Poincaré is Ridge Section 159, named after the large (319 km) lunar impact basin that lies in the southern hemisphere on the lunar Far Side.  Google searches turned up a voluminous amount of information on this area of the Moon.  Most of the Poincare formation has been heavily eroded by subsequent impacts, leaving a battered formation with only rugged remnants of the original outer rim to the west. The eastern half has been completely worn away, and much of the interior has been resurfaced by lava flows. This surface has a lower albedo than the surrounding terrain, giving it a dark appearance. A rugged formation forms a low north-south range across the eastern section of the floor, possibly the remnant of an inner ring. The perimeter of Poincaré has several notable craters. To the north is the crater Hopmann, while the craters Abbe and Hess (out of frame) lie to the east. Directly to the west is Planck (also out of frame), a walled plain of similar dimensions to Poincaré. Both formations are sufficiently large to have formed a small lunar mare on the near side face of the Moon. (Credit: Most of the information used in the section feature descriptions was obtained from wikipedia.org. Section 159 and this directory was created by Fran Ridge and Ned Haskin of The Lunascan Project).