Geological Chronicle
Rimae Secchi is a system of rilles in northwestern Mare Fecunditatis, running along the shore of the mare. The structure extends along the northwestern rim of an 85-kilometer ghost crater filled by lava.
The northern end of the system is Y-shaped and surrounded by a dark halo of probable pyroclastic volcanic ash. To the south, the structure divides into several separate troughs.
During preparation for the Apollo 8 and Apollo 10 missions, the rilles were informally nicknamed the Apollo Rille. The International Astronomical Union officially approved the name Rimae Secchi in 1985, deriving the designation from nearby crater Secchi and Italian astronomer Angelo Secchi.