Geological Chronicle
Pasteur is an ancient lunar walled plain measuring 232.77 kilometers in diameter, located on the far side of the Moon just beyond the eastern limb. Because of lunar librations, its vicinity is occasionally brought into view from Earth, although little surface detail can be discerned. Named after French chemist and microbiologist Louis Pasteur, the formation dates to the Pre-Nectarian period of the lunar geologic timescale.
Multiple overlapping impacts have heavily damaged the outer perimeter, nearly obliterating the northern rim. The southern rim is overlain by the smaller crater Backlund, and the southeastern margin runs nearly linear where modified by the adjacent walled plain Hilbert. Overlying craters Pasteur U, Anders' Earthrise, and Pasteur Q degrade the western rim, where Pasteur T was renamed Anders' Earthrise in October 2018.
The crater interior is similarly battered, with impact ejecta covering the southern half and small craters scattered across the floor. A short chain of overlapping craters forms an arcing north-to-south line across the northwestern floor, while satellite craters Pasteur G and Pasteur H form a pair east of the midpoint. To the northeast, the fresh Copernican-period crater Pasteur D possesses a ray system and exhibits an extremely high rockfall density by lunar standards.