The far side of the Moon is the lunar hemisphere that is permanently turned away from the Earth. The far hemisphere was first photographed by the Soviet Luna 3 probe in 1959, and was first directly observed by human eyes when the Apollo 8 mission orbited the Moon in 1968. The rugged terrain is distinguished by a multitude of crater impacts, as well as relatively few lunar maria. It includes the second largest known impact feature in the Solar System, the South Pole-Aitken basin. The far side has been suggested as a potential location for a large radio telescope, as it would be shielded from possible radio interference from Earth.