September 23rd:

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October 10th:

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October 15th:

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I've processed 36 frames of Titan taken over a period of three hours; numerous clouds are seen forming and dissipating

http://imgur.com/a/i5VS6

That video of cloud dynamics is great, Ian!

I'm really impressed with this work, Ian - please keep it up! It's a great window into what is going on in that complex atmosphere.

Phil

Thanks fellas! I'm endlessly fascinated by Titan, so I'll no doubt continue to cook up image products even after Cassini has plunged into Saturn (the PDS data is so much nicer to work with).

And this is a stack of ten ratioed frames:


2016-10-30 Titan STACK of TEN

A belated thank you from me too for the superb work here on the sea-and-cloudscapes, and as ever to the Cassini team for obtaining and releasing that spectacular sequence of images.

AWESOME images IAN! I can only echo the great tribute of thanks of ngunn above.

My processed version of this observation is now up!

http://photojournal.jpl.nasa.gov/catalog/PIA21051

Jaw dropping!

This image stacking works well on Titan!

Way to totally trump me, Jason! Awesome work, sir. And is that hazes and/or fog I see hovering over Ladoga Lacus?

Yes, there is fog or faint clouds moving over Ladoga Lacus over the course of the observations, as well as in Trold Sinus in eastern Kraken Mare and moving over parts of Punga Mare later in the observation.

Is there a published map showing the names of bays and headlands in Titan's lakes and seas? If so I've missed it so far.

One thing that strikes me when I see these images, both in Ian R's stack and in Jason's superb animation, is that Ligeia Mare as a whole appears more hazy than equivalent parts of Kraken Mare at the same distance from the terminator. I don't know if that's a clue to something on Titan, an imaging thing, or just my eyes.

There is indeed such a map, courtesy of the USGS: http://planetarynames.wr.usgs.gov/images/t...rthpole_new.pdf

A full set of maps can be found here: http://planetarynames.wr.usgs.gov/Page/TITAN/target

Thanks for the links. I have been examining the most recent lake images from November 14, some of which such as this one http://saturnraw.jpl.nasa.gov/multimedia/i...6/N00272121.jpg were taken though a polarising filter. I look forward to seeing how these look when processed.

Here's a mosaic of Titan taken during the T-99 flyby. We've got a good view of Ligeia and Punga Mare, and Kraken Mare stretches away onto the night side. We've also got good views of Dilmun, Shangri-La (bottom left) and Menvra Crater (bottom right).


Titan - Cassini by Justin Cowart, on Flickr

This two-frame mosaic from December 20th appears to show a large wisp of cloud in the vicinity of the 'kissing lakes', aka Abaya Lacus:

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I think this is probably the best view of Kraken Mare to date.

Agreed, that's a superb view. The channel connecting Jingpo Lacus to Kraken Mare is particularly striking. Also the view of the 'toe of Italy' area, not well imaged by SAR, is pretty good. It could be a separate lake linked to Kraken by a similar channel.

I think there's a lot of subtle detail here that might be hidden from the eye.

I took the "summer clouds animation" (PIA21051: Watching Summer Clouds on Titan) and constructed a rough median frame by computing the pixelwise medians from the first, middle, and last frames. Then, I created a new animation which subtracts the median from each of the frames in the original work by Jason Perry. I think this makes subtle polar clouds (fog banks?) much more obvious: I count at least nine at one point. This also makes the rotation of the winds over a large area around the pole quite evident.

In order to post here, I needed to shrink the animation 4x… I think the key details are still obvious.

Very neat trick, J. I wish I had thought of that!

Conversely, stacking the frames brings out subtle details in the shorelines of the lakes and within the bright evaporite:

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Processing my own astrophotography falls, usually, into one of two modes: Deep sky objects, with incredible detail that is usually very subtle, and planetary objects, where the effects of the Earth's atmosphere is the major obstacle. In my version, Ian, and yours, we basically tackled this data set in those two ways. I used the median-subtraction to bring out faint details, and you used image stacking to compensate for the blurring effects of the atmosphere (in this case, Titan's).

This is basically a 3-D dataset, so there are many ways to rework it. Perhaps we've barely scratched the surface.

This beautiful image seems to cover a few areas that, to the best of my knowledge, have NOT been covered by radar swaths.

I see several sizeable lakes in these areas. Have they been named?

P

Another thing I've noticed in Ian's stacked image is the suggestion of a large circular feature, similar in size to Menrva and to the northeast of it. Comparing just by eye with the Titan map on Ciclops I estimate its position as very approximately LAT+45 LON 70. The circle itself is brightish and its interior shows stronger light and dark mottling than surrounding areas at the same latitude.

EDIT: Here is a crop of the feature I'm referring to -

Thanks for the addition of the close-up, ngunn. That is an intriguing feature. It seems like some sort of combination of volcanic and lake formation might be involved.

I wonder if the ‘channel’ going from Jingpo to Kraken is more the result of the lower resolution of the ISS image. We have good views of the area from the T 25 SAR and a very nice denoised view of the beginning of the ‘channel’ from Antoine Lucas’ version of Jingpo Lacus shown in Photojournal here: http://photojournal.jpl.nasa.gov/catalog/PIA19053 (BTW the caption for the image contains an error stating …”The three leftmost image pairs show bays and spits of land in Ligea Mare, one of Titan's large hydrocarbon seas. The rightmost pair shows a valley network along Jingpo Lacus, one of Titan's larger northern lakes.”… I’d suggest this should read: the two left most image pairs show bays and spits of land in Ligeia Mare, the next pair are of Jingpo Lacus and the rightmost pair show a valley network along Kraken.
Anyway the figure below overlays the T-25 SAR on IAN R’s processed mosaic from UMSF (sharpened and enhanced) and identifies seas, islands and more obvious channels.
Changes may have occurred since the T-25 SAR to ‘dampen’ the broad area making it appear as a channel, but a continuous channel … it appears not likely.
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There is a big difference between what the RADAR sees and the near IR images. I'm not sure which is the best guide to the topography or the drainage.

Refering to the circular feature: maybe impact should be considered too?

This feature has intrigued me for some time, ever since I spied it on a medium range shot from 2013:

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Nicknaming it the 'Bullseye', I spotted it again on the VIMS mosaic taken during the T-114 flyby; this is a crop of an undistorted version of PIA20016:

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Finally, here is our region of interest with the topographic map (courtesy of Ralph Lorenz, et al) lain over the ISS basemap PIA20713:

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It would appear that the 'Bullseye' is possibly a depression, perhaps even an ancient impact crater that has degraded over time. It may also be analogous to Hotei Regio, which is suspected to be a dry lake bed, harking back to seasonal conditions that favored temperate latitudes. Who knows?

With the new year comes changes on Titan: just look at the size of the cloud bands girding the upper latitudes!

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Cloud formation can be a sort of binary switch that makes visible the variations in relative humidity that are otherwise invisible.

One thing that can come out of this beautiful and mesmerizing data set is an understanding of Titan weather, using this sparse "boolean" data to interpolate/extrapolate to a wider range of times, places, conditions, etc.

In the animation I made showing the polar clouds, it would be particularly interesting to identify the times and places where clouds/fog began. It seems like perhaps a weather front is moving over lakes, causing clouds to initiate when it crosses over them. But maybe I'm primed to expect this because I used to live near and downwind of the Great Lakes on Earth.

You're quite right - even austere datasets such as we have here can be interpreted in a probabilistic way, using Bayesian reasoning / Monte Carlo methods
- the same is true of the Boolean question of 'are there waves on the sea surface on Titan (you can have calm days during the windy season and vice versa,
so perfect/accurate measurement is perhaps less important than frequent measurement)
Another example - not related to Titan - is whether rocks moved or not
https://www.lpl.arizona.edu/~rlorenz/climat...e_racetrack.pdf

animation of clouds

https://twitter.com/kevinmgill/status/815718720014196736

More superb views of lakes and clouds today: https://saturnraw.jpl.nasa.gov/multimedia/i...8/N00277002.jpg

Juramike (Mike Malaska) has a new article in Icarus on the possibility of Nitrogen bubbles affecting large patches of the N polar seas as seasonal changes occur. A great image of the N polar region and a summary of the article are found on the Cassini website https://saturn.jpl.nasa.gov/news/3008/exper...-with-nitrogen/

2017-03-20 Titan — A Double Take


2017-03-21 — Cassini Snaps Zero-Phase Titan

The features that appeared then to disappeared in liquid on Titan have indeed turned out to be foamy bubbles.
This finding is described in a paper in Nature and a popularized treat on the subject is found in Universe today.

Much of this work was done by UMSF moderator Juramike, who is quoted extensively in the Universe Today article.

This fizzy seas result is one of the most science-fiction-like things I've read in planetary science. It's like something out of a comic book. Congratulations, Mike.

No they have not. The study (to which I also contributed) showed that nitrogen bubbles could be formed in certain circumstances. Such bubbles
could account for some transient phenomena observed on Titan's seas (aka 'the magic island' observed in radar) but they
cannot account for all the transient features observed (notably by VIMS, which only sees the top fraction of a millimeter of
material).

A more parsimonious theory is that surface roughness (either locally wind-driven, i.e. 'catspaw', or nonlocally - i.e. wind-driven
currents) explains all the observed transients.

Bubbles are still fun to think about, though.

Yeah. A funny thing happened on the way to the Universe Today article....

About a month ago we had a press release that presented our Icarus paper on experiments to figure how much nitrogen goes into lake fluids. Lotsa fun implications. Lakes "breathing" in and out, gas release from liquid mixing, cool stuff (!). And we stated pretty much "Oh yeah, and bubbles might possibly could be an explanation for observations of Magic Islands in Titan seas." I mean, sure, it's still on the list of possible suspects.

A month later, another paper comes out in Nature Astronomy that describes model calculations (not using our new lab data, I might add) that had a press release saying that the problem was solved.

And somehow in a funky twist, the Universe Today article combined the Nature Astronomy article's press release first paragraphs with the last paragraphs of our earlier press release.

So basically, we got an extra bonus 15 minutes of fame riding on the back of a later paper that came to some of the same conclusions that we'd already published earlier.

I'm really not quite too sure what to make of all this....

But as for the observed Magic Islands in the lakes, I agree with Ralph that wind is a good (and leading) suspect for Magic Islands. But the properties of Titan lakes definitely causes some funkiness. (As in, no freezing of methane on Titan - but that's not a new discovery, our lab experiments just help with the "why".)

I have a question about the way patches of bubbles might produce RADAR reflections. Please excuse me if the answer is already in one of the papers: I don't have access. Are we talking about bubbles distributed through the body of the liquid or a raft of some sort of scum accumulating on the surface?

Thanks Ralph and Mike for your courageous experimental study about the bubble phenomenon. Risky I guess with all these volatile hydrocarbons...
In Ligeia Mare, I note that the coastline near the "Magic Island" is particularly irregular with numerous peninsulas or bays.
I can imagine strong erosional processes in that area as well as potential disturbances in streams.

These are quite distinct hypotheses. Floating material (e.g. pumice rafts, or some sort of bubble foam) could explain both radar and near-IR brightness, as could surface roughness from wind or currents.

A bubble plume, with voids in the methane column, could give radar backscatter, but not near-IR.

A bubble plume would be expected to be anchored to the seafloor somehow ; floating material would be pushed around a lot by wind, so the magic island's recurrence at one spot might argue somewhat against it, although some sort of pumice analog continuously/episodically released from a seafloor volcano would have some preference for location, I guess.

No, a bubble plume due to compositional mixing would not be anchored to the lake floor. It would be present anywhere there was a lower layer of ethane-richer fluid overlain by methane richer-fluid. It could be anywhere. And if there was a "bubble event" it could migrate around as the different portions of the lake hit compositional equilibrium at different times. It'd be really fun and exciting to watch.

There could, however, be places more prone to compositional mixing. Places where local winds are more prone to stir up the lakes fluids, cause mixing, and then generate a bubble-splosion. This could explain Magic Islands reappearing at same location (after a recharge of compositional disequilibrium.)

(Please note that Occam is starting to have a 5-o'clock shadow at this point....)

Thanks for the informative replies.



Do we have any near-IR evidence either way for the original 'magic island'? If so I missed it.



So it seems to me we have two separate questions to answer regarding any bubble-related explanation for the transient features. What mechanism generates the bubbles, and in which way are they rendered visible?

Mike, I wonder if you have any ideas on surfactant materials that might plausibly be present in Titan's seas? Perhaps this is another area where experimentation could prove fruitful. Can you produce a long-lasting foam under Titan conditions?

I find myself wondering whether gravels entrained by a dense river would end up floating on top of a less-dense sea.

LOL! Quite. Note that I did say 'expected' to be anchored..... as you say, anything is "possible"

Two ways you can make bubbles.
1) Heat up Titan liquids. Solubility of nitrogen in methane really drops off on heating.

2) Compositional mixing. Mix a liquid containing lotsa methane/nitrogen with liquid containing ethane (which doesn't like nitrogen so much). The excess will come out.


As for surfactants, methane (and ethane but less so) is a lousy solvent. So any surfactants that could dissolve to an appreciable and useful extent is a very short list. In our experiments we get a huge amount of bubbles generated. So all our calculations were assuming instant N2 release and bubbles and we didn't worry about long-lasting foams.