January 24, 2008

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A Sleepy Corner

image by Wes Higgins, Tecumseh, Oklahoma

This image proves that there are some areas on the Moon that are nearly impossibly to identify. Without the rilles at the bottom I would be lost, but two roughly parallel rilles cry out - Cauchy Rilles! And they are, with Cauchy itself between them nearly at the bottom edge. The textured area above the mare is a piece of the Moon we commonly completely overlook, with eyes fixed either on the rilles or the brilliant ray crater Proclus, here seen throughly enshadowed at top center. This area actualy has a name, Palus Somni, and as Wes' image shows its a higgely-piggely area of short ridges, bulbous hills, and no outstanding features. It is probably ejecta from the Crisium Basin, with some also from Tranquillitatis, and possibly Serenitatis and Fecunditatis. There are a number of flow-like features but their locations are hard to describe because of the paucity of lettered features. About 1/3 of the way from the bottom-right corner are two slightly curved flow-oids about 20 km long - for reference, Cauchy is 12 km wide. These are fairly wide and have both bright and shadow-casting edges. They appear to be coating the underlying rough surface. It will be fascinating to get a similar high res, low-Sun view of their source area just west of da Vinci, which is out of this view. A somewhat similar flow or ridge is just above Proclus A, the bright crater just to the right of the thick-walled and lava-floored Lyell just above the mare. If you found these odd features, try for the 4-5 km wide dome (with a dark pit) about 1/4 of the way from the top near the left side. It is on the smooth floor within a ridge-bounded feature whose origin is unknown. If the dome is real, it existence suggest the material it is on is volcanic, even though it's not dark under high Sun.

Chuck Wood

Technical Details
10-29-07, UT 9:54. 18" Reflector, Infinity 2-1m video camera, MAP 98/64, stack of 40 frames. Lat 35 North, Long 97 West, Elevation 1043 feet.

Related Links
Rükl plates 26 & 37

Yesterday's LPOD: Lamech Plateau

Tomorrow's LPOD: Sky Painting


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