Oken is a lunar crater near the southeastern limb of the Moon. It is normally visible from the Earth, but is foreshortened and within the region of the surface that is subject to libration. To the south and east of this feature is the broad, uneven Mare Australe, which extends to the far side of the Moon.

German naturalist whose speculations that plants and animals are made up of tiny living `infusoria' led to the cell theory (1779-1851)