December 7, 2013

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Beautiful Features

image by George Tarsoudis, Greece

Wow! This northern extension of George's Wednesday LPOD is full of noteworthy features, especially rilles, ridges and radial ejecta. Near bottom center, south of Kies and its dome are two near tangential ridges opening up from Kies A - these are indicators of a low oblique impact. Nearby, between Kies and König, is a short straight mare ridge that is nearly unique in having a different direction than most other nearby ridges. A set of five parallel ridges between Kies and Wolff T is also unusual in looking like frozen waves. We know they aren't, that isn't how ridges form, but I don't understand what stresses caused them to form there and with that trend direction. Wolff T is such an extreme ghost crater that it might be better to call it a ruin. It is a shallowly buried impact crater with remnants of its rim protruding above surrounding lavas. The draping of the lavas over the rest of the rim suggests that the lava was original 100 m or so higher, covering the slightly elevated rim, and then the lava deflated or somehow subsided 100 m as it solidified, but we don't see high lava marks elsewhere. The most magnificent feature in this image is the fine radiating ridges of ejecta from Bullialdus. The craters rays are gone, but these low ridges, just as every other crater once had, remain to remind us that the crater is somewhat young. But the apparent coverage of the radial ridges on the northwest of Bullialdus shows that some lavas erupted after its impact formation. Finally, notice the secondary crater chain near the top right of the image. Is is nearly radial to Bullialdus A, but the rim sharpness of that crater seems poorer than the chain. I can't find any other crater that the chain is radial to; if it is somehow from Bullialdus it cuts across the crater's other ejecta.

Chuck Wood

Technical Details
Oct 28, 2013. Telescope SkyWatcher 14 inch @f/4.5, camera QHY 5L-II, filter Red, barlow 3X.

Related Links
21st Century Atlas chart 23.

Yesterday's LPOD: It's Back

Tomorrow's LPOD: Newall Jewel


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