Pasteur is a large lunar impact crater, approximately 233 kilometers in diameter, belonging to the category termed a walled plain.

The outer rim of Pasteur is generally irregular, with sections being heavily damaged by multiple impacts.

The interior is not in much better shape, with the southern half irregular from ejecta covering the surface, and several small craters lying across the floor.

In the northwest part of the floor is a short chain of small, overlapping craters forming an arcing line from north to south.

[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 Pasteur.