Geological Chronicle
Situated on the lunar far side south of Mare Moscoviense, Tsu Chung-Chi spans 28.53 kilometers in diameter between the walled plain Mendeleev and the crater Leonov. The structure forms a bowl-shaped depression slightly elongated toward the northwest, with simple sloping walls that descend directly to the floor. Subsequent impacts have eroded the formation, leaving a small, cup-shaped crater intruding slightly into its southern rim alongside several tiny craterlets across the interior floor.
The crater was among roughly 500 features identified on photographs made by Luna 3 in 1959. When the Keldysh Commission prepared names for the newly photographed formations, instructions from the Soviet Central Committee specified that the roster must include an American and a Chinese figure. While Soviet planners readily agreed on Thomas Edison, selecting a Chinese candidate required consultations between Soviet officials and the Chinese embassy, which relayed the request to Beijing.
The Praesidium of the Academy of Sciences ultimately approved naming the crater for fifth-century mathematician and astronomer Zu Chongzhi. According to memoirs from rocket engineer Boris Chertok, Zu proved the most controversial candidate because Soviet mathematicians were unfamiliar with his work, but his selection secured the required diplomatic representation alongside Western figures such as Maxwell, Hertz, and Edison.