April 18, 2012
image by George Tarsoudis, Greece
George has made an exquisite capture of the far western side in Mare Imbrium. Near the terminator is a series of mare ridges that are partly concave to Imbrium with others that slightly open to the west. Touching one ridge near top right is a rimless pit - either an impact crater surrounded and partially inundated by mare lavas or a volcanic collapse pit. Near the center of the scene are the two post mare craters - as you can tell because their ejecta ridges sit on the lava surface. Northeast of Delisle is the slot vent of the Delisle Rille, and parts of the Diophantus Rille snake between the two D craters. George nicely captured the small depression north of Artsimovich, and he correctly points out that it is not an impact crater. It is an oval-shaped volcanic collapse pit. Another one is above the .com in George's website address at bottom left. The white map with numbers is from an earlier compilation of lunar domes by the late Charlie Kapral. George's low Sun image provides no support for the existence of domes 478, 479 and 487, but based on topo transects from the LRO QuickMap 502 is a 60 to 80 m high dome. Congratulations to the telescopic observers who first noticed it. Finally, there is one more type of subtle volcanic feature in this great image. Running nearly south to north near the right margin are one of two of the famous young volcanic flows that rushed across this part of Imbrium about 2.5 billion years ago.
04 April 2012 @17:56 UT. 10 inch @f/6.3, camera Unibrain fire-i 785, filter red, barlow 3X.
Rükl plate 3
Yesterday's LPOD: A Little Night Video
Tomorrow's LPOD: A New Treasure