Geological Chronicle
Jacobi occupies a crowded sector of the Moon's southern highlands, positioned southeast of Lilius and between Cuvier to the north-northwest and Baco to the northeast. Formed during the Pre-Nectarian period between 4.55 and 3.92 billion years ago, the crater spans a diameter of 66.28 kilometers and drops to a depth of 3.3 kilometers below its eroded crest.
Subsequent bombardment has degraded the perimeter. Smaller impacts punctuate the rim, including Jacobi J on the southern wall and a pair of craters to the north, giving the structure a distinctly flattened profile along its northern and southern edges. Jacobi O, the larger member of the northern pair, anchors an irregular chain of craters that cuts northeast to southwest across the interior floor and merges into tiny overlapping depressions near the center.
Beyond this interior chain, the remainder of Jacobi's floor is level, having been smoothed by erosion or deposits of impact debris. To the south, the overlapping triplet of Jacobi F, Jacobi E, and Jacobi G forms another linear feature. The International Astronomical Union named the formation in 1935 in honor of the Prussian mathematician Carl Gustav Jacob Jacobi.