL-Caltech/Space Science Institute.

We can never get enough of seeing those intriguing jets and plumes from Saturn’s moon Enceladus, especially this great view from the Cassini spacecraft where the plumes are back-it from the Sun while the moon’s surface is lit with reflected light from Saturn. And as you can see, those jets are still firing. There are close to 100 geyser jets of varying sizes near Enceladus’s south pole spraying water vapor, icy particles, and organic compounds out into space. If you look closely, you’ll see the entire plume is as large as the moon itself.

Can we please send another spacecraft just to study this fascinating moon?

The image was taken in blue light with the Cassini spacecraft narrow-angle camera on April 2, 2013, when Cassini was about 517,000 miles (832,000 kilometers) from Enceladus.

See more details at the Cassini website.

September 17, 2013December 23, 2015 by Jason Major

A “Mini Jet” Juts from Saturn’s F Ring

A bright "mini-jet" spotted in Saturn's F ring

We all know that Saturn’s moon Enceladus has a whole arsenal of geysers jetting a constant spray of ice out into orbit (and if you didn’t know, learn about it here) but Enceladus isn’t the only place in the Saturnian system where jets can be found — there are some miniature versions hiding out in the thin F ring as well!

Watch the 50-mile-wide Prometheus dip into the F ring (CLICK TO PLAY) NASA/JPL/SSI. Animation by J. Major.

The image above, captured by the Cassini spacecraft on June 20, 2013, shows a segment of the thin, ropy F ring that encircles Saturn just beyond the A ring (visible at upper right). The bright barb near the center is what scientists call a mini jet, thought to be caused by small objects getting dragged through the ring material as a result of repeated passings by the shepherd moon Prometheus.

Coincidentally, it’s gravitational perturbations by Prometheus that help form the objects — half-mile-wide snowball-like clusters of icy ring particles — in the first place.

Unlike the dramatic jets on Enceladus, which are powered by tidal stresses that flex the moon’s crust, these mini jets are much more subtle and occur at the casual rate of 4 mph (2 meters/second)… about the speed of a brisk walk.

The reflective jets themselves can be anywhere from 25 to 112 miles (40 to 180 kilometers) long.

See more images of mini jets — also called “classic trails” — below:

Various images of mini jets captured by Cassini from 2005 to 2008.

Over 500 of these features have been imaged by Cassini since 2005. Read more about mini jets here.

(And don’t worry, Enceladus… these little jets are interesting but they have nothing on you!)

Source: Cassini Imaging Central Laboratory for OPerationS (CICLOPS)

Image credits: NASA/JPL-Caltech/SSI/QMUL.

July 31, 2013December 23, 2015 by Nancy Atkinson

Geysers on Enceladus are Powered in Part by Saturn’s Gravity

Dramatic plumes, both large and small, spray water ice out from many locations along the famed "tiger stripes" near the south pole of Saturn's moon Enceladus. Credit: NASA/JPL/SSI.

The geyser jets of Enceladus don’t shoot out in a continuous stream, but are more like an adjustable garden hose nozzle, says Cassini scientist Matt Hedman, author of a new paper about the inner workings of this fascinating tiger-striped moon. Observations from Cassini has found that the bright plume emanating from Enceladus’ south pole varies predictably. The fluctuating factor appears to be how far or close Enceladus is to its home planet, Saturn.

Scientists have hypothesized that the intensity of the jets likely varied over time, but until now had not been able to show they changed in a recognizable pattern. Hedman and colleagues were able to see the changes by examining infrared data of the plume as a whole, obtained by Cassini’s visual and infrared mapping spectrometer (VIMS), and looking at data gathered since 2004 when Cassini entered Saturn’s orbit. In 2005, the jets that form the plumes were discovered.

“The way the jets react so responsively to changing stresses on Enceladus suggests they have their origins in a large body of liquid water,” said Christophe Sotin, a co-author and Cassini team member. “Liquid water was key to the development of life on Earth, so these discoveries whet the appetite to know whether life exists everywhere water is present.”

This set of images from NASA's Cassini mission shows how the gravitational pull of Saturn affects the amount of spray coming from jets at the active moon Enceladus. Enceladus has the most spray when it is farthest away from Saturn in its orbit (inset image on the left) and the least spray when it is closest to Saturn (inset image on the right). Credit: NASA/JPL-Caltech/University of Arizona/Cornell/SSI. — This set of images from NASA’s Cassini mission shows how the gravitational pull of Saturn affects the amount of spray coming from jets at the active moon Enceladus. Enceladus has the most spray when it is farthest away from Saturn in its orbit (inset image on the left) and the least spray when it is closest to Saturn (inset image on the right). Credit:
NASA/JPL-Caltech/University of Arizona/Cornell/SSI.

The scientists say this new finding adds to evidence that a liquid water reservoir or ocean lurks under the icy surface of the moon. This is the first clear observation the bright plume emanating from Enceladus’ south pole varies predictably. The findings were published in a scientific paper in this week’s edition of Nature.

The VIMS instrument, which enables the analysis of a wide range of data including the hydrocarbon composition of the surface of another Saturnian moon, Titan, and the seismological signs of Saturn’s vibrations in its rings, collected more than 200 images of the Enceladus plume from 2005 to 2012.

These data show the plume was dimmest when the moon was at the closest point in its orbit to Saturn. The plume gradually brightened until Enceladus was at the most distant point, where it was three to four times brighter than the dimmest detection. This is comparable to moving from a dim hallway into a brightly lit office.

Adding the brightness data to previous models of how Saturn squeezes Enceladus, the scientists deduced the stronger gravitational squeeze near the planet reduces the opening of the tiger stripes and the amount of material spraying out. They think the relaxing of Saturn’s gravity farther away from planet allows the tiger stripes to be more open and for the spray to escape in larger quantities.

“Cassini’s time at Saturn has shown us how active and kaleidoscopic this planet, its rings and its moons are,” said Linda Spilker, Cassini project scientist at JPL. “We’ve come a long way from the placid-looking Saturn that Galileo first spied through his telescope. We hope to learn more about the forces at work here as a microcosm for how our Solar System formed.”

Enceladus has likely been subject to other gravitational forces over time as well. Previous studies have shown that over hundreds of millions of years, an existing gravitational interaction between Enceladus and another moon, Dione, has caused the orbit of Enceladus to grow increasingly more elongated, or eccentric.

In turn, this produced much more tidal stress in the past and scientists think that contributed to the wide-scale fracturing and friction within Enceladus’ icy crust. The friction leads to melting of internal ice and produces an ocean and eruptions of water and organics on the surface.

Source: NASA

April 30, 2013December 23, 2015 by Nancy Atkinson

An Awesome Look at Enceladus, the Jet-Powered Moon

Plumes from Enceladus' geysers are illuminated by reflected light from Saturn. Credit: NASA/JPL-Caltech, Space Science Institute.

According to planetary scientist and Cassini imaging team leader Carolyn Porco, about 98 geyser jets of all sizes near Enceladus’s south pole are spraying water vapor, icy particles, and organic compounds out into space. The spray from those geysers are evident in this new image from Cassini, showing a big, beautiful plume, illuminated by light reflected off of Saturn. Look closely to see that the plume is as large as the moon itself.

Cassini first discovered the jets of water ice particles in 2005, and since then scientists have been trying to learn more about how they behave, what they are made of and – most importantly – where they are coming from. The working theory is that Enceladus has a liquid subsurface ocean, and pressure from the rock and ice layers above combined with heat from within force the water up through surface cracks near the moon’s south pole. When this water reaches the surface it instantly freezes, sending plumes of ice particles hundreds of miles into space.

A patchwork network of frozen ridges and troughs cover the face of Enceladus. Credit: NASA/ESA, image processed by amateur astronomer Gordan Ugarkovi?. — A patchwork network of frozen ridges and troughs cover the face of Enceladus. Credit: NASA/ESA, image processed by amateur astronomer Gordan Ugarkovic.

Cassini has flown through the spray several times now, and instruments have detected that aside from water and organic material, there is salt in the icy particles. The salinity is the same as that of Earth’s oceans.

Enceladus is just 504 kilometers (313 miles) across, but it potentially could be one of the best spots in the solar system for finding life.

The top image was taken on January 18, 2013. This view looks toward the Saturn-facing side of Enceladus, and was taken when Cassini was approximately 483,000 miles (777,000 kilometers) from Enceladus. Image scale is 3 miles (5 kilometers) per pixel.

The second, face-on, color view of Enceladus was taken by the Cassini spacecraft on January 31 2011, from a distance of 81,000 km, and processed by amateur astronomer Gordan Ugarkovic.

Sources: CICLOPS, ESA

March 19, 2013December 23, 2015 by Jason Major

Enceladus’ Jets Reach All the Way to its Sea

Saturn's moon Enceladus sprays its salty sea out into space. Those plumes are rich in phosphates. (NASA/JPL/SSI/J. Major)

Thanks to the Cassini mission we’ve known about the jets of icy brine spraying from the south pole of Saturn’s moon Enceladus for about 8 years now, but this week it was revealed at the 44th Lunar and Planetary Science Conference outside Houston, Texas that Enceladus’ jets very likely reach all the way down to the sea — a salty subsurface sea of liquid water that’s thought to lie beneath nearly 10 kilometers of ice.

Enceladus’ jets were first observed by the Cassini spacecraft in 2005. The jets constantly spray fine particles of ice into space which enter orbit around Saturn, creating the hazy, diffuse E ring in which Enceladus resides.

Emanating from deep fissures nicknamed “tiger stripes” that gouge the 512-km (318-mile) -wide moon’s south pole the icy jets — and the stripes — have been repeatedly investigated by Cassini, which has discovered that not only do the ice particles contain salts and organic compounds but also that the stripes are surprisingly warm, measuring at 180 Kelvin (minus 135 degrees Fahrenheit) — over twice as warm as most other regions of the moon.

Where the jets are getting their supply of liquid water has been a question scientists have puzzled over for years. Is friction caused by tidal stresses heating the insides of the stripes, which melts the ice and shoots it upwards? Or do the fissures actually extend all the way down through Enceladus’ crust to a subsurface ocean of liquid water, and through tidal pressure pull vapor and ice up to the surface?

"Baghdad Sulcus," one of many tiger stripe fissures on Enceladus (NASA/JPL/SSI) — “Baghdad Sulcus,” one of many tiger stripe fissures on Enceladus (NASA/JPL/SSI)

Researchers are now confident that the latter is the case.

In a presentation at the Lunar and Planetary Science Conference titled “How the Jets, Heat and Tidal Stresses across the South Polar Terrain of Enceladus Are Related” (see the PDF here) Cassini scientists note that the amount of heating due to tidal stress seen along Enceladus’ tiger stripes isn’t nearly enough to cause the full spectrum of heating observed, and the “hot spots” that have been seen don’t correlate with the type of heating caused by shear friction.

Instead, the researchers believe that heat energy is being carried upwards along with the pressurized water vapor from the subsurface sea, warming the areas around individual vents as well as serving to keep their channels open.

With 98 individual jets observed so far on Enceladus’ south polar terrain and surface heating corresponding to each one, this scenario, for lack of a better term… seems legit.

What this means is that not only does a moon of Saturn have a considerable subsurface ocean of liquid water with a heat source and Earthlike salinity (and also a bit of fizz) but also that it’s spraying that ocean, that potentially habitable environment, out into local space where it can be studied relatively easily — making Enceladus a very intriguing target for future exploration.

“To touch the jets of Enceladus is to touch the most accessible salty, organic-rich, extraterrestrial body of water and, hence, habitable zone, in our solar system.”

– Cassini imaging team leader Carolyn Porco et al.

Enceladus is actively spraying its habitable zone out into space (NASA/JPL/SSI)

Research notes via C. Porco, D. DiNino, F. Nimmo, CICLOPS, Space Science Institute at Boulder, CO, and Earth and Planetary Sciences at UC Santa Cruz, CA.

Top image: color-composite of Enceladus made from raw Cassini images acquired in 2010. The moon is lit by reflected light from Saturn while the jets are backlit by the Sun.

June 25, 2012December 23, 2015 by Nancy Atkinson

Extremes in the Saturn System

It’s just one extreme to another in this image from the Cassini spacecraft. Of course, you can’t miss the ginormous Saturn. But do you see three of what appear to be eentsy, tiny moons of the ringed planet?

Tethys (660 miles, or 1,062 kilometers across) is on the right of the image, below the rings. Smaller Enceladus (313 miles, or 504 kilometers across) is on the left of the view, below the rings. Pandora (50 miles, or 81 kilometers across) is also present in this view but is barely visible. It appears as a small grey speck above the rings on the extreme left edge of the image. Pandora has been slightly brightened by the imaging team by a factor 1.2 relative to the rest of the image.

The image was taken with the Cassini spacecraft wide-angle camera on Dec. 7, 2011 using a spectral filter sensitive to wavelengths of near-infrared light centered at 752 nanometers. The view was obtained at a distance of approximately 1.3 million miles (2.1 million kilometers) from Saturn. Image scale is about 77 miles (124 kilometers) per pixel.

Image caption: Saturn and three small moons. Credit: NASA/JPL-Caltech/Space Science Institute

Source: CICLOPS