Starship Asterisk*

Hello,

I just found this new image of 2001 Mars Odyssey:

PIA13786

Has anyone of you an idea of what this light material on the edge of the mountains could be?

It does look like the white stuff ends at a 'shear' line, so perhaps It's a mineral of some sort that was exposed from beneath the ground by quake activity.

Hofi wrote:Has anyone of you an idea of what this light material on the edge of the mountains could be?

Light, maybe? It's not obvious it is a material at all (that is, not a different material from the surrounds).

What the???? When i looked at the picture yesterday, the white 'stuff' was whiter and smoother with NO ridges on it and distinctly looked different than the rest of the surface. I wish I'd taken a screen shot of it, it looks so different to me today. Musta been that 1000 post thing.

I just checked again and it now looks like it did yesterday!! I must have my own private optical illusion going on.
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To make a long story very short, i printed out the mars photo and discovered that it gives me an optical illusion. I either see ridges in the white stuff, OR, i see little gullies and rather smooth tops and the white stuff is brighter. Don't know why, just is.

According to Hofi, who posted the picture, The white stuff has smooth tops and there are little gullies running down through it. There are no ridges.
As I'm posting this, I'm seeing ridges. So for those of you who are seeing ridges, your eyes(brain) is playing tricks on you, just as mine does. Too bad Asterisk does not have an optical illusion forum. This picture would get my vote!!

I'm not quite sure what the issue is Beyond. The brightest white areas are on the sunward side of ridges, with shadow on the opposite side of them. I tried downloading the image, opening it in my image software and rotating it. Usually this makes any such illusion obvious and allows me to flip from one "side" of the illusion to the other quite easily. But in this case I get ridges in all four orientations.

Rob

That's just it, Rob. The white stuff is NOT supposed to have ridges! Hofi, who posted it, says there are NO ridges in the white stuff. It has small gullies and the white stuff is rather smooth on top. Perhaps you should print it out as i did and take a look once in a while. Once it happens to you, you'll know.
When i see it with the ridges, it looks like a different picture than with the little gullies. When i see it with the gullies the white stuff is brighter and it doesn't look as though the white is caused by sunlight, but that may be an optical illusion also.To me, the white almost looks like ivory.

beyond wrote:That's just it, Rob. The white stuff is NOT supposed to have ridges! Hofi, who posted it, says there are NO ridges in the white stuff. It has small gullies and the white stuff is rather smooth on top. Perhaps you should print it out as i did and take a look once in a while. Once it happens to you, you'll know.
When i see it with the ridges, it looks like a different picture than with the little gullies. When i see it with the gullies the white stuff is brighter and it doesn't look as though the white is caused by sunlight, but that may be an optical illusion also.To me, the white almost looks like ivory.

I don't understand the issue, either. If a different image was under original consideration, there's no way to comment on it. But the image that is currently seen above, and which is on the NASA site as PIA13786, looks to me like a region of complex terrain, with the white areas indicating reflected sunlight (or possibly thermal emission, depending on the wavelength band or bands used). It doesn't look to me like the white defines a mineral distribution. And I do see ridge and gully structure in the white areas.

I'm not sure it is sun glare. HiRISE images of Coprates Chasma can be found here.

One image I found particularly interesting was:


Mesa Top Light-Toned Cap Rock in Coprates Chasma (PSP_007930_1650)

beyond wrote:That's just it, Rob. The white stuff is NOT supposed to have ridges!...

I didn't say the white stuff has ridges. I said it was on the sunward side of ridges, with shadow on the other side. As for the white stuff being flat, the ridges don't need to be steep to have this visual effect. A small slope will do, and the overall landscape can still be close to flat (as seen in the image just posted by bystander above.)

By the way, I respect your statement that you had an odd visual effect occur; I'm not trying to deny that.

Rob

Ha-Ha-Ha. Rob, i have lots of odd visual effects occur! You saw one with the christmas lights picture i did in December and if i can get to croping, there's a few more visual effects that i can post. I just wanted to point out that Hofi (the poster) sees the picture as being brighter white with little gullies, much like the white in bystanders picture, only with little gullies. When you see it with the brighter white, it stands out more, like the white plateau in bystanders picture. So here i am, in the middle. I can see the picture as Hofi sees it, brighter white with little gullies and i can also see it as having ridges and being a duller color, almost like the surrounding area. Just in doing this post i have seen it both ways. So unless someone else can see it as Hofi and i can, i suppose there is no reason for me to say anything more about it, except that Hofi doesn't see it with ridges, whereas i can. So the Poster and the commenters are seeing two different things, and i seem to be the twain where they meet, because i can see it both ways. There-fore i am going to push the keyboard slowly away and hit 'Submit' and check back once in a while to see what's up with the conversations. Ta-Ta