Kästner is a lunar impact crater that is located near the eastern limb of the Moon, to the southwest of the Mare Smythii.

To the south is the prominent crater Ansgarius, and to the southwest lies La Pérouse.

The interior floor is relatively level and featureless, with only a few small craters and minor ridges.

[2] By convention these features are identified on lunar maps by placing the letter on the side of the crater midpoint that is closest to Kästner.

Kästner B, R, and S are called Defoe, Shekhov, and Cellini on some older maps,[3] but these names were not approved by the IAU.