Mysterious 'Magic Island' appears on Saturn's moon Titan

Jun 22, 2014
Titan's methane cycle is strikingly similar to Earth’s hydrologic cycle and the only other one known to include stable bodies of surface liquids, such as this north polar sea Ligeia Mare. The Cassini mission has characterized Titan’s surface liquid inventory and Ligeia Mare is now known to have a mixed composition of methane, ethane, and dissolved nitrogen. The sea appeared quiescent throughout the 90 Kelvin north polar winter, but on July 10th, 2013 transient features were discovered. Dynamic phenomena are expected to occur with increased frequency and intensity as the 2017 northern summer solstice approaches and will afford Cassini the opportunity to begin characterizing the nature of energetic processes in these alien seas. This image has been modified for aesthetic appeal and is shown in false colour. Credit: NASA/JPL-Caltech/ASI/Cornell

Now you don't see it. Now, you do. And now you don't see it again. Astronomers have discovered a bright, mysterious geologic object – where one never existed – on Cassini mission radar images of Ligeia Mare, the second-largest sea on Saturn's moon Titan. Scientifically speaking, this spot is considered a "transient feature," but the astronomers have playfully dubbed it "Magic Island."

Reporting in the journal Nature Geoscience June 22, the scientists say this may be the first observation of dynamic, geological processes in Titan's northern hemisphere. "This discovery tells us that the liquids in Titan's northern hemisphere are not simply stagnant and unchanging, but rather that changes do occur," said Jason Hofgartner, a Cornell University graduate student in the field of planetary sciences, and the paper's lead author. "We don't know precisely what caused this 'magic island' to appear, but we'd like to study it further."

Titan, the largest of Saturn's 62 known moons, is a world of lakes and seas. The moon – smaller than our own planet – bears close resemblance to watery Earth, with wind and rain driving the creation of strikingly familiar landscapes. Under its thick, hazy nitrogen-methane atmosphere, astronomers have found mountains, dunes and lakes. But in lieu of water, liquid methane and ethane flow through riverlike channels into seas the size of Earth's Great Lakes.

To discover this geologic feature, the astronomers relied on an old technique – flipping. The Cassini spacecraft sent data on July 10, 2013, to the Jet Propulsion Laboratory at the California Institute of Technology for image processing. Within a few days, Hofgartner and his colleagues flipped between older Titan images and the newly processed pictures for any hint of change. This is a long-standing method used to discover asteroids, comets and other worlds. "With flipping, the human eye is pretty good at detecting change," said Hofgartner.

Region of the transient features before they were discovered. Transient features are not present. This image was acquired by the Cassini RADAR system on April 26th, 2007. It has been modified for aesthetic appeal and is shown in false colour. Credit: NASA/JPL-Caltech/ASI/Cornell

Prior to the July 2013 observation, that region of Ligeia Mare had been completely devoid of features, including waves.

Titan's seasons change on a longer time scale than Earth's. The moon's is transitioning from spring to summer. The astronomers think the strange feature may result from changing seasons.

In light of the changes, Hofgartner and the other authors speculate on four reasons for this phenomenon:

Transient features in Ligeia Mare, circled in red. This image was acquired by the Cassini RADAR system on July 10th, 2013. It has been modified for aesthetic appeal and is shown in false colour. Credit: NASA/JPL-Caltech/ASI/Cornell
  • Northern hemisphere winds may be kicking up and forming waves on Ligeia Mare. The radar imaging system might see the waves as a kind of "ghost" island.
  • Gases may push out from the sea floor of Ligeia Mare, rising to the surface as bubbles.
  • Sunken solids formed by a wintry freeze could become buoyant with the onset of warmer temperatures during the late Titan spring.
  • Ligeia Mare has suspended solids, which are neither sunken nor floating, but act like silt in a terrestrial delta.

Region of the transient features after they were discovered. Transient features are not present. This image was acquired by Cassini VIMS on July 26th, 2013. It has been modified for aesthetic appeal and is shown in false colour. Credit: NASA/JPL-Caltech/ASI/University of Arizona/Cornell

"Likely, several different processes – such as wind, rain and tides – might affect the methane and ethane lakes on Titan. We want to see the similarities and differences from that occur here on Earth," Hofgartner said. "Ultimately, it will help us to understand better our own liquid environments here on the Earth."

Explore further: Cassini sheds light on Titan's second largest lake, Ligeia Mare

More information: Nature Geoscience DOI: 10.1038/ngeo2190

add to favorites email to friend print save as pdf

Related Stories

Cassini nears 100th Titan flyby with a look back

Mar 06, 2014

(Phys.org) —Ten years ago, we knew Titan as a fuzzy orange ball about the size of Mercury. We knew it had a nitrogen atmosphere—the only known world with a thick nitrogen atmosphere besides Earth. But ...

Surface of Titan Sea is mirror smooth, scientists find

Mar 20, 2014

New radar measurements of an enormous sea on Titan offer insights into the weather patterns and landscape composition of the Saturnian moon. The measurements, made in 2013 by NASA's Cassini spacecraft, reveal ...

Cassini may have spotted waves in Titan's seas

Mar 19, 2014

It's no surprise that Titan's north polar region is covered with vast lakes and seas of liquid methane—these have been imaged many times by Cassini during its ten years in orbit around Saturn. What is surprising ...

Recommended for you

Bacteria manipulate salt to build shelters to hibernate

10 hours ago

For the first time, Spanish researchers have detected an unknown interaction between microorganisms and salt. When Escherichia coli cells are introduced into a droplet of salt water and is left to dry, b ...

How do we terraform Venus?

10 hours ago

It might be possible to terraform Venus some day, when our technology gets good enough. The challenges for Venus are totally different than for Mars. How will we need to fix Venus?

Biomarkers of the deep

11 hours ago

Tucked away in the southwest corner of Spain is a unique geological site that has fascinated astrobiologists for decades. The Iberian Pyrite Belt (IPB) in Spain's Río Tinto area is the largest known deposit ...

User comments : 12

Adjust slider to filter visible comments by rank

Display comments: newest first

TheGhostofOtto1923
1 / 5 (3) Jun 22, 2014
Flipping - I would hope these guys have some sort of automated way of doing this?

"Blink comparator... The blinking technique is less used than before because image differencing algorithms are often used to detect moving objects more effectively than human eyes are capable of. Or, to measure the precise position of a known object whose direction and rate of motion are known, a "track and stack" technique is used"

Etc
joemetheny3
4.7 / 5 (3) Jun 22, 2014
If you just compare the 2 pictures there are a lot of features that have expanded when the island appears.

It looks like the level of the ethane lake has just changed between the two photographs.

No big mystery.
Adam
5 / 5 (1) Jun 22, 2014
Got to wonder if it should be dubbed the "Loch Ligela Monster"?
Whydening Gyre
5 / 5 (3) Jun 22, 2014
If you just compare the 2 pictures there are a lot of features that have expanded when the island appears.

It looks like the level of the ethane lake has just changed between the two photographs.

No big mystery.

Good observation...
EKM
1 / 5 (3) Jun 22, 2014
Just had an almost Great idea, the United States has a state in located at the Northwest end of Canada called Alaska, there also s a state located out in the middle of the Pacific Ocean named Hawaii - why don't we figure out a way to have a state on Titan and call it Magic??
AntiCool
not rated yet Jun 23, 2014
Our robotic probes must surely count as out greatest scientific investment. Because of them, we live in what will surely be the golden age of planetology. I love articles like this! Thany you Cassini!
surayabay
1 / 5 (1) Jun 23, 2014
If the liquid on this moon is methane and ethane what has prevented the slightest spark or static electricity, heat from asteroid strike explosion, energy release etc, from incinerating the place?
Uncle Ira
5 / 5 (4) Jun 23, 2014
If the liquid on this moon is methane and ethane what has prevented the slightest spark or static electricity, heat from asteroid strike explosion, energy release etc, from incinerating the place?


Skippy you really don't want to get the reputation for having ol Ira having the answer to your questions. It ain't nothing to brag about no.

But to answer your question, you got to have enough of the free oxygen to get it burning. (I learn that in the engineer classes at the community college when I was studying the big diesel engines.)
SoylentGrin
5 / 5 (2) Jun 23, 2014
what has prevented [stuff] from incinerating the place?


Like Ira said, incineration or burning means "rapidly combine with oxygen". There isn't any there.

When I was a kid, I used to wonder what would happen if you caused something to spark in Jupiter's atmosphere. Would it blow up like the Hindenburg? Would we get a second sun? Then I saw pictures of the storms that rage in the atmosphere, throwing lightning strikes that would engulf Earth, and figured it would take more than a spark. =)
dramamoose
not rated yet Jun 24, 2014

When I was a kid, I used to wonder what would happen if you caused something to spark in Jupiter's atmosphere.


Man, me too. When I was much younger I believed that if I put some kleenex in the back of my plastic model of the space shuttle and set it on fire that it would go to space.
dramamoose
not rated yet Jun 24, 2014

When I was a kid, I used to wonder what would happen if you caused something to spark in Jupiter's atmosphere.


Man, me too. When I was much younger I believed that if I put some kleenex in the back of my plastic model of the space shuttle and set it on fire that it would go to space.
shawn_harmon1
not rated yet Jun 25, 2014
I think it's pretty easy to see that there are tidal forces at work on Titan, and why wouldn't there be. It's a moon orbiting a rather large planet. Just like our moon has effects on our oceans, Saturn should affect the oceans on Titan. The Island has probably always been there, we just haven't seen a pic of the area at the right time when the tides were out until now. If you look at the surrounding landscape, you'll see there is more of it exposed than there is in the picture without the island in it.