Titan's changing lakes |
Titan's changing lakes |
Dec 21 2009, 03:17 PM
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#151
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Founder Group: Chairman Posts: 14432 Joined: 8-February 04 Member No.: 1 |
Anyone for popcorn
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Dec 21 2009, 05:03 PM
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#152
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Member Group: Members Posts: 723 Joined: 13-June 04 Member No.: 82 |
Fight! Fight! Fight! Fight!
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Dec 22 2009, 01:30 AM
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#153
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Member Group: Members Posts: 610 Joined: 23-February 07 From: Occasionally in Columbia, MD Member No.: 1764 |
Anyone for popcorn Actually, Doug, I half-expected you to kill the thread as becoming too inflamed... Jason and I are good at what we do in part because we believe in it, are passionate about it, and, sometimes, defensive about it. Anyway, the Titan-ExtraSolarPlanets analogy is kind of interesting (I've noticed, passim, that quite a number of Exoplanet talks now show Titan, sometimes a hazy crescent to represent photochemical haze alluding to early Earth, or sometimes a surface albedo image just as a conveniently 'wierd' planetary background. I bet the Titan sunglint image gets used a lot now in exoplanet talks). Between about 1990 and late 1994, of course, lightcurves (both near-IR and radar) were all the information we had about Titan's surface. Not that the HST imaging in 1994 really brought us that much further forward - it told us there are bright bits and dark bits, but the lightcurve already told us that in a 1-d sense. In retrospect I made a scientific goof by not following to completion a toy project that I started with Albert Haldemann and Greg Black (both radar astronomers) in the late 1990s. Albert asked the question of how would the Earth look if the Arecibo dish were on Titan pointing at Earth. So I set up a model to wrap a map of terrain types on a globe with different scattering functions and generate synthetic disk-integrated radar albedo, which also included stuff like ocean glint. But it was kind of an academic question and I never got round to finishing it. If I had been smart, as soon as people started talking about exoplanet lightcurves, I could have easily adapted the code to do sun glint rather than radar and could have squeezed off a neat little paper. I think the EPOXI crowd have more or less redone all that work now. Oh well.. |
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Dec 22 2009, 11:13 AM
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#154
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Senior Member Group: Members Posts: 3516 Joined: 4-November 05 From: North Wales Member No.: 542 |
Is it safe to come out now?
For me millimeter-smooth and micron-smooth are significantly different bits of information, even if they do probably have a common explanation. That would make this a discovery in one sense and a confirmation in another. Such amazing revelations, such a wonderful time to be alive! Having real professional comment and debate on this forum is a great bonus for the rest of us. All the people who in different ways make this possible deserve our congratulations and heartfelt thanks. |
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Dec 22 2009, 06:02 PM
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#155
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Member Group: Members Posts: 131 Joined: 30-August 06 From: Moscow, Idaho Member No.: 1086 |
Is it safe to come out now? Oh, you needn't worry -- my Ralph-seeking smart bombs rarely cause collateral damage I'm still reeling from when Ralph, as a thesis committee-member, called my Ph.D. dissertation a "tour-de-force of high school geometry"! So yeah, we do this, and have for years -- thanks for putting up with it . . . - Jason |
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Dec 22 2009, 09:05 PM
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#156
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Merciless Robot Group: Admin Posts: 8783 Joined: 8-December 05 From: Los Angeles Member No.: 602 |
Well, as long as there's some smiling involved!
Productive dynamics are where you find them... -------------------- A few will take this knowledge and use this power of a dream realized as a force for change, an impetus for further discovery to make less ancient dreams real.
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Dec 22 2009, 09:39 PM
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#157
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Senior Member Group: Members Posts: 3516 Joined: 4-November 05 From: North Wales Member No.: 542 |
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Dec 23 2009, 12:04 AM
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#158
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Junior Member Group: Members Posts: 94 Joined: 22-May 08 From: Loughborough Member No.: 4121 |
I'm still reeling from when Ralph, as a thesis committee-member, called my Ph.D. dissertation a "tour-de-force of high school geometry"! Ouch! Still, I had a referee's comment on a paper way back during my PhD that simply read "this work should not be published anywhere". Rest assured we still shifted it |
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Dec 23 2009, 02:43 AM
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#159
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Member Group: Members Posts: 813 Joined: 29-December 05 From: NE Oh, USA Member No.: 627 |
Having peanuts and beer! Agree with ngunn's sentiments.,"Having real professional comment and debate on this forum is a great bonus for the rest of us." I love the discourse. Luv this forum. Craig |
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Dec 23 2009, 03:41 AM
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#160
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Member Group: Members Posts: 610 Joined: 23-February 07 From: Occasionally in Columbia, MD Member No.: 1764 |
I'm still reeling from when Ralph, as a thesis committee-member, called my Ph.D. dissertation a "tour-de-force of high school geometry"! So yeah, we do this, and have for years Well, yeah, tee hee. I mean, you did the math all nice and stuff, and used fancy words like 'extrasolar planet transit lightcurve', but it did boil down to 'star shines, planet gets in the way, see less starlight...' I dare say when all is said and done, Professor Barnes will leave his mark on a student or two at their defenses himself. |
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Dec 23 2009, 03:15 PM
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#161
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Senior Member Group: Members Posts: 1633 Joined: 5-March 05 From: Boulder, CO Member No.: 184 |
Interesting summary and to hear that the VIMS team is considering future opportunities. I wonder if we might be able to speculate on the specular reflection opportunities with a tool like Celestia? Celestia I believe supports specular reflections so one could in theory watch when they materialize using an updated map. Looks like Fridger Schrempp (one of the Celestia developers) is getting a head start on this. He is constructing a specular reflection map - simply a pixel map showing the locations of known lakes that can be used in Celestia. http://forum.celestialmatters.org/viewtopic.php?t=358 EDIT: Here is a paper on sun glint size and another on relationship to wind induced waves in Earth's oceans. I would suppose with the sun being about 3 arcmin diameter from Titan, the surface footprint (assuming a perfectly smooth surface) would be about a kilometer on the narrow direction (longitude) and a few kilometers in the wider direction (latitude). This is pretty small, so the dominant factor in spreading would be the roughness from waves or whatever. I wrote some software in my day job to calculate sun-glint locations in geostationary weather satellite images, so in theory I could hook it up with a Cassini Titan ephemeris to try and calculate sun-glint surface locations. |
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Jan 24 2010, 08:08 PM
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#162
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Member Group: Members Posts: 813 Joined: 29-December 05 From: NE Oh, USA Member No.: 627 |
Apologies if someone has already posted the Wall et al paper.
"The active shoreline of Ontario Lacus, Titan: a morphological study of the lake and its surroundings" http://www.gps.caltech.edu/~mitri/articoli/wall_2010.pdf "Abstract Of more than 400 filled lakes now identified on Titan, the first and largest reported in the southern latitudes is Ontario Lacus, which is dark in both infrared and microwave. Here we describe recent observations including synthetic aperture radar (SAR) images by Cassini’s radar instrument (λ=2 cm) and show morphological evidence for active material transport and erosion. Ontario Lacus lies in a shallow depression, with greater relief on the southwestern shore and a gently sloping, possibly wave-generated beach to the northeast. The lake has a closed internal drainage system fed by Earth-like rivers, deltas and alluvial fans. Evidence for active shoreline processes, including the wave-modified lakefront and deltaic deposition, indicates that Ontario is a dynamic feature undergoing typical terrestrial forms of littoral modification." Nice figure of Ontario on page 15. Craig |
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Jan 24 2010, 08:30 PM
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#163
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Solar System Cartographer Group: Members Posts: 10159 Joined: 5-April 05 From: Canada Member No.: 227 |
Nice! And abstract 1466 at LPSC has a similar Ontario Lacus image. Or you can visit Toronto and see the real thing.
Phil -------------------- ... because the Solar System ain't gonna map itself.
Also to be found posting similar content on https://mastodon.social/@PhilStooke Maps for download (free PD: https://upload.wikimedia.org/wikipedia/comm...Cartography.pdf NOTE: everything created by me which I post on UMSF is considered to be in the public domain (NOT CC, public domain) |
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Jan 25 2010, 02:16 AM
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#164
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Member Group: Members Posts: 813 Joined: 29-December 05 From: NE Oh, USA Member No.: 627 |
Phil....
I live about 20 miles from Lake Erie (another inland sea). . Walk the ice ramps in the winter time... I could almost be on Titan. Except the liquid phase is molten H2O, there is no smust or smurst, and usually not a hint of methane! Craig |
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Mar 1 2010, 01:15 AM
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#165
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Senior Member Group: Moderator Posts: 3233 Joined: 11-February 04 From: Tucson, AZ Member No.: 23 |
The VIMS team has published a short paper in GRL on their specular reflection observation:
Stephan, K., R. Jaumann, R. H. Brown, J. M. Soderblom, L. A. Soderblom, J. W. Barnes, C. Sotin, C. A. Griffith, R. L. Kirk, K. H. Baines, B. J. Buratti, R. N. Clark, D. M. Lytle, R. M. Nelson, and P. D. Nicholson (2010), Specular reflection on Titan: Liquids in Kraken Mare, Geophys. Res. Lett., doi:10.1029/2009GL042312, in press. -------------------- &@^^!% Jim! I'm a geologist, not a physicist!
The Gish Bar Times - A Blog all about Jupiter's Moon Io |
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