Hi there Mick. You posted:

.I find it hard to believe that my memory, or impression, of the unaided
full moon disc (within reason) is that affected by "illusion". I will have
to compare the two next month as you describe.

The dark and light areas of the moon show a little more contrast than those of
Mars, so detail is a bit easier to see with the unaided eye. In addition,
even fine seeing variations tend to blur the detail's edges, so it becomes
even harder to see detail of the same scale as that on the moon as viewed with
the unaided eye. Try using a red filter with your telescope and the dark
markings should be somwhat easier to see. Clear skies to you.
--
David W. Knisely
Prairie Astronomy Club: http://www.prairieastronomyclub.org
Hyde Memorial Observatory: http://www.hydeobservatory.info/

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