Lunar Crater Piccolomini

On Thursday evening, December 5, the curved terminator on the moon will fall just to the left (or lunar west) of ancient Mare Nectaris, the dark and roughly circular patch located just south of the moon’s equator. A prominent crater named Piccolomini is located in the lunar highlands a small distance to the lower left of Nectaris. The 55 miles (88 km) wide crater has a sharp rim and a tall central mountain peak. A backyard telescope will show that the central peak is complex and that the crater’s inner walls have collapsed to form terraces. Watch for the curved escarpment named Rupes Altai extending to the upper left (or lunar northwest) from Piccolomini. Piccolomini and Nectaris are highlighted every lunar month when the waxing moon is about 5 days past new and again when the waning moon is approaching third quarter.