May 16, 2008

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Unexpected Obliquity

image by Jérôme Grenier

Are LPOD images ever too big? I tried reducing Jérôme's mosaic, but its impressiveness disappeared, so it is here in full glory. This is one of the Moon's backwater areas, often overlooked in the rush to image the old warhorses yet again. All of the larger craters here on the northeastern side of Mare Nectaris are old and degraded by subsequent impacts and lava flooding. Some are crossed by rilles, by I wouldn't call that a degradation - its an interest and challenge enhancement for observers. Gutenberg and Goclenius at upper left are cut by linear rilles that don't quite look concentric to either the Nectaris or Fecunditatis basins. There are other wall-hugging and floor-crossing rilles in Goclenius, marking it as a floor-fractured crater. It is also elliptical in outline; the left third is a smaller crater, with its own central peak. The main central peak is actually a ridge, off-center toward the west and aligned the same way. This may have been a simultaneous impact of two projectiles or an odd oblique impact. Is it a less extreme version of Schiller? The off-center mountainous ring within Gutenberg is a later impact crater, but the domed and fractured hill is peculiar. Gutenberg overlaps a an older crater, Gutenberg C to its south; this image suggest that debris from C tumbled down onto the floor of Gutenberg. Jérôme's mosaic deserves a chapter rather than a few hundred words - the concentric crater on the right side and pyroclastic deposit at extreme left warrant pointing out, but I will only add one more, perhaps new, discovery. The 17 km wide simple crater Bellot has rays, but not on the Fecunditatis side - it is another oblique impact crater.

Chuck Wood

Technical Details
11 may 2008. Orion Optics (UK) OMC 12" + barlow 2x + red filter + Dmk31AF03 camera.

Related Links
Rükl plates 48 & 59
Jérôme's website

Yesterday's LPOD: Unfamiliar Territory

Tomorrow's LPOD: Where Have All the Landers Gone?


(1) The land mass that seems to flow from the southern wall of Gutenberg is interesting. The southern crater wall and area beyond it look like they have been eroded somehow, as if something flowed out of the crater. Is the area south of Gutenberg a plateau? It looks like it might have a higher elevation than Gutenberg. Is it part of the Pyrenees?


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