May 9, 2021
Originally published September 20, 2011
image by Alexander N. Zaitsev, Lipetsk, Russia
What is the relationship between Bürg and Lacus Mortis? Obviously Bürg is younger because it sits on top of LM. And Bürg is younger than the lava filling that covers LM's floor. It is peculiar that two ridges from LM's rim meet in its center, which Bürg is slightly east of, and that there is very little of Bürg's continuous ejecta on that side. Is the lava to the west of Bürg younger than the crater, covering the ejecta? Looking at a LRO hi res mosaic there are far fewer craters in one patch of mare just west of Bürg than elsewhere on the west half of the floor, so the answer is yes. The trough-like rille is older than Bürg because in some parts it is filled by the crater's ejecta. It is less clear if the fault that becomes a rille is effected by Bürg's ejecta - it could have formed after the crater. I still don't know why so many tectonic features occur in LM, and all on the western half. LM is not a floor-fractured crater, it is a peculiar crater.
2011/09/16 Time:21:10:46 UT. Telescope SW 305/1500 + Camera VAC-135 (b/w 15 fps) with the red filter and barlow 4X
Rükl plate 14
Yesterday's LPOD: 3x Giant
Tomorrow's LPOD: Before And Way After