image by Jérôme Grenier, Paris, France.
Floor-fractured craters are the most interesting ones on the Moon because of their concentration of rilles, dark halo craters and uplifted centers. While some have easily visible rilles (Posidonius and image four dark pyroclastic deposits are visible along the western edge of the floor. At least one dark spot is from a dark halo crater on a rille. A question that I don’t have a definite answer for is why do Mersenius and Cleomedes have such narrow rilles while most floor-fractured craters have broader ones? Presumably the amount of floor fracturing - and thus rille width - is related to the amount of bending from uplift of the floor. Do these two craters have less uplift than Gassendi, Posidonius and Alphonsus?
21 Nov. 2007. Orion Optics (UK) OMC 12″ + barlow 2x + Dmk31 AF03 + IR filter.
Rükl chart 51
Lunar Orbiter IV view
Yesterday's LPOD: Not from Orbit
Tomorrow's LPOD: Another Lunar Atlas?