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 circular depression in the surface of a solid astronomical object formed by the hypervelocity impact of a smaller object. In contrast to volcanic craters, which result from explosion or internal collapse, impact craters ...

that is located in the southern

hemisphere Hemisphere refers to: * A half of a sphere As half of the Earth * A hemisphere of Earth ** Northern Hemisphere ** Southern Hemisphere ** Eastern Hemisphere ** Western Hemisphere ** Land and water hemispheres * A half of the (geocentric) celestia ...

on the

far side of the Moon The far side of the Moon is the lunar hemisphere that always faces away from Earth, opposite to the Near side of the Moon, near side, because of synchronous rotation in the Moon's orbit. Compared to the near side, the far side's terrain is ru ...

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

Neujmin Grigory Nikolayevich Neujmin (russian: Григорий Николаевич Неуймин; – 17 December 1946) was a Georgian–Russian astronomer, native of Tbilisi in Georgia (country), Georgia, and a discoverer of numerous minor planets as ...

. 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 consisten ...

. 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 moon onto its surface. Lava may be erupted at a volcano or through a fracture in the crust, on land or un ...

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

albedo Albedo (; ) is the measure of the diffuse reflection of sunlight, solar radiation out of the total solar radiation and measured on a scale from 0, corresponding to a black body that absorbs all incident radiation, to 1, corresponding to a body ...

, 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