What caused a giant arrow-shaped cloud on Saturn's moon Titan?

August 16, 2011 By Stuart Wolpert, University of California Los Angeles

Titan, with arrow on left. Credit: NASA/JPL/SSI
(PhysOrg.com) -- Why does Titan, Saturn's largest moon, have what looks like an enormous white arrow about the size of Texas on its surface?

A research group led by Jonathan L. Mitchell, UCLA assistant professor of and space sciences and of atmospheric and , has answered this question by using a global circulation model of to demonstrate how planetary-scale atmospheric waves affect the moon's , leading to a "stenciling" effect that results in sharp and sometimes surprising cloud shapes.

"These atmospheric waves are somewhat like the natural, resonant vibration of a wine glass," Mitchell said. "Individual might 'ring the bell,' so to speak, and once the ringing starts, the clouds have to respond to that vibration."

The fascinating clouds, including arrow-shaped ones, that result from the atmospheric waves can cause intense — sometimes more than 20 times Titan's average seasonal rainfall — and could be essential in shaping Titan's surface by erosion.

The research was published Aug. 14 in the online edition of the journal Nature Geoscience and will be published in an upcoming print edition.

Mitchell and a colleague have described Titan's climate as "all-tropics" — the entire planet experiences the types of weather phenomena that on Earth are confined to the equatorial region.

"Our new results demonstrate the power of this analogy, not only for general features of Titan's climate but also for individual storms," Mitchell said. "In future work, we plan to extend our analysis to other Titan observations and make predictions of what clouds might be observed during the upcoming season.

"Titan's all-tropics climate gives us the opportunity to study tropical weather in a simpler setting than on Earth," he added. "Our hope is that this may help us understand Earth's weather in a changing climate."

NASA's Cassini Spacecraft has been in orbit around since late 2004 and has revolutionized our understanding of Titan, which is larger in volume than the planet Mercury and the second largest in the solar system after Jupiter's Ganymede. Titan has a thick nitrogen atmosphere and experiences rain made of natural methane gas.

"Titan is like Earth's strange sibling — the only other rocky body in the solar system that currently experiences rain," Mitchell said.

Titan is an alien world, but strangely not so different from Earth. Like Earth, the main component of its atmosphere is molecular nitrogen. Water, too, is abundant on Titan, although it is all frozen in the crust at very low temperatures. Methane is thermodynamically active in the lower atmosphere, and much like water vapor on Earth, Titan's methane forms clouds, precipitates and is resupplied from surface sources, Mitchell said. The runoff then weathers the cold surface of Titan, creating what appears to be river patterns.

Scientists think that Earth, shortly after it formed an atmosphere, had large amounts of methane and very little oxygen. Methane provided an important greenhouse warming that probably prevented Earth from staying perpetually in a completely frozen state that otherwise would have resulted from the weaker sunlight from the very young sun, Mitchell said.

"Therefore, by studying Titan's modern climate, we may gain new insights about the way the early Earth's climate was," Mitchell said.

He and his research group have developed an atmospheric model to study the climate and cloud patterns of Titan.

Co-authors on the Nature Geoscience research are Máté Ádámkovics, a project scientist with UC Berkeley's astronomy department; Rodrigo Caballero, a professor of meteorology at Sweden's Stockholm University; and Elizabeth P. Turtle, a research scientist with Johns Hopkins University's Applied Physics Laboratory.

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Aug 16, 2011
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4.5 / 5 (15) Aug 16, 2011
Its obviously a traffic sign for the new hyperspace highway. The Vogons are on the way!
not rated yet Aug 16, 2011
Perhaps all the people worried about the Sun expanding into a Red Giant needs not worry at all. Maybe they can just go live on Titan instead.
4.1 / 5 (9) Aug 16, 2011
It's a marker for the aliens to find there way to our wheat fields to try out new physics while simultaneously confounding us with pretty shapes that can't be duplicated by the local primate population.
4 / 5 (4) Aug 16, 2011

Telling us to go there.

For Hydrocar - err, Oil.
4.3 / 5 (6) Aug 16, 2011
I blame the half term holidays and kids using their spray can paint...
1.4 / 5 (7) Aug 16, 2011
What I find far more perplexing than the arrow itself is the fact that neither the journalist, the scientists involved nor even a single commenter here has mentioned the apparent inherent luminosity of these "clouds" relative to the other observable features.

People appear to be far more eager to prove the existing scientific framework than they are in investigating anomalies.

Hopefully, I need not explain that within an electrical framework for the universe, plasma-based electrical machining of a planet's surface would on occasion involve a plasma which is in the glow mode.
5 / 5 (5) Aug 16, 2011
just for the hell of it how about a close up view of what it's pointing at?
5 / 5 (3) Aug 16, 2011
It's the direction of rotation. And if you only see a line it is the start/finish line.
5 / 5 (4) Aug 16, 2011
Does that mean that the aliens are trying to sell us shoes?
3 / 5 (2) Aug 16, 2011
What the hell?

Who gave the spam ad a 5 rating?
not rated yet Aug 16, 2011
Is this the same resonance process that's responsible for the hexagonal cloud formation seen at saturns north pole?
5 / 5 (4) Aug 16, 2011
If they had only filmed the image a bit longer, I think we'd see the rest of the alien message. I'm pretty sure that proceeding the arrow are the words "Girls! Girls! Girls!"
not rated yet Aug 16, 2011
Kelvin waves. They should, according to what kind of Kelvin waves, yield some information about the topology of Titan.

5 / 5 (4) Aug 16, 2011
"This way to the Planet of the Apes! The preserve is located on the third planet in. Please, no more specimen samples.Enjoy your visit!"
3.3 / 5 (3) Aug 16, 2011
I'm guessing that it's Titan's subtle way of showing you where it's G-Spot is located.
5 / 5 (3) Aug 16, 2011
There's actually an arrow at every quarter turn - so you can Titan it just right.
5 / 5 (2) Aug 16, 2011
How come it's always "the size of Texas?" Why never any of the other million things that are apparently the same size?
not rated yet Aug 16, 2011
It's either a right turn here sign or find aliens here.

Maybe a Vogon poetry storage center? Don't think they bother with signs on a bypass ;-]
1 / 5 (7) Aug 16, 2011
Guys, science is not a competition to make the most pithy remark. Our scientific framework provides the basis for our entire worldview. The competition to make each other laugh invites the public to think of science as a spectator's sport, where critical thinking is handled by the "experts". And when the experts tell you that the world is filled with 96% dark matter and forces, our worldview is in fact hollow of any substance which we can relate to.

Neal Gabler's essay, "The Elusive Big Idea," in the New York Times provides a glimpse of where this newfound "post-idea" pithy-based community is headed, and it ain't pretty.

People need to turn their brains back on, or we're headed for Idiocracy.
4.2 / 5 (5) Aug 16, 2011
Its obviously a traffic sign for the new hyperspace highway. The Vogons are on the way!

Got my towel.
1 / 5 (2) Aug 16, 2011
Same story at your local gas station. It's a direction guide to the nearest toilet for aliens who stopped over Titan to replenish their hyrocarbon fuel stores!
1 / 5 (1) Aug 16, 2011
*Walks to the malls directory map*

-You are here.-

*Looks around a bit*

"I must have taken a wrong turn somewhere..."
1 / 5 (1) Aug 17, 2011
It looks more like a falling cat to me.
4 / 5 (4) Aug 17, 2011

"Hopefully, I need not explain that within an electrical framework for the universe, plasma-based electrical machining of a planet's surface would on occasion involve a plasma which is in the glow mode."
you are right. you dont have to, cause you have spammed this site with it enough times in the past already.
"People need to turn their brains back on, or we're headed for Idiocracy"
couldnt of said it better myself. Please do so.
1 / 5 (1) Aug 17, 2011
The small print under the arrow says "If you lived here, you'd be home already".

Strictly speaking, the dark patches are hydrocarbon "surface features", because they are not necessarily liquid at the time that the image was made.

Titan's atmosphere is completely translucent in visible spectrum. You can't see surface features. Also, the image is a false color image. The 'dark' and 'light' may not appear as such in a true color version. It is common for analysis purposes to assign arbitrary colors or shading to specific frequencies in the image so that it is possible to isolate temperature or chemical variations which you are trying to observe. You could say, for example that the oxygen frequency is green, the nitrogen is red, the liquid methane is yellow, etc. That's a bit over-simplified, but you get the general idea I'm sure.
2.3 / 5 (3) Aug 17, 2011
Neal Gabler's essay, "The Elusive Big Idea," in the New York Times provides a glimpse of where this newfound "post-idea" pithy-based community is headed, and it ain't pretty

I thought that piece was just satire. ;)
3.7 / 5 (3) Aug 17, 2011
Maybe some really big person we haven't discovered yet actually shot a really big arrow at Titan and that's what these guys think they see. It also looked like a letter "W" or maybe two "V"s. An attempt at branding? And maybe all of that methane is caused by really big cows farting. They need some environmental laws there or their climate will change and everyone will die.
5 / 5 (2) Aug 20, 2011
Hannes..like my old Scottish Grandmother said..if we didn't laugh,we would cry.
5 / 5 (3) Aug 20, 2011
smh This site is non-stop attacking and defending of science, and now, when that rare article shows up that gives us an opportunity for levity, we get reprimanded for not keeping it real. sheeesh. If there was more joking around, I wouldn't have to take stress brakes from this site. Take. It. Easy. People. As it stands, life is way too short to be taken as seriously as some do, myself included.
not rated yet Aug 21, 2011
I'd ask why my post was removed , but obviously this is a big arrow pointing to a new moderator with a small moon on their shoulder instead of a chip.

That, or my posts are made with disappearing ink.

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