[crater] Fechner is a lunar crater that lies on the far side of the Moon`s southern hemisphere, attached to the western rim of the large walled plain Planck. The eastern rim of Fechner intersects the Vallis Planck, a long, wide cleft in the surface that follows a course to the north-northwest. This valley intrudes into the southeastern rim ... Found on http://en.wikipedia.org/wiki/Fechner_(crater)