A Titanic wink confirms otherwordly lakes

By Phil Plait | December 17, 2009 2:49 pm

A peculiar flash of light glinting from Saturn’s largest moon confirms what’s been suspected for years: liquid lakes exist on the surface of Titan!

titan_lake_glint

[Click to entitanate.]

The image above was taken on July 8, 2009 by the Cassini spacecraft. Light can reflect off the surface of liquids, producing a little sparkle or glint, called a specular reflection. Knowing that earlier images had shown what look to be lakes of liquid methane on Titan, they kept their eyes open for Cassini’s images of the moon to show such a glint. There are lots of lakes in the northern hemisphere of Titan, making the odds better it would be seen there, but it was only last year that spring sprung in Titan’s northern latitudes. That’s when it was finally possible to see sunlight plinking off of any purported standing liquid.

And that’s what we’re seeing here. They checked to make sure this wasn’t some other source of light like lightning or geologic activity, and were able to trace the position of this glint to the shores of a monstrous lake called, appropriately, Kraken Mare. It’s a sprawling 400,000 square kilometers, bigger than the Caspian sea!

titan_map

Titan’s atmosphere is thick and hazy, so visible sunlight isn’t strong enough to produce a glint. The image was taken at 5 microns, well into the infrared, where Titan’s atmosphere is essentially transparent. Cassini was about 200,000 km (120,000 miles, about half the distance of the Earth to the Moon) away from Titan when the image was taken.

It’s a cool picture! It looks a lot like images of Earth taken from space. I don’t mean the color or fuzziness — both due to Titan’s smoggy air — but just the way our brain recognizes how a flash of light like that is from liquid. We have to double check our brains, of course, since we’re easily fooled, but the confirmation of it satisfies some part of my own brain that likes to categorize things.

And it also brings home, so to speak, just how Earthlike this alien world is. It has a thick atmosphere, weather, and a hydrological cycle… except where we have water, Titan has methane. And of course it’s incredibly cold there; water would be frozen into ice literally as hard as rock. But liquid on the surface harkens to another part of our brain, the piece that asks if life could arise in such a place.

The answer is, of course, we don’t know. Not for sure. But we can’t rule it out, either.

The more we learn about Titan — and everywhere in our solar system — the more intriguing and beguiling it gets. I know that even now scientists are planning the next generation of exploratory spacecraft. I hope one of them will take a much closer, and much wetter, look at this giant satellite world.

MORE ABOUT: Cassini, lake, methane, Saturn, Titan

Comments (46)

  1. Any evidence of amino acids on Titan yet?

  2. Nick

    Entitanate? That’s a new one!

  3. Sean

    I can see the polar bear club forming a line…

  4. North pole of Titan? I do think there may be a building with some elfin architecture there… Titanian reindeer too?

  5. Jonathan

    Too bad you already created your top images of the year post. ;) FREAKING LIQUID BODIES OF… LIQUID! OMFG!

  6. Daniel J. Andrews

    test. please ignore. delete. thx

  7. Rowan

    Kraken Mare will be the name of my future band.

  8. DemetriusOfPharos

    Am I the only one who finds the phrase “not impossible” in Phil’s second to last paragraph incredibly confusing? Should that mean “it’s not possible to rule out” or “it’s impossible to rule out”?

    By the way, just shoot me for bringing this up. Its proof I’m getting old.

  9. Wes Struebing

    Neat! I AM impressed. (now if it were only WATER…)

  10. Harman Smith

    I think I’m going to name Kraken Mare the name of my new ba– BEATEN!

    It would be the craziest thing in the world… er, out of the world, if life actually existed on Titan… even if it was just microscopic life, it would be mind-blowing. Just think about it. How different would it be from life on Earth? We need to take a closer look at Titan, ASAP. We need to stop messing around and start investing more in science!

  11. Lukas

    @ #10 DemetriusOfPharos
    “it’s not impossible to rule it out”
    is the opposite of
    “it’s impossible to rule it out”
    which is the opposite of
    “it’s possible to rule it out”
    which is the opposite of what I believe Phil was trying to say.

  12. This just fires the imagination! In my mind, I can picture an orbiting station with huge tankers carrying hydro-carbons from Titan back to Earth… Although, I suppose that would not be good for Global Warming!

  13. jf

    @ #13 Lukas:

    Phil misunderestimated the comprehensibility of the syntax. ;-)

  14. Brian

    Nice snap there, NASA!

  15. Plutonium being from Pluto

    Awesome discovery. That’s one cool lake or rather sea! Lake would be “lacus” right & sea = “mare” just like our Moon? Except unlike our Lunar mare this one really is a liquid and not just an ex-liquid, ie. lava. Given this is bigger than the Capsian sea, ‘mare’ definitely fits better. ;-)

    it’s incredibly cold there; water would be frozen into ice literally as hard as rock.

    Geologically speaking, ice *is* a sedimentary rock. Sounds strange but its true, even here on Earth. ;-)

    Would love to visit Titan and see Kraken Mare close up – is it possible to swim in a spacesuit? ;-)

    Reminds me of Stephen Baxter’s Titan novel.

  16. Yoweigh

    I got hit in the face with a piece of ice fresh out of someone’s drink once and had to get stitches. Trust me, it FEELS like a rock.

  17. neurothing

    Why is it suspected the specular glint came from reflections off of a liquid and not a sheet of frozen ice?

  18. Kevin F.

    “Reminds me of Stephen Baxter’s Titan novel.”

    It was a little overlong, but still a decent novel in the end.

  19. Crudely Wrott

    It’s a cool picture! It looks a lot like images of Earth taken from space. I don’t mean the color or fuzziness — both due to Titan’s smoggy air — but just the way our brain recognizes how a flash of light like that is from liquid. We have to double check our brains, of course, since we’re easily fooled, but the confirmation of it satisfies some part of my own brain that likes to categorize things.

    That, in a nutshell, is exactly how the process of science operates, from my point of view.

    Often, the most advanced and esoteric discoveries begin when someone observes something that is vaguely familiar, something that evokes a forgotten fact or an older observation. I have always thought this was due to certain things, old things, have been so familiar for so long that, like language, they are part of us when we are born.

    Things sometimes look familiar and those who undertake tracking down the familiarity often discover hidden relationships and unobserved principles. This process is partially responsible for our being able to take this picture and have immediate insight into what we might be looking at.

    With the idea in mind and the data before us we can have a grand ol’ time trying to show that, in this case, the reflection is not caused by liquid. In the end it seems that all other causes can be safely ruled less probable than the sun reflecting off the surface of a lake. I’d like to have a camp on that shore.

    Science! It keeps me alive and makes me grin. Thanks Phil.

  20. Brian Too

    Re “… just how Earthlike this alien world is.”

    Only a scientist could say this! First of all it’s nonsensical on the face of it. An alien world is… alien. Yes I know there are different meanings of this, but it’s still alien in every sense of the word.

    Second, we’re talking about a place that is routinely about -100° C and rains hydrocarbons. I read a novel once (long time ago) where the settlers on a moon (it might have been Titan) set fires by releasing oxygen into the atmosphere and then igniting it (since hydrocarbons were everywhere and oxygen was scarce).

    At some point it hit me–settling such a place would be hard. Terribly difficult. Any indoor facility, you’d have to keep cleaning the atmosphere of hydrocarbon contamination from the outside. Otherwise you’re breathing something like methane/ethane fumes all the time.

  21. ALL THESE WORLDS BELONG TO YOU.

    EXCEPT TITAN.

    DO NOT ATTEMPT TO LAND THERE.

    OH. WAIT. WRONG PLANET.

    NEVER MIND….

  22. Procyan

    But methane is a greenhouse gas, so how is it “essentially transparent” to infra red?

  23. Jatal

    I woke this morning and stared out the thin slits of my nightpod’s window. Titan rose in the distance, its teething surface undulating in the darkness. A sudden glint off the surface reminded me of that picture you gave me before I boarded the transport. We’re heading down to Kraken Mare in the morning to take some samples. Bez and I have a bet who will find the first meth-amphibian, lol! I owe this to you and mom for always believing in me.
    – Love Emma

    p.s. I hope my kids actually write me a message like this someday. Pictures like this give me hope they actually will.

  24. Brian

    neurothing@19: Presumably because of the uniformity of the reflection. “Specular” means mirror-like, and solid substances don’t naturally form such perfectly smooth surfaces, at least not the way a liquid does in a gravitational field.

  25. @ Procyan:
    I *think* you may be confusing infrared with Ultraviolet. Emphasis on the “I think” part….not entirely sure.

    But anyway, I actually found this to be more beautiful than any of the top 10 astronomy pictures of 2009. I wish I could explain why, but I’m not entirely certain about it. Might be the whole, “beauty in simplicity” thing, coupled with what it implies. It’s also (for me) a new take on the whole “diamond ring” effect that otherwise only occurs at the end of a solar eclipse.

    Maybe because it looks exactly what might be sitting on my desk at any given moment.

    Just…..

    So pretty.

  26. !AstralProjectile

    If you go sailing there, better stick wax in your ears.

  27. ZERO

    Liquid hydrocarbons yes but not water! Ah, yet!

    When our star expands into a red giant there might be hopes for it! But very very small chances!

  28. Josh

    Phil,

    Not sure if you’ve come across this yet but I thought you’d be interested in seeing it.
    http://www.fark.com/cgi/vidplayer.pl?IDLink=4864096

  29. Erasmussimo

    I’d like to cast a jaundiced eye on the claim that “liquids enable life”. Yes, they do in the same sense that gravity enables life (you must have something to pull the pieces together). But a necessary condition is nowhere near sufficient, and the satisfaction of that condition doesn’t give cause for hope. The primary condition, the one that supersedes all the others, is the availability of negentropy, usually in the form of sunlight. The negentropy flux at the top of the atmosphere of Titan is 100 times less than that on the earth, and the opacity of its atmosphere reduces that flux much more than the earth’s atmosphere. Multiply that reduction by the reduction in chemical reaction rates due to the lower temperature, and your chances of getting life seem to me to be infinitesimal. No, we can’t rule out the possibility, but there are a many better places to look, such as the surface of the sun.

  30. Chris A.

    @Procyan (#25):
    Methane has strong absorption bands around 3 microns and 7 microns. In between those (i.e. at 5 microns, as Phil points out) it is essentially transparent.

  31. Gary Ansorge

    34. Erasmussimo

    “such as the surface of the sun.”

    This was the dominant theme in David Brins story Sun Diver. Stable, self sustaining, self replicating plasmas HAVE been observed in the laboratory, so that might be a place we should be considering, just as soon as we have developed anti-gravity, 100% reflective “force screens” and or laser refrigerators.

    GAry 7

  32. Torbjörn Larsson, OM

    What a specular sight! It is really ground for reflection.

    [He said, with a twinkle in his eye.]

    bigger than the Capsian sea

    Don’t you have to spell that with a CAPSIAN LOCK, especially if it’s bigger? ;-)

    Why is it suspected the specular glint came from reflections off of a liquid and not a sheet of frozen ice?

    It could very well be ice, Lakdawalla at the Planetary Report blog compared it with a snap shot of Earth with specular reflection from the south pole.

    But at those temperatures, IIRC ethane is a liquid and AFAIU the methane producing it part of an observable hydrological cycle – clouds, rain, even fog now observed; and that fog that can only be produced by evaporation from liquid in this case.

    it’s nonsensical on the face of it

    Not at all, Titan with it’s hydrological and atmospheric cycles, even it seems climate cycles, is the closest Earth analog in the solar system. That is all it means.

  33. Torbjörn Larsson, OM

    The primary condition, the one that supersedes all the others, is the availability of negentropy,

    Excuse me, but that is daft, or at least blatantly wrong, twice over.

    Negentropy is not a proper measure, it is entropy exported. And contrary to what creationists think, life isn’t very dependent on entropic processes at all.

    Most metabolism are steady state reversible processes, where products are “pulled” but never in equilibrium so neither entropy dependence nor increase entropy from irreversibility if they were. As IIRC Landauer told us long ago, entropy isn’t characterizing most processes away from equilibrium.

    If entropy was limiting, we couldn’t metabolize or evolve freely. In fact, Daniel Styer has an article “Entropy and Evolution” where he debunks creationists claims on the later.

    Namely (to paraphrase Pharyngula’s post paraphrasing this) if we generously assume each individual is 1000 times “more improbable” than its ancestors 100 years ago, then the number of microstates of the descendants have now reduced to 1/1000. That means the entropy change -3 x 10^-30 J/K*s per individual.

    Or that the evolution of all organisms changes entropy at a rate of 300 J/K*s. In comparison, the entropy flux from sun light is 4 x 10^14 J/K*s!

    What is a problem for organisms growth and evolution is the constraint on the other thermodynamic axes, not the entropic measure of number of available states but the energy acting on these states. Namely free energy. Early enzymes, metabolisms and organisms were likely not very efficient, and free energy constrain most reaction rates.

    In other words, without massive free energy from light perhaps no life.

    [Note: I’m not saying that entropy isn’t useful for organisms. For example, spontaneous membrane aggregation from micelles and molecules is an entropic process, no free energy required. Without membrane compartments, no life outside of the crystal surfaces it likely started on.]

  34. Torbjörn Larsson, OM

    “free energy constrain most reaction rates”

    D’oh! I meant that free energy constrain most reactions. (So constrained reaction rates is the next step, a consequence of little available light.) I guess I got on rant on that one. :-/

  35. Torbjörn Larsson, OM

    OK, now I’m confusing rates with fluxes, so it’s me who is both daft and blatantly wrong. I blame the increase of entropy of my rapidly aging brain. (Fully 60 s for each minute!) :-D

    Anyway, I believe what I wrote was correct up to that point.

  36. Asimov Fan

    @ 20. Kevin F. Says:

    “Reminds me of Stephen Baxter’s Titan novel.”
    It was a little overlong, but still a decent novel in the end.

    Decent yes, but also just so gloomy and bleak.

    BTW. Anyone know if Baxter’s idea of how to get humans to Titan with jury-rigging an assemblage of current spacecraft would actually work?

    WARNING : POTENTIAL SPOILERS FOLLOW!

    Baxter’s novel worked when they finally got to Titan but it took so long getting there and there was so much in it that was mega-grim including its main dramatis personae. Losing some of the more sympathetic characters halfway or less through made it less than a fun read too. The surreal last section set on the future Titan in the red giant Sun era was the best part of the book, IMHON, but felt very dream-like and somewhat tacked on.

    Personally, I preferred John Varley’s more rambunctious, fun-filled Titan (Futura 1979) novel with its colourful heroine Cirrocco “Rocky” Jones and her loyal partner Gaby to Baxter’s more scientifically accurate and also well written but rather depressing novel bearing the same name.

  37. The ‘Methane-ologic cycle’ phenomenon can explain this better but I am confused how human life will exists in its seas and not on its surface?

  38. richardcavessa

    neocons are estactic there is anonther body of water to polute

  39. Sara

    I don’t get this part of the article, “The answer is, of course, we don’t know. Not for sure. But we can’t rule it out, either”.

    ??????? whaaaaaaaaaaaaaaaaaaat?

    I’m to impatient. i’d like answers, though I’ll have too wait, because they dont come until a long time, and by that time, we forget about this stuff. For me, its really simple, it’s a “yes” or a “no” to a question. I never want to hear a “I dunno”, or “Maybe” and “Maybe not.”

    Which one is it? Thats my question. I like astronomy a lot, but there are so many questions i and i want anwswers.

    And it takes a long before that happens. This is only my opinion people.

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