[X] My Assistant

[Guest_AlexBlackwell_*]

Two papers announcing new results of observations of Mars' south polar cap, Langevin et al. and Kieffer et al., are being published in the August 17, 2006, issue of Nature. See the Editor's Summary for a brief synopsis and links.

[Guest_gil nodges_*]

Hi Doug,

The streaks DO disappear at the top of the picture (whether they end suddenly, or not, is open for debate). In my mind, there are only 3 explanations for this. 1) the prevailing wind suddenly dies down, which is extremely unlikely in such a small sample of terrain 2) as more surface areas are exposed, it dilutes the visual prominence of the wind streaks, or 3) the streaks are composed of plumes of material that has been lofted into the air, and the top of the picture represents areas where the plumes have already dispersed and subsided.

http://www.msss.com/mars_images/moc/2005/0...29.S0602060.gif

I believe your point about shadows is very important, and certainly needs to be addressed, but doesn't necessarily mean this new finding is fiction. A few explanations I can think of that MAY explain the lack of shadows cast down and to the riht are:

1) plumes of dust/ice in the atmosphere creates a haze, which eliminates the shadows (like a cloudy day).

2) the illumination is not really from the upper left. I have no reason to doubt what I am being told, or the intentions/competence of the good people who are releasing the information. However, it is difficult to believe something that my own eyes tell me is not correct. For instance, the picture below says it is illuminated from the upper left, as well. Everything I see in this picture tells me otherwise.

http://www.msss.com/mars_images/moc/2005/0...30.S0800321.gif

Finally, in regards to the first picture, can someone explain the "hazy" center of the image? There appears to be a haze that is obscuring some of the streaks.

I'm not saying whether the plumes are real, or not, all I am saying is we must look at all possible explanations before writing it off.

[djellison]

2) the illumination is not really from the upper left.

It is.Fact.

If your eyes tell you otherwise, then you need to alter your perception of the image. There's stuff that's open to interpretation, and there's stuff that isn't. The angle of illumination falls in the second catagory.

As for haze - this is a polar region, and the polar regions have a lot of clouds around, it wouldn't be unusual to have some thin high cloud over this sort of area.

Doug