Bullialdus is a

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 ...

located in the western part of the

Mare Nubium Mare Nubium (Latin ''nūbium'', the "sea of clouds") is a lunar mare in the Nubium basin on the Moon's near side. The mare is located just to the southeast of Oceanus Procellarum. Formation The basin containing Mare Nubium is believed to ha ...

. It was named after French astronomer

Ismaël Boulliau Ismaël is a given name or surname, and may refer to: * Ismaël Aaneba (born 1999), French footballer * Ismaël Alassane (born 1984), Nigerian football defender * Ismaël Ankobo (born 1997), Congolese footballer * Ismaël Bangoura (born 198 ...

. To the north by north-west is the broken-rimmed and lava-flooded crater Lubiniezky. South-west of Bullialdus lies the smaller crater

König König (; ) is the German word for "king". In German and other languages applying the umlaut, the transliterations ''Koenig'' and ''Kœnig'', when referring to a surname, also occur. As a surname in English, the use of ''Koenig'' is usual, and som ...

. The relatively isolated location of this crater serves to highlight its well-formed shape. Bullialdus has a high outer rim that is circular but observers have noted a slightly polygonal appearance. The inner walls are

terrace Terrace may refer to: Landforms and construction * Fluvial terrace, a natural, flat surface that borders and lies above the floodplain of a stream or river * Terrace, a street suffix * Terrace, the portion of a lot between the public sidewalk a ...

d and contain many signs of landslips. The outer

rampart Rampart may refer to: * Rampart (fortification), a defensive wall or bank around a castle, fort or settlement Rampart may also refer to: * "O'er the Ramparts We Watched" is a key line from "The Star-Spangled Banner", the national anthem of the ...

s are covered in a wide ''ejecta'' blanket that highlights a radial pattern of low ridges and valleys. In the center of the crater is a formation of several peaks and rises that climb to over a kilometer in height. A raised ridge runs from the peaks to the south-east, until finally merging with the inner wall. The floor of the crater is generally rough with many low rises. Overall it has a somewhat convex shape, bulging upward toward the middle. When the Sun is at a high angle, the rim and central mountains appear brighter than the surroundings, and white patches can be viewed on the crater floor.

Infrared Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from around ...

studies of the crater region have revealed at least three layers of strata. The impact may also have intersected a

mafic A mafic mineral or rock is a silicate mineral or igneous rock rich in magnesium and iron. Most mafic minerals are dark in color, and common rock-forming mafic minerals include olivine, pyroxene, amphibole, and biotite. Common mafic rocks include ...

pluton In geology, an igneous intrusion (or intrusive body or simply intrusion) is a body of intrusive igneous rock that forms by crystallization of magma slowly cooling below the surface of the Earth. Intrusions have a wide variety of forms and com ...

, which means a

crystal A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. In addition, macros ...

lized body of

igneous rock Igneous rock (derived from the Latin word ''ignis'' meaning fire), or magmatic rock, is one of the three main The three types of rocks, rock types, the others being Sedimentary rock, sedimentary and metamorphic rock, metamorphic. Igneous rock ...

that has high concentrations of heavier elements (such as

magnesium Magnesium is a chemical element with the symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point and high chemical reactivity. Like the other alkaline earth metals (group 2 of the periodic ta ...

, in this case). Two smaller but notable craters lie just to the south of the main crater. Bullialdus A lies just to the south-west of Bullialdus, within its ramparts. To the south of Bullialdus A is the slightly smaller Bullialdus B.

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 Bullialdus.

References

* S. Tompkins ''et al.'', "Distribution and geologic history of materials excavated by the lunar crater Bullialdus", ''Twenty-Fourth Lunar and Planetary Science Conference'', Part 3, 1993. * * * * * * * * * * * *

External links

Central Peak of Bullialdus Crater
Lunar Reconnaissance Orbiter Camera, Posted by Samuel Lawrence on May 11, 2010.
Bullialdus Central Peak Oblique
Lunar Reconnaissance Orbiter Camera, Posted by Sarah Braden on January 23, 2013. * * * * * * Impact craters on the Moon {{Craters on the Moon: A–B