Geological Chronicle
Gemma Frisius is a lunar impact crater in the Moon's rugged southern highlands, situated north of the walled plain Maurolycus and southeast of the crater Poisson. With a diameter of 88.54 kilometers, it is named after Dutch physician Gemma Frisius. The crater Goodacre is attached to its northeast rim.
Impacts have heavily damaged the outer wall of Gemma Frisius, particularly along its north and west sides, where satellite craters D, G, and H are attached. Observers have noted that this formation resembles a paw print with four toes, with Goodacre and the three satellites forming the digits.
The southeastern rim is also worn, and the inner wall has slumped nearly a third of the distance across the interior floor. The remainder of the floor is relatively level and deep, with a central peak that is offset to the northwest of the midpoint.