Regiomontanus is an ancient

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 ...

located in the southern highlands region to the southeast of

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 ...

. It is joined at the chaotic northern rim by the crater Purbach, and to the south-southeast is

Walther Walther () is a masculine given name and a surname. It is a German form of Walter, which is derived from the Old High German '' Walthari'', containing the elements ''wald'' -"power", "brightness" or "forest" and ''hari'' -"warrior". The name was ...

Characteristics

The crater is heavily worn from impact

erosion Erosion is the action of surface processes (such as Surface runoff, water flow or wind) that removes soil, Rock (geology), rock, or dissolved material from one location on the Earth's crust#Crust, Earth's crust and then sediment transport, tran ...

, and the rim is irregular, mountainous and distinctly oval in outline. The walls on the southern and western edges have been almost completely degraded. A prominent ridge lies off-center to the northwest, with the small crater Regiomontanus A at its summit. The crater floor is

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 ...

-flooded, and has a number of small crater impacts. The summit crater Regiomontanus A was once considered proof of

volcanic A volcano is commonly defined as a vent or fissure in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most often fo ...

activity on the Moon. However this feature is actually an impact crater, and is offset slightly from the summit of the central peak.

Name

Regiomontanus is named after the 15th century German astronomer and mathematician Johannes Müller von Königsberg, known as

Regiomontanus Johannes Müller von Königsberg (6 June 1436 – 6 July 1476), better known as Regiomontanus (), was a mathematician, astrologer and astronomer of the German Renaissance, active in Vienna, Buda and Nuremberg. His contributions were instrument ...

. Like many of the craters on the Moon's near side, it was given its name by

Giovanni Riccioli Giovanni Battista Riccioli (17 April 1598 – 25 June 1671) was an Italian astronomer and a Catholic priest in the Jesuit order. He is known, among other things, for his experiments with pendulums and with falling bodies, for his discussion of ...

, whose 1651 nomenclature system has become standardized. Earlier lunar cartographers had given the feature different names.

Michael van Langren Michael van Langren (April 1598 May 1675) was an astronomer and cartographer of the Low Countries. A Catholic, he chiefly found employment in service to the Spanish Monarchy. Family Michael van Langren was the youngest member of a family of Du ...

's 1645 map calls it "Christinae Reg. Suec." after

Christina, Queen of Sweden Christina (; 18 December O.S. 8 December">Old_Style_and_New_Style_dates.html" ;"title="nowiki/>Old Style and New Style dates">O.S. 8 December1626 – 19 April 1689), a member of the House of Vasa, was Monarchy of Sweden, Queen of Sweden from ...

. And

Johannes Hevelius Johannes Hevelius Some sources refer to Hevelius as Polish: * * * * * * * Some sources refer to Hevelius as German: * * * * *of the Royal Society * (in German also known as ''Hevel''; ; – 28 January 1687) was a councillor and mayor of Danz ...

grouped it with Purbach and

as "Mons Libanus" after

Mount Lebanon Mount Lebanon (, ; , ; ) is a mountain range in Lebanon. It is about long and averages above in elevation, with its peak at . The range provides a typical alpine climate year-round. Mount Lebanon is well-known for its snow-covered mountains, ...

.Ewen A. Whitaker, ''Mapping and Naming the Moon'' (Cambridge University Press, 1999), p. 205.

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 Regiomontanus.

References

* * * * * * * * * * * {{Commons category Impact craters on the Moon