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.

Chuck Wood

Technical Details
10 November 2011

Related Links
Rükl plate 18

Yesterday's LPOD: Santa Moon

Tomorrow's LPOD: Two Friends in the Sky, Two Friends On Earth

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