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Fraser
2008-Nov-25, 05:50 PM
With all the different spacecraft orbiting and roving on the Red Planet, we're finding that Mars is a wonderfully diverse and dynamic planet, with some unusual landforms. Take craters, for instance, and especially a few images of craters from the Mars Reconnaissance Orbiter's HiRISE camera. The image above shows a small [...]

More... (http://www.universetoday.com/2008/11/25/crazy-mars-craters/)

dhd40
2008-Nov-25, 08:35 PM
With all the different spacecraft orbiting and roving on the Red Planet, we're finding that Mars is a wonderfully diverse and dynamic planet, with some unusual landforms. Take craters, for instance, and especially a few images of craters from the Mars Reconnaissance Orbiter's HiRISE camera. The image above shows a small [...]

More... (http://www.universetoday.com/2008/11/25/crazy-mars-craters/)

First question: Is the black circle seen in the first picture of your link "real", or is it photoshopped?
Second Question: The text below the second picture talks about a mound. I donīt see any mound there, just a pit. Are my eyes cheating me?

JonClarke
2008-Nov-25, 08:55 PM
First question: Is the black circle seen in the first picture of your link "real", or is it photoshopped?

Yes. It is the frost-free rim of the crater.


Second Question: The text below the second picture talks about a mound. I donīt see any mound there, just a pit. Are my eyes cheating me?

Yes. It is a common illusion. Try rotating the image through 180 degrees and it should look like a pit.

Jon

dhd40
2008-Nov-26, 01:42 PM
Yes. It is a common illusion. Try rotating the image through 180 degrees and it should look like a pit.

Jon

I have done just this ... and only then I saw a mound. I actually mostly do this rotating because Iīm aware of the "illusion"