[X] My Assistant

[volcanopele]

Odd Spot on Titan Baffles Scientists
NASA/JPL/ISS/VIMS press release
http://saturn.jpl.nasa.gov/news/press-rele....cfm?newsID=576

ISS/VIMS combined image
http://ciclops.lpl.arizona.edu/view.php?id=1111

"Red" Spot on Titan
http://photojournal.jpl.nasa.gov/catalog/PIA07877

My blog posting on all this
http://volcanopele.blogspot.com/2005/05/br...t-on-titan.html

[dvandorn]

Boy -- the "smile" sure looks like a portion of a crater rim to me. Could differential solar heating of the inner rim of a crater wall cause it to heat up enough above its surroundings that other chemical processes would take place and give you a combination of topographic control of heated atmosphere and a noticeable difference in composition?

If the smile is a crater wall, the entire crater has been degraded -- the "upper" portion of the circle is not apparent, and there seems to be dark deposit "ponds" at places where the upper portion of the rim wall ought to be...

-the other Doug

[Guest_Richard Trigaux_*]

Hello all,

I am new to this forum, but Doug already heard of me recently.

This spot is impressive: what could it be?

(Note: I discuss after the info found here at the Cassini site.

-A hot spot? Wien law indicates that a black body having its maximun emission at 5µ would be at a temperature much more than 0°C, implying that the hot spot would be liquid, see boiling water... If this is true, it would be really a huge cryovolcano! And it would provoke serious disturbances in Titan's atmosphere!

-A cloud? No if it is still at the same place during several visits. I remember that there already was such bright spots near the south pole or in the south hemisphere. Its "color" would only be what is allowed to see through the atmosphere. So Titan would have a troposphere, like the Earth, explaining that its stratosphere (the visible haze) is not so still than expected.

-Snow? Methane snow of course, which would appear the same way as a cloud. Why snow in this place? Because it is a mountain-crater rim? or just because it snowed recently just on this place?

-A surface feature? If this spot is still here in this place the next fly-by, it could be only a surface feature, such as for instance a fresh water "lava" flow. But ice would be more white, the feature is not really white, as we could expect from clouds or snow. So the feature could be a special "cleaner" terrain revealed by a crater impact, and not yet covered by atmospheric hydrocarbon falls.

So it is difficult to know what it is, as of many other Titan surface features. From this the interest of some future mission...

[Guest_Richard Trigaux_*]

From the ESA page, they say that:

1) the feature is permanent, as it is observed at each fly-by, contralily to other non-permanent similar features (which may be clouds).

2) the feature will be observed by night (without sun lighting) the 2 July 2006. This will allow to know if the excess emission is from temperature (hot spot) or from reflected sunlight (cloud, snow, surface material, etc...).

3) they think the feature cannot be a mountain (eventually a snow-capped mountain) as the crust of Titan would be not solid enough to support such a mountain.