Korolev L crater, Apollo 8 image, 1968. This image shows the Korolev L crater (centre) on the far side of the Moon. The crater is about 31 kilometres across, and has a smaller crater within it. The elongated crater below Korolev L was nicknamed 'The Keyhole'. This area is within a much larger crater (Korolev) that is 437 kilometres across. The Apollo 8 mission took place from 21 to 27 December 1968. This image was obtained with a Hasselblad camera while the Apollo 8 spacecraft was orbiting the Moon. This was the first time humans had directly viewed the far side of the Moon.