January 9, 2007

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Sunrise on an Unflat Plain


images by Damian Peach

The right image is a normal very good view of Wargentin, the strange crater near Schickard that overflowed with lava. The image on the left, from a day earlier, shows detail on the floor that I’ve never seen. I don’t mean the higher resolution of a high SunClementine image, but the details of the wrinkle ridges and other subtle topography that are shown at Damian’s sunrise view. The ridge pattern is more complex than when seen on other images - it has five arms, all radiating from the center. If wrinkle ridges are thrust faults (sub-horizontal movement as one piece of rock slides over its neighbor) then the ridges might be expected to be concentric - as in Humorum and most basins. The strange curved shadow at the upper right of Wargentin looks like spilled ink that has run across the surface. The ridge that casts that shadow is hardly visible in the left image and not at all in the right. That is the biggest shadow from the littlest topography that I’ve seen on the Moon. Finally, notice the two tiny bumps near the shadow-casting eastern wall. These look like the form that small impact craters take under very low illumination, but the high Sun view and Clementine show that these aren’t craters - they are little mini-domes.

Chuck Wood

Technical Details:
Left: 11 April, 2006. Right: 12 April, 2006. Both: C14 @ F41. LU075M.

Related Links:
Rükl chart 70
Damian’s website

Yesterday's LPOD: A Dome on the Limb

Tomorrow's LPOD: A Lovely Anachronism


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