December 30, 2020

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Ridges And Subtle Bulges

Originally published June 12, 2011


image by Jim Phillips

Some imagers must hate me. I take their images that were often carefully processed for tonal perfection and enhance them unmercifully to bring out subtle features that aren't as important as the imaging target but are interesting none-the-less. Jim's very low Sun view of the Straight Wall is an example (and I have done it to him before) where he was interested in the shadowed Wall and the rille-split dome, but I will comment on the ridges and subtle bulges. The delicate older rille that approaches the Straight Walll nearly at right angles from the right is now well documented. A similar but fainter crease or perhaps buried rille extends from Birt towards the southwest. After seeing it here I've looked back to other images and find hints of it that were previously unnoticed. On either side of this ghost rille are ghost swells or domes. To the north, just above a small impact crater, is a possible swell 4-5 times as wide as the crater. To the south of the possible rille is a much broader apparent swelling against the mare ridge that defines the western wall of Ancient Thebit, the crater that contains the Striaght Wall. The western side of this putative swelling seems to be cut by a curving gully, but it doesn't show up in the LRO QikMap higher Sun mosaic. I've commented before that there are more buried structures (indicated by mare ridges) outside Ancient Thebit than inside, but I notice that an apparent ghost crater surrounds the small impact crater Birt B west of the Birt Rille. I love LRO, but until the spacecraft accumulates entire mosaics at low illumination I will continue to make discoveries on Jim's telescopic views.

Chuck Wood

Technical Details
The dark splotch surrounding the image information at bottom left is due to my enhancement - it isn't that way on Jim's original.

Related Links
Rükl plate 54

Yesterday's LPOD: Just Another Glorious Image

Tomorrow's LPOD: Spider Webs


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