Geological Chronicle
Brianchon lies along the Moon’s northwestern limb. From Earth, it is seen at the edge, and its visibility is somewhat affected by libration. A more detailed view requires observing it from orbit. Pascal lies just to its east; Desargues is southeast, Cremona is south along the limb, and Lindblad is southwest on the far side of the Moon.
The formation dates to the Pre-Nectarian period and has been worn and eroded by impacts since its creation. A pair of craters lies across the northern rim, and Brianchon B intrudes slightly into the southern rim. Brianchon A forms an outward bulge in the northwest and otherwise merges seamlessly into the formation. A concentric crater formation intrudes into the exterior of the southeastern rim. The rest of the outer wall is rounded and covered in tiny craterlets.
The floor is pockmarked with tiny craterlets and has a relatively level surface. The most prominent is a small, bowl-shaped crater just northwest of the midpoint. Several tiny craterlets cluster in the southern part of the floor.
The crater is named after French mathematician Charles J. Brianchon (1783–1864). David W. G. Arthur and Ewen Whitaker introduced its name in the Rectified Lunar Atlas, and the International Astronomical Union officially adopted it the next year: introduced in 1963, adopted in 1964.