Geological Chronicle
Letronne is a lava-flooded lunar impact crater spanning 117.59 kilometers in diameter along the southwestern shore of Oceanus Procellarum. Its northern rim is completely missing, opening the crater into the surrounding mare like a wide bay. Located to the northwest of the large crater Gassendi, Letronne survives as a semi-circular series of ridges rising above the plain.
The formation dates to the Early Imbrian epoch, making it one of the largest craters preserved from that period of lunar history. Its western wall is breached and overlain by the flooded rim of Winthrop crater, whereas the eastern stretch remains the most intact section, forming a mountainous promontory into the mare.
A small cluster of central rises lies at the midpoint of the crater floor. The wrinkle ridge Dorsa Rubey traverses the floor from north to south, outlining a portion of the missing rim across an otherwise smooth volcanic surface. The crater was named for French archaeologist Jean-Antoine Letronne.