Geological Chronicle
Buys-Ballot is an asymmetric impact crater on the Moon's far side, positioned north of the center of the Freundlich-Sharonov Basin and northwest of Lacus Luxuriae. The formation deviates sharply from circular crater geometry, displaying a prominent southern elongation that nearly doubles its length compared to its east-west cross section. Planetary scientists interpret this pear-like outline as the product of an oblique impact originating from the north. The wider northern bulge spans roughly 50 kilometers across, while the narrower southern extension adds another 20 kilometers to the structure.
A central ridge runs along the longest axis of the crater, dividing the southern half of the interior floor before terminating near the widest section of the basin. The northern floor contains an oval patch of basaltic lava that has partially resurfaced the terrain, displaying a lower albedo than the surrounding regolith. Spectral analyses indicate that this basaltic deposit contains an estimated 8 to 15 weight percent iron and up to 2 weight percent titanium. In contrast to this smooth volcanic patch, the remainder of the crater floor remains rough and irregular, marked by minimal subsequent impact erosion.
At the northern rim lie the paired satellite craters Buys-Ballot Y and Z, which form a near-mirror configuration joined by a slender central ridge. Both satellites extend twice as far to the north as their individual east-west dimensions, with the northwest wall showing the infrared spectral signature of pure crystalline plagioclase. Named in honor of Dutch meteorologist Christoph Hendrik Diederik Buys Ballot, the feature's name was officially adopted by the International Astronomical Union in 1970.