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mackmckearney
2014-May-05, 01:42 PM
Why do some craters seem to come off the screen while others sink into the screen? This is making it quite difficult to distinguish boulders from craters. Any help would be greatly appreciated.

R.A.F.
2014-May-05, 02:11 PM
Why do some craters seem to come off the screen while others sink into the screen? This is making it quite difficult to distinguish boulders from craters. Any help would be greatly appreciated.

Haven't read it, but this thread (http://cosmoquest.org/forum/showthread.php?65005-Have-trouble-visually-interpreting-photos-of-craters-etc-any-suggestions-to-help) might be of help...

Trebuchet
2014-May-05, 06:00 PM
The simple answer, as I understand it, is the the human visual system is conditioned to expect light coming from above, including from the top of a picture. If light comes from the bottom of a picture, it casts a shadow on the lower (in the picture) half of the crater, where it would be cast on a bump if light was from the top. With practice, you can mentally invert the "bumps" into craters. Or just rotate the picture 180 degrees!

ETA: Here's another old thread (http://cosmoquest.org/forum/archive/index.php/t-15845.html), in which I give the same answer! And one from the BA himself (http://blogs.discovermagazine.com/badastronomy/2010/05/19/a-lunar-illusion-youll-flip-over/#.U2fSoPldUu4).

margaretannB
2014-Jun-09, 05:26 AM
I perceive it was something made from the meteorites.