January 7, 2010
Ridges And Patches
image by Kevin Quin Vienna, Virginia
Kevin's large original mosaic shows many great details, but what caught my attention on this small scale overview image is the distribution of ridges and mare. Humorum is a multi-ring basin with as many as six rings identified, the most conspicuous being the 425 km diameter one (labeled with 1s) passing through the middle of Gassendi and continuing as massifs east of Mersenius and a little beyond. The Kelvin Scarp on the opposite side is part of this ring. The next ring out (2s) is visible as a rounded short ridge that abuts the north side of Mersenius, and continues as a more massive segment between de Gasparis and Palmieri. Smaller isolated hills continue it almost to Lee. The next ring out (3) is more tenuous. Starting at the top there are smaller disconnected hills that seem to define a ring. The best way to identify these rings and others is to rectify this and other phase views to achieve overhead or map views, and then overlay circles of variable diameters to maximize the match with hills. Notice the spaces between the rings - especially at the top where a rubbly texture occurs, perhaps impact ejecta. And see how often mare patches fall into the moats between rings. Such observations can reveal structure where randomness seemed to occur.
2009 Nov 29 from ~02:30 to 04:00 UT. DMK21 and C11 at f/18. 38 panels, each 2000 frames, and 250 to 1000 stacked for each in Registax, deconvolution with Astra Image, and mosaicing in Photoshop.
Rükl plate 51
Yesterday's LPOD: Hemisphere
Tomorrow's LPOD: Moon-Crossed