December 26, 2011
Boxing Day Present
image from LROC Featured Image, [NASA/GSFC/Arizona State University]
Thanks to Mark Robinson, leader of the LRO Camera team, for posting this dramatic image on Christmas Day. This oblique view of the western floor and wall of Aristarchus was obtained by pointing the Narrow Angle Camera obliquely while orbiting only 26 km above the lunar surface. A 327 mb full res image can be downloaded, and a video is available. But I like this overview panorama because it feels like the view out the porthole of a transport vehicle coming in for a landing - or a crash. Aristarchus formed on the boundary of the uplifted Aristarchus Plateau and the surrounding mare lavas, accounting for the bright and dark bands and clumps of material along the walls. Mark suggests that the prominent dark band left of center is impact melt, and some of the smaller dark strands coming from the rim crest down the wall is pyroclastic material. The immediate surrounding of the rim does look like it is mantled with dark powdery material, but that idea leaves me confused because Aristachus is a very young crater with an estimated age of about 0.5 b.y. Volcanism on the Moon largely stopped by 2 b.y. ago with only small eruptions of mare basalts dribbling out at 1 b.y. ago. Such high resolution views as LRO provides will allow relations between multiple geologic units to be examined in great detail.
10 November 2011
Rükl plate 18
Yesterday's LPOD: Santa Moon
Tomorrow's LPOD: Two Friends in the Sky, Two Friends On Earth