Moon: East Region

Several smaller mares extend through the Eastern Region including the especially dark Mare Tranquillitatis. An oblique ray system associated with Proclus neighbours Mare Crisium and a glancing impact created Messier’s even more unusual ray pattern on Mare Fecunditatis. The most notable craters in the Eastern Region are the well-formed Theophilus with its complex central mountains and the progressively more degraded craters Cyrillus and Catharina.