Round Thing Near South Pole Options

[antoniseb]

Here is an image which I think is from Mars Odyssey, but I'm not certain. It is from one of the orbiters. Thanks to a friend in another forum for pointing it out.

It shows a dark, very close to circular, ring near the extremities of the polar cap.

http://www.msss.com/moc_gallery/e13_e18/me...14/E1401276.jpg
http://www.msss.com/moc_gallery/e13_e18/im...4/E1401276.html

It may be that this feature has already been discussed here, if so can someone please point me to the discussion. Otherwise, I am curious to know what you think may have caused this.

[Guest_Myran_*]

Richard Trigaux said: it is impossible to freeze a wave.

I never suggested anything such either.
When water freeze its expands somewhat. On larger areas of water this creates ice ridges since the small expansion are multiplied many times over and you get a stress so large that sheats of ice piles up in long lines.
As a child I often crawled into the triagular cages that they have within, a magical kingdom with a very special light perfect for my childhood fantasies.
But back to the question at hand here, if we start with one perfectly round lake
caused by one meteor impact or volcanic heat doesnt actually matter, the pushing action of the freezing water would push against the hard shore of frozen ice that surrounds it on all sides.
Since it started out with a round shape from the very start it would tend to freeze towards the center with circles within circles.
A more important question is why it have a dark edge, im unable to answer that.

[Guest_Richard Trigaux_*]

About freezing waer waves:

I never suggested anything such either.

This is a common suggestion, which was often proposed, so I tried to dismiss it. But your own explanation about freezing lakes making geometrical paterns is interesting, and we could expect to find such things on Mars if there are somewhere frozen lakes. I think that large floods of water flowed on Mars, from volcanic origin or breaking up water tables. This water necessarily ended somewhere, where we may find such effects you describe.



About freezing waer waves:

caused by one meteor impact or volcanic heat doesnt actually matter,

Yes it matters. Meteorite impacts are common and not very interesting, while a recent volcanic activity would be. Now we think that volcanic activities on Mars started at least 2 billions years ago, eventually had a maximum, but dit not really ended today. Only eruptions are one over 10-40 million years.

[RNeuhaus]

About freezing waer waves:
Yes it matters. Meteorite impacts are common and not very interesting, while a recent volcanic activity would be. Now we think that volcanic activities on Mars started at least 2 billions years ago, eventually had a maximum, but dit not really ended today. Only eruptions are one over 10-40 million years.

Mmm...the recent news says that the most recent Mar's volcanic activities was around 1-10 millions years ago...Indeed very recent.

Rodolfo