On the south shore of Mare Nectaris can be found a number of lunar treasures to occupy and evening of pleasant observing. The first thing a newcomer might notice is the great “U” shaped feature that is Fracastorius (128 km dia.). If your telescope is large enough, magnification high enough and the lighting right, you will notice a faint smile on the floor of this partially submerged crater, a rima with a bend in the middle. There is more to the rima than seen here but you will need a good sized telescope and just the right lighting to see it all. On the south shore of Fracastorius is a curious feature called Fracastorius Y. Prior to spacecraft, this was the subject of much speculation as to its nature. Today we can see in LROC Quick Map that it is the merge of 3 craters with post-impact modification. In fact, from this feature up to the crater just north of it, Fracastorius D on the east (left) side of Fracastorius, there are a lot of curious forms. To the upper left from Fracastorius can be seen a smaller version of this crater, Beaumont (54 km). Both craters are flooded with their north walls breached by magma from the Nectaris impact some 3.8-3.9 billion years ago.
Moving south across this rugged landscape (selenoscape?) we come to a notable crater near the bottom of this image, Piccolomini (90 km) with beautifully terraced walls save on the south side where there was apparently a collapse. Notice that it sits at the south end of a scarp, the outer wall of the M. Nectaris impact, called Rupes Altai. It is an impressive 495 km long cliff that runs from Piccolomini north to just west of the crater Catharina (104 km).
There are many other features to explore in this region like the hoof-print crater north of Piccolomini, or the two craters that share a straight wall between them just south of Catharina, or the interesting ejecta cluttered floor of Pons. (I’ll let you find that last one for yourself!)
