Heinsius is an eroded lunar impact crater that lies in the southwestern part of the Moon.

[1] It is located to the northwest of the prominent crater Tycho, and rays from that formation pass to the north and south of Heinsius as well as marking the rim and interior with material.

Together these three satellite craters form a triangular arrangement with the rims only separated by a few kilometers from each other.

The northern half of the rim is in better shape, although still worn and rounded due to impact erosion.

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