Bolyai is an old

lunar Lunar most commonly means "of or relating to the Moon". Lunar may also refer to: Arts and entertainment * ''Lunar'' (series), a series of video games * "Lunar" (song), by David Guetta * "Lunar", a song by Priestess from the 2009 album ''Prior t ...

impact crater An impact crater is a depression (geology), depression in the surface of a solid astronomical body formed by the hypervelocity impact event, impact of a smaller object. In contrast to volcanic craters, which result from explosion or internal c ...

that is located in the southern

hemisphere Hemisphere may refer to: In geometry * Hemisphere (geometry), a half of a sphere As half of Earth or any spherical astronomical object * A hemisphere of Earth ** Northern Hemisphere ** Southern Hemisphere ** Eastern Hemisphere ** Western Hemi ...

on the

far side of the Moon The far side of the Moon is the hemisphere of the Moon that is facing away from Earth, the opposite hemisphere is the near side. It always has the same surface oriented away from Earth because of synchronous rotation in the Moon's orbit. C ...

. To the southeast of Bolyai is the crater Eötvös, and to the north is

Neujmin Grigory Nikolayevich Neujmin (; – 17 December 1946) was a Georgian–Russian astronomer, native of Tbilisi in Georgia (country), Georgia, and a discoverer of numerous minor planets as well as 6 periodic comet, periodic and a List of hyperbolic ...

. It is named after the 19th century Hungarian mathematician

János Bolyai János Bolyai (; ; 15 December 1802 – 27 January 1860) or Johann Bolyai, was a Hungarian mathematician who developed absolute geometry—a geometry that includes both Euclidean geometry and hyperbolic geometry. The discovery of a consist ...

. This crater has been heavily eroded and worn by subsequent impacts, leaving only a deformed remnant of the original rim that is overlaid by a multitude of lesser craters. The most notable of these is Bolyai D along the northeast rim and Bolyai W to the northwest. The latter is actually a formation of multiply overlapping craters. The interior of the crater is relatively level, but rough in places due to impacts that have reshaped the surface. Near the rounded central peak, and from there towards the northern rim, is a section of floor that has been resurfaced by

lava Lava is molten or partially molten rock (magma) that has been expelled from the interior of a terrestrial planet (such as Earth) or a Natural satellite, moon onto its surface. Lava may be erupted at a volcano or through a Fissure vent, fractu ...

flows. This area is smoother than the remainder of the floor, and has a lower

albedo Albedo ( ; ) is the fraction of sunlight that is Diffuse reflection, diffusely reflected by a body. It is measured on a scale from 0 (corresponding to a black body that absorbs all incident radiation) to 1 (corresponding to a body that reflects ...

, giving it a dark appearance.

Satellite craters

By convention these features are identified on lunar maps by placing the letter on the side of the crater midpoint that is closest to Bolyai.

References

* * * * * * * * * * * * Impact craters on the Moon {{Craters on the Moon: A–B