I was going to set my gear out this evening for a night of photometry and spectroscopy, but some things cropped up forcing me to call it a night early, Instead, I set out my little Orion tabletop Mak and took in a quick peek at the moon. One feature that caught my eye is the Grimaldi impact basin on the southwestern shore of Oceanus Procellarum. Grimaldi itself is easy to se, but the outer ring of mountains that mark the outer extent of the impact basin are usually hard to detect except when the shadows are just right, as they are this evening. If you take a close look at the Grimaldi region you can see the partial ring of mountains looping around to the south on a radius about twice that of the Grimaldi itself (the northern range associated with the original ring has been obliterated). The Grimaldi system reminds me of a much smaller version of the complete Mare Orientale impact basin that lies just to the west (and might become briefly visible as the moon becomes full) and the partial Mare Nectaris impact basin far off to the east (which tends to stand out when the moon is a waning gibbous).

-John