Geological Chronicle
Hilbert is a lunar impact crater spanning 173.24 kilometers across on the far side of the Moon, just past the southeastern limb. It lies beyond the zone brought into view by libration, so it cannot be observed directly from Earth. The crater attaches to the southeast rim of the walled plain Pasteur, a formation nearly half as large again as Hilbert. The smaller crater Alden lies to the southeast, and Backlund sits to the west-northwest.
The crater's interior is relatively flat, though gouged by several smaller craters. Just west of the midpoint rises a short range of central ridges where the infrared spectrum of pure crystalline plagioclase has been identified. Immediately west of the ridges lies Hilbert W, whose pear-like shape comes from a smaller crater overlying its western rim. The circular, bowl-shaped crater Hilbert H sits on the eastern floor, and Hilbert Y lies next to the northern rim.
Dating to the Nectarian period, Hilbert is one of the largest craters of that age. Much of its outer rim remains intact, although the wall is heavily eroded in places, particularly in the south. The crater also has an extremely high rockfall density by lunar standards.