Joly is an impact crater on Mars, located at 74.7°S latitude and 42.7°W longitude in the Mare Australe quadrangle. It measures 79.9 kilometres (49.6 mi) in diameter and was named after Irish physicist John Joly (1857–1933). The name was approved in 1973, by the International Astronomical Union (IAU) Working Group for Planetary System Nomenclature (WGPSN).[1]