Ritter is a lunar impact crater located near the southwestern edge of Mare Tranquillitatis.

In To A Rocky Moon, lunar geologist Don E. Wilhelms summarized: "They are identical twins in morphology and size (29-30 km).

They lack radial rim ejecta and secondary craters despite their apparent youth.

Most significant, they lack deep floors recognized since the days of Gilbert as diagnostic of impacts."

"[2] By convention these features are identified on lunar maps by placing the letter on the side of the crater midpoint that is closest to Ritter.