NASA / JPL-Caltech / SSI

The spinning vortex of Saturn's north polar storm resembles a deep red rose in this false-color image from NASA's Cassini spacecraft. Measurements have sized the eye at a staggering 1,250 miles (2,000 kilometers) across with cloud speeds as fast as 330 miles per hour (150 meters per second). This image was taken from a distance of 261,000 miles (419,000 kilometers) on Nov. 27, 2012, with filters sensitive to near-infrared light.

The eye of a super-hurricane at Saturn's north pole looks like a peaceful red rose in a fresh bouquet of pictures from NASA's Cassini orbiter. But don't be fooled: That rosy appearance is merely due to the false colors ascribed to infrared wavelengths.

This storm's eye measures 1,250 miles (2,000 kilometers) in diameter, about 20 times wider than the average hurricane's eye on Earth. The outer clouds at the hurricane's edge are traveling at 330 mph (530 kilometers per hour), which would be off the scale on our planet. The vortex whirls inside Saturn's mysterious hexagonal cloud pattern, and it's not going anywhere.

"We did a double take when we saw this vortex, because it looks so much like a hurricane on Earth," Caltech's Andrew Ingersoll, a member of the Cassini imaging team, said in a NASA news release on Monday. "But there it is at Saturn, on a much larger scale, and it is somehow getting by on the small amounts of water vapor in Saturn's hydrogen atmosphere."

On Earth, hurricanes are fed by warm ocean water. But there are no oceans on Saturn — so what source drives this super-hurricane? Cassini's scientists want to find out, and whatever they find might add to our understanding of storm dynamics on Earth as well.

The Cassini team suspects that this storm has been active for years, but Cassini has only recently been able to watch it in visible light. When the bus-sized spacecraft arrived in 2004 to begin its $3.5 billion mission to study Saturn and its moons, the north pole was shrouded in winter darkness. Now spring is coming to the north, and Cassini has shifted to an orbit that makes it easier to see the increasingly sunlit storm.

In an email, Cassini imaging team leader Carolyn Porco of the Colorado-based Space Science Institute said the hexagon-ringed vortex is "one of the most gorgeous sights we have been privileged to see at Saturn." But such sights won't last forever: Cassini's extended mission to Saturn is due to end in 2017 with a controlled plunge into Saturn's clouds.

To keep up with the mission in its final years, check in on NASA's Cassini website as well as the online home of the Cassini imaging team, and follow @CassiniSaturn on Twitter.  

NASA / JPL-Caltech / SSI

A false-color image from Cassini highlights the storms at Saturn's north pole. The angry eye of a hurricane-like storm appears dark red, while the fast-moving hexagonal jet stream framing it is a yellowish green. Low-lying clouds circling inside the hexagonal feature appear in a muted orange color. A second, smaller vortex pops out in teal at the lower right of the image. The rings of Saturn appear in vivid blue at the top right. The colors are coded to show different near-infrared wavelengths, which are associated with different altitudes.

Slideshow: Best of Cassini

The Cassini spacecraft is sending back unprecedented imagery of Saturn, its rings and its moons. Click "Launch" to see some of the greatest hits from the Cassini mission.

Launch slideshow

Update for 8:25 p.m. ET April 30: NBC Nightly News anchor Brian Williams found these pictures as awe-inspiring as I did. Here's the video clip:

More beauties from Saturn:

• Venus sparkles in Cassini snapshot
• Seasons change, and so does Saturn
• Cosmic Log archive on the Cassini mission

Alan Boyle is NBCNews.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. To keep up NBCNews.com's stories about science and space, sign up for the Tech & Science newsletter, delivered to your email in-box every weekday. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.

Slideshow: Month in Space: April 2013

Chris Hadfield / Canadian Space Agency

Feast your eyes on an alligator-like mountain range and other curiosities seen from outer space in April 2013.

Launch slideshow

NASA / JPL-Caltech / SSI

The planet Venus sparkles as a bright point of light, seen through the rings of Saturn, in this image from NASA's Cassini orbiter. Venus is the speck just above and to the right of the image's center. The picture was captured on Nov. 10, 2012.

NASA's Cassini spacecraft has been sending us eye-filling pictures of the giant planet Saturn for almost nine years, but every so often, the camera also sees the small fry of the solar system — such as Venus, which shines in the two latest offerings from the Cassini imaging team.

One of the photos, captured last November, shows Venus as seen through Saturn's gossamer rings, from a distance of 884 million miles (1.42 billion kilometers, or 9.51 AU). The other picture highlights Venus as a "morning star," hanging just beyond Saturn's edge and next to the giant planet's G ring. Venus was 849 million miles (1.37 billion kilometers, or 9.13 AU) away when that picture was taken in January, according to the imaging team. 

From such a distance, Venus looks like nothing more than a bright speck. Which isn't surprising, considering that Earth takes on pretty much the same appearance from Saturn, even though it's slightly bigger. The mind-boggling perspectives involved in space vistas led the late astronomer Carl Sagan to call our home planet a "pale blue dot," and I guess that makes Venus a pale yellow dot.

Venus looks lovely from millions of miles away, but it's not a place you'd want to visit, Carolyn Porco, the leader of the imaging team at the Colorado-based Space Science Institute, said in an email:

"Along with Mercury, Earth, and Mars, Venus is one of the rocky 'terrestrial' planets in the solar system that orbit relatively close to the sun," she wrote. "It has an atmosphere of carbon dioxide that reaches nearly 900 degrees Fahrenheit (500 degrees Celsius), a surface pressure 100 times that of Earth's, and is covered in thick, white sulfuric acid clouds, making it very bright. Despite a thoroughly hellish environment that would melt lead, Venus is considered a twin of our planet because of their similar sizes, masses, rocky compositions and close orbits.

"Think about Venus the next time you find yourself reveling in the thriving flora, balmy breezes, and temperate climate of a lovely day on Earth, and remember: You could be somewhere else!"

NASA / JPL-Caltech / SSI

Dawn on Saturn is greeted across the vastness of interplanetary space by the morning star, Venus, in this image from Cassini. Venus appears just off the edge of the planet, in the upper part of the image, directly above the white streak of Saturn's G ring. Lower down, Saturn's E ring makes an appearance. A bright spot near the E ring is a distant star. This picture was captured on Jan. 4, at a distance of about 371,000 miles (597,000 kilometers) from Saturn.

Slideshow: Best of Cassini

The Cassini spacecraft is sending back unprecedented imagery of Saturn, its rings and its moons. Click "Launch" to see some of the greatest hits from the Cassini mission.

Launch slideshow

More about Saturn and Venus:

• Space missions deliver treats from Saturn and beyond
• Solar particles moving at incredible speed near Saturn
• Venus can take on a 'cometlike' atmosphere
• Flash interactive: Guide to the new solar system 

Slideshow: Month in Space

Alan Boyle is NBCNews.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. To keep up with Cosmic Log as well as NBCNews.com's other stories about science and space, sign up for the Tech & Science newsletter, delivered to your email in-box every weekday. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.

NASA / JPL-Caltech / SSI

Saturn's storm systems swirl in a near-infrared image captured by the Cassini orbiter's camera system on Dec. 24, from a distance of 441,028 miles (709,766 kilometers).

The storms of Saturn ripple through the frame of a black-and-white close-up captured by the Cassini orbiter on Christmas Eve and received on Earth on Wednesday.

"Close-up" is a relative term: When this picture was taken, Cassini was 441,028 miles (709,766 kilometers) away from Saturn, or almost twice the distance between Earth and the moon. Also, "black-and-white" doesn't tell the whole story: The picture was captured through the wide-angle camera's CB2 red filter, which brings out more of the variations in the cloud tops of the planet's atmosphere. For an even more dramatic illustration of the effect, compare the photos accompanying this report about Saturn's north polar vortex.

So what's black and white and red all over? This picture answers the riddle.

For more pictures from Cassini, including a top-10 photo slideshow and raw imagery from last weekend's flyby of the Saturnian moon Rhea, check out NASA's Cassini website as well as the online home base for the CICLOPS imaging team. You can also click through these additional stunners from the Cassini mission:

• Holiday treats from Saturn and beyond
• Orbiter spots an alien Nile on Titan
• Seasons change, and so does Saturn
• Slideshow: Greatest hits from Cassini 

Update for 9:50 p.m. ET: I originally wrote that the CB2 filter was an infrared filter, but NASA says it's just on the edge of the visible-light spectrum, going into the near-infrared, at a wavelength of 751 nm. Good: That makes the riddle even more apt.

Alan Boyle is NBCNews.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. To keep up with Cosmic Log as well as NBCNews.com's other stories about science and space, sign up for the Tech & Science newsletter, delivered to your email in-box every weekday. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.

NASA / JPL-Caltech /ASI

This radar image from NASA's Cassini spacecraft, acquired on Sept. 26, shows a vast river system on Saturn's moon Titan. Check out the full-size version from NASA or the European Space Agency.

NASA's Cassini orbiter has spotted a river system on the Saturnian moon Titan that's reminiscent of the River Nile — except that this river is presumably filled with liquid ethane and methane instead of water.

The Titanic Nile shows up on a grainy, black-and-white picture from Cassini's radar imager, which can look through Titan's thick, smoggy atmosphere to map the surface features beneath.

The picture was taken on Sept. 26 and released today by NASA's Jet Propulsion Laboratory and the European Space Agency. It shows a branching river valley, running more than 200 miles (320 kilometers) from its headwaters to Titan's Kraken Mare, a hydrocarbon sea that's somewhere between the Caspian Sea and the Mediterranean in size.

Just as Earth has a water-based hydrological cycle, Titan has a weather cycle that moves ethane and methane around its surface and through the atmosphere. That's due to Titan's surface temperature (averaging minus-290 degrees Fahrenheit, or -179 degrees Celsius) and atmospheric pressure (one and a half times that of Earth's atmosphere).

"Titan is the only place we've found besides Earth that has a liquid in continuous movement on its surface," Steve Wall, the radar deputy team lead, said in JPL's news release. "This picture gives us a snapshot of a world in motion. Rain falls, and rivers move that rain to lakes and seas, where evaporation starts the cycle all over again. On Earth, the liquid is water; on Titan, it's methane; but on both it affects most everything that happens."

During the eight and a half years that Cassini has been passing over Saturn and its moons, the bus-sized orbiter has mapped Titan's seas, lakes and rivers in amazing detail. The orbiter even dropped a mini-probe known as Huygens down to Titan's surface for an on-the-ground view of the terrain.

Scientists have proposed sending out another, more sophisticated probe that would parachute through the atmosphere and float on one of the moon's seas — either Kraken Mare or another huge lake called Ligeia Mare. Two proposed missions are in the works, nicknamed TiME and TALISE. So far, neither of the missions have gotten the go-ahead for launch — but who knows? Maybe this view of an alien Nile will whet our appetite for a taste of Titanic seas.

More about Titan's lakes and seas:

• Tropical lake found on Titan
• Could Titan's seas harbor life?
• Orbiter sends images of Titan's seas
• One moon's forecast: Chance of methane rain
• Titan has a soft and crusty surface

Alan Boyle is NBCNews.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. To keep up with Cosmic Log as well as NBCNews.com's other stories about science and space, sign up for the Tech & Science newsletter, delivered to your email in-box every weekday. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.

NASA / JPL-Caltech / SSI

Saturn and its rings provide a backdrop for the planet's largest moon, Titan, in a true-color picture captured by NASA's Cassini orbiter on May 6.

Saturn's shades of blue and butterscotch are changing along with the planet's seasons, as illustrated by a fresh batch of true-color photos from the bus-sized Cassini orbiter.

When Cassini arrived at Saturn, seven years ago, the planet's northern hemisphere had a tint of azure blue. Since then, Saturn has gone through an equinox and a significant shift in seasons. Summer is approaching in the north, and winter is coming to the south.

The seasonal change means ultraviolet radiation is intensifying in the north, resulting in an increasing amount of yellowish haze. Meanwhile, there's a reduction in radiation hitting the southern hemisphere, and the haze is clearing as a result. The presence of the ring shadow enhances the effect in Saturn's south.

"The reduction of haze and the consequent clearing of the atmosphere make for a bluish hue: the increased opportunity for direct scattering of sunlight by the molecules in the air makes the sky blue, as on Earth," Cassini's imaging team reports in today's advisory. "The presence of methane, which generally absorbs in the red part of the spectrum, in a now-clearer atmosphere also enhances the blue."

Although Saturn has seasons like Earth's, the fact that a Saturnian year lasts 29.5 times longer than an Earth year means that the southern hemisphere's winter solstice won't occur until May 2017. And if Cassini's mission managers have their way, the orbiter will be around to see it.

"The Cassini mission was recently given rave reviews by a panel of planetary scientists and NASA program managers for its contributions to our understanding of the solar system, a circumstance that bodes well for a well-funded continuing mission over the next five years," the imaging team's leader, Carolyn Porco of the Colorado-based Space Science Institute, reported in an email today. "Despite the fact that we can't know exactly what the next five years will bring us, we can be certain that whatever it is will be wondrous."  

Saturn's largest moon, Titan, takes center stage in one of Cassini's newly released views. The moon measures 3,200 miles (5,150 kilometers) across and is covered with its own brand of hydrocarbon-rich haze. Titan is the only moon in the solar system to have an opaque atmosphere. Cassini snapped the picture you see above from a distance of about 483,000 miles (778,000 kilometers).

Here are more pictures that show Titan's true colors:

NASA / JPL-Caltech / SSI

Saturn's rings obscure part of Titan's disk in an image from NASA's Cassini orbiter. Parts of the rings appear dark near the center of this view because of the shadow cast by the planet. This image was obtained on May 16 at a distance of about 1.9 million miles (3 million kilometers) from Titan.

NASA / JPL-Caltech / SSI

Titan's recently formed south polar vortex stands out in this natural-color view of Titan from the Cassini spacecraft. The vortex may be related to the approach of southern winter and the development of a polar "hood" of denser, high-altitude haze. This picture was acquired on July 25 at a distance of about 64,000 miles (103,000 kilometers).

NASA / JPL-Caltech / SSI

NASA's Cassini spacecraft looks toward the night side of Titan and sees sunlight scattering through the periphery of the moon's atmosphere, creating a ring of color. The picture was taken on June 6 from a distance of about 134,000 miles (216,000 kilometers).

More colors from Cassini:

• Slideshow: Cassini's greatest hits
• Saturnian storm goes wild
• Take the ultimate flight around Saturn
• Saturn floats on gossamer rings

Alan Boyle is NBCNews.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. To keep up with Cosmic Log as well as NBCNews.com's other stories about science and space, sign up for the Tech & Science newsletter, delivered to your email in-box every weekday. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.

What's hotter than Justin Bieber and Emma Stone put together? Guinness World Records says the hottest stuff made by humans is the multitrillion-degree quark-gluon plasma that was produced two years ago at the Brookhaven National Laboratory's Relativistic Heavy Ion Collider, or RHIC. The plasma, also known as big-bang soup, reached a temperature of 4 trillion degrees Celsius (7.2 trillion degrees Fahrenheit), which is 250,000 times hotter than the center of the sun.

Why so hot? RHIC's physicists were seeking to duplicate the conditions that existed just an instant after the big bang that kicked off the universe's expansion 13.7 billion years ago. At that temperature, the quarks and gluons that are almost always bound together in protons, neutrons and the like are jumping around in a free, soupy state. Studying that soup could reveal how the universe is put together at its most fundamental level.

The RHIC team created the soup by accelerating gold ions in a 2.4-mile-round magnetic ring in New York, and smashing them together at nearly the speed of light. They found that the proton-sized dollops of plasma had the characteristics of a nearly perfect liquid rather than a gas.

"There are many cool things about this ultra-hot matter,” Steven Vigdor, who leads Brookhaven’s nuclear and particle physics program, said in today's news release about the Guinness recognition. "We expected to reach these temperatures  that is, after all, why RHIC was built — but we did not at all anticipate the nearly perfect liquid behavior."

Vigdor noted that trapped atom samples also behave much like a liquid on the other end of the temperature spectrum, near absolute zero. "The unity of physics is a beautiful thing!" he said.

Like an aging celebrity, the 12-year-old RHIC is slowly being eclipsed by the new kid on the block — CERN's Large Hadron Collider on the French-Swiss border, which is in its fourth year of operation. One of the detectors at the LHC, known as ALICE ("A Large Ion Collider Experiment"), is doing similar big-bang experiments with lead ions, and has achieved temperatures higher than RHIC's. Some researchers have estimated that ALICE's soup gets as hot as 10 trillion degrees. 

"The energy density at the LHC is a factor of three higher than at RHIC," Brookhaven quotes CERN physicist Despina Hatzifotiadou as saying. "This translates to a 30 percent increase in absolute temperature compared to the value achieved by RHIC. So I would say that ALICE has the record!"

The only holdup is that ALICE's team has not yet published an official temperature measurement for its quark-gluon plasma, and as Brookhaven notes, "the Guinness team is nothing if not official." That means there's still plenty of time to raise a pint of Guinness (or your favorite alternate beverage) and drink a toast to RHIC's hotness.

More about big bangs:

• Matter melts — if it's 125,000 times hotter than the sun
• LHC opens up a fresh frontier in big-bang science
• Atom-smashing scientists want even Bigger Bangs
• Interactive: Inside the Big Bang Machine
• Special report on the Large Hadron Collider

Alan Boyle is msnbc.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.

NASA / JPL-Caltech / SSI

A plume of water ice is backlit as it spews from the south polar region of Enceladus, one of Saturn's moons. The image was taken in visible light with the Cassini spacecraft's narrow-angle camera on Feb. 20, from a distance of about 83,000 miles (134,000 kilometers).

NASA's Cassini mission has delivered a dark but dramatically backlit view of "Spaceship Enceladus": an icy moon of Saturn with geysers of water ice spewing from its south polar region, as if it were turning on its thrusters.

Enceladus isn't going anywhere, of course, but the geysers have launched a lot of speculation about what might be giving rise to the spray. Is water from a hidden ocean welling up through the cracks known as "tiger stripes"? If so, what creatures might lurk in that subsurface sea?

The picture released today by Cassini's imaging team fires up the imagination, even for team leader Carolyn Porco. "Now try to tell me Enceladus isn't the coolest, most fascinating moon there is!" she said in a Twitter update touting the view.

Really? But what about Europa, an icy moon of Jupiter that is also thought to harbor a subsurface ocean, and perhaps life. A probe to study Europa is high on NASA's list of future big-ticket missions, even though such missions are currently on hold due to budgetary constraints. (There's also some recent research suggesting that Europa's hidden ocean might be too acidic for life as we know it.)

Porco made her preference plain in a volley of tweets: "Enceladus, with the most accessible habitable zone beyond Earth, is far better for discovering anything about life than Europa."

NASA is said to be planning a concept study for an eventual Enceladus mission, although tight budgets may force a change of plan. The German Aerospace Center recently unveiled a study project known as Enceladus Explorer, or EnEx, which is looking at the possibility of putting a base station on the moon's surface and drilling down into the ice. The concept calls for a type of probe known as an IceMole to melt its way down to a water crevasse, retrieve a sample of liquid water and analyze it for the presence of microbes.

EnEx's collaborators have been testing a prototype IceMole on Switzerland's Morteratsch Glacier, and they're planning to try it out on glaciers in Alaska and Antarctica, leading up to the sampling of a subglacial lake in Antarctica in 2014. If those tests are successful, the team will propose sending IceMoles to Mars and eventually to Enceladus.

Enceladus isn't the only star of this week's Saturnian show. Fresh pictures of Saturn's second-largest moon, Rhea, were released as well. These pictures were captured over the weekend during a flyby that brought Cassini within 26,000 miles (42,000 kilometers) of the heavily cratered moon. NASA says the flyby was "relatively distant" but well-suited for global geologic mapping.

NASA / JPL-Caltech / SSI

This raw, unprocessed image of Rhea was acquired by the Cassini spacecraft on Saturday and received on Earth on Sunday. The camera was pointing toward Rhea from a distance of about 26,000 miles (41,873 kilometers).

NASA / JPL-Caltech / SSI

This raw image of Rhea was taken on Saturday from a distance of about 26,000 miles (42,096 kilometers). The pattern of lines on the right side of the image is the result of data loss during transmission.

The next big flyby is scheduled for March 27, when Cassini is due to come within 46 miles (74 kilometers) of Enceladus. That's close enough to sample those plumes of ice directly — and perhaps take one more step toward unraveling the mystery of Enceladus' hidden seas.

More about Enceladus, Rhea and Cassini:

• New images reveal Enceladus' icy secrets
• See what's hot on Enceladus
• Rhea and Titan line up in photo
• Greatest hits from Cassini

NASA / JPL-Caltech / SSI

Saturn's rings stretch in front of the moons Titan and Tethys in a Dec. 7 image captured by NASA's Cassini orbiter.

What do you get when you cross the rings and moons of Saturn? That sounds like the set-up for a joke, but for the team that processes the pictures from NASA's Cassini orbiter, the answer is totally serious: You get stunning images of the moons' interplay with the giant planet's rings.

The picture above, released today, shows Saturn's rings nearly edge-on, in front of the moons Titan (left) and Tethys (right). Cassini's narrow-angle camera captured the view on Dec. 7, 2011, as it was flying by a distance of about 1.4 million miles from icy Tethys (TEETH-iss) and 1.9 million miles from smog-covered Titan.

Last week the Cassini imaging team released another stunner snapped on the same day, showing tiny Tethys (660 miles wide) near the center of Saturn's disk, just below the ring plane.

Cassini was so close to Saturn's equator that the rings look like little more than a straight line, but you can see the delicate shadows of the rings stretching across the planet's sunlit disk into darkness. When Cassini's wide-angle camera took this picture, Tethys was about 1.1 million miles away.

Saturn, with a diameter of 74,900 miles, overwhelms Tethys in size. But the gas giant's density is such that it could float in water — that is, if there were a body of water big enough for it to float in. Does that mean Saturn could take a bath? Yes ... but it might leave a ring.

NASA / JPL-Caltech / SSI

The Saturnian moon Tethys is dwarfed by the ringed planet's disk in this Dec. 7 picture from the Cassini orbiter.

More imagery from Cassini and other space probes:

• Holiday goodies from deep space
• Saturnian storm goes wild
• Greatest hits from Cassini
• Year in Space Pictures 2011

Alan Boyle is msnbc.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter or adding the Cosmic Log Google+ page to your circles. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for other worlds.

NASA / JPL-Caltech / SSI

This infrared image from the Cassini orbiter shows the hydrocarbon lake known as Kraken Mare toward the northern edge of the disk. The dark Senkyo sand sea dominates the central area of the image.

A fresh photo from the Cassini orbiter shows the hydrocarbon-rich seas and dunes of Titan, a Saturnian moon that might be capable of sustaining life as we don't know it.

The picture, published today on the websites of NASA's Saturn mission and Cassini's imaging team, shows the huge sea known as Kraken Mare as a dark spot on the northern edge of Titan's disk. The dark Senkyo dune field is front and center. Cassini's narrow-angle camera captured the view in near-infrared wavelengths from a distance of 1.2 million miles (1.9 million kilometers) on Sept. 14.

Titan is totally shrouded in smog, but Cassini's camera filters are set up to pierce through the haze and spot details on the surface below. The cold condtions on the moon are such that hydrocarbons such as ethane and methane can exist in liquid form. This rare picture from Cassini shows the glint of sunlight off the sheen of Kraken Mare, which is larger than the Caspian Sea on Earth. (And yes, Kraken is named after the mythical sea creature. "Mare" is Latin for "sea.")

NASA / JPL

This image, obtained using Cassini's Visual and Infrared Mapping Spectrometer, shows the first observed flash of sunlight reflected off a lake on Saturn's Titan moon.

Titan's seas, lakes and rivers of hydrocarbons are among the reasons why the murky Saturnian moon ranks higher than Mars on a recently published list assessing planetary habitability. That may sound strange, considering that the typical temperature on Titan is 289 degrees below zero Fahrenheit (-178 degrees Celsius). But Dirk Schulze-Makuch, an astrobiologist at Washington State University who helped put together the list, told me that it makes sense to rank Titan as the top prospect for extraterrestrial habitability.

"If you think about it, Titan has a thick protective atmosphere like Earth's, similar to the early Earth atmosphere," he said. "It has a lot of nitrogen and methane in it, and Titan has hydrocarbon lakes, energy sources. There's a lot of possibility on Titan — if you objectively evaluate the possibility of life on Titan, I would agree."

He cautioned, however, that life on Titan may not take the form of life on Earth. Titanian life would have to thrive on methane rather than oxygen or carbon dioxide. Last year, some researchers were wound up by reports that hydrogen was flowing down through the moon's atmosphere and disappearing at the surface, and that acetylene was less abundant than expected. That could be consistent with the behavior of methane-based life forms. There are other possible explanations, however. It'll be another decade at least before another probe can go to Titan to sort out the truth.

Schulze-Makuch cautioned that comparing Titan with Mars and Earth "is a little like comparing apples and oranges."

"Current Titan seems to be more favorable to life than current Mars, but it's 'life as we don't know it,'" he said. "It would have to be different. For Mars, though, the thing is, early Mars and current Mars are very different. Early Mars was more favorable to life. Early Mars comes out better than Titan."

That's the main point of NASA's $2.5 billion Mars Science Laboratory mission, which was launched over the weekend. The mission's Curiosity rover isn't suited for detecting present-day life on the Red Planet, but it should give scientists a far better idea of what conditions on early Mars were like and whether life could have gained a foothold billions of years ago.

The real value of the Planetary Habitability Index developed by Schulze-Makuch and his colleagues would be to help scientists focus on potentially livable planets beyond our solar system. "Right now we have more than 700 exoplanets," he said. "In a few years, we'll have several thousand. You'll need to have something that you can use to prioritize. ... We have to have some way to assess what is the likelihood of life on them."

Schulze-Makuch acknowledged that the index as currently devised has lots of question marks attached to it. "One of the major points of the paper was that this classification system can always be updated, and it should be as more information becomes available," he said.

Where do you think we should focus our attention? On Titan? Mars? Ice-covered Europa? Ice-spewing Enceladus? Or on the hundreds of planets beyond the solar system? Feel free to weigh in with your comments below.

More about the search for alien life:

• Mars life? New rover may uncover clues
• Liquid water on Enceladus could support life
• Life-bearing lake possible on icy Europa
• Alien Earths: 2 billion of them are out there

Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds. 

NASA / JPL-Caltech / SSI

Saturn's northern storm marches through the planet's atmosphere in the top right of this false-color mosaic from NASA's Cassini spacecraft.

"Over the past year, a great disquiet has swept across the face of Saturn..." It sounds like the beginning of a science-fiction movie, but it's actually the latest missive from Carolyn Porco, head of the imaging team for the Cassini mission to Saturn. Today, Porco and her colleagues presented a visual chronicle of the largest Saturnian storm in more than a decade.

The storm was first noticed almost a year ago, as a spot near the line between day and night on the northern hemisphere. Since then, it's grown into a wide, bright band stretching around the entire planet.

"With a 200-day interval of intense, hissing convection, it holds the record as the longest-lasting Saturn-encircling storm ever," Porco writes. "And it has become the largest by far ever observed on the planet by an interplanetary spacecraft, giving us an unparalleled opportunity to study in great depth the subtle changes on the planet that preceded the storm's formatin and the mechanisms involved in its development."

The imaging team has bumped up the colors on a few of the images, like the one shown above, but the true-color images taken over the course of the past year tell a story that's just as dramatic.

NASA / JPL-Caltech / SSI

Images from Cassini show the evolution of a giant Saturnian storm over the course of months.

It's been 14 years and a month since Cassini was launched, and for seven and a half years it's been observing Saturn and many of its 60-plus moons. That puts Cassini right up there with the Mars rovers among NASA's most successful interplanetary missions. "And with any luck, there'll be a great deal more to come," Porco writes.

More from Cassini:

• Rounding up Saturn's moons
• Saturnian moons merge into a quintet
• A double scoop of Saturn's moons
• It's a Saturnian moonapalooza!
• Happy holidays from Saturn's moons
• Slideshow: Cassini's greatest hits

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