Pingré (crater)

Pingré (crater)
Name	Pingré
Diameter	71 km
Depth	2.7 km
Colong	42
Eponym	Alexandre G. Pingré

Pingré (crater) is a lunar impact crater located near the southwestern limb of the Moon on the near side, notable for its eroded rim and relatively flat floor. It lies in a region observed by many missions and astronomers, and its morphology records processes tied to mare emplacement, impact cratering, and secondary modification. The feature has been imaged by Lunar Reconnaissance Orbiter, Apollo 16, and earlier by Luna programme and Clementine assets, and is a subject for selenographers and planetary geologists alike.

Description

Pingré is an impact structure with a diameter of approximately 71 kilometers and a depth near 2.7 kilometers, presenting a worn, irregular rim and a floor marked by low ridges and small craterlets. Observers from Giovanni Battista Riccioli era nomenclature through modern catalogs have noted its subdued relief relative to fresher craters such as Copernicus (lunar crater), Tycho (crater), and Kepler (crater). The rim exhibits breaches and outward bulges toward adjoining basins like Mare Humorum and features slumped inner walls comparable to those of Gassendi (crater) and Humboldt (crater). Ejecta patterns around Pingré are faint when contrasted with young rays from Tycho or Giordano Bruno (crater).

Location and Surroundings

Pingré is situated near the southwestern limb of the lunar near side, south of Mare Humorum and northwest of Schiller (crater), with neighboring features including Davy (crater), Wargentin (crater), and Wright (crater). Its coordinates place it within a region mapped by Johannes Hevelius and later detailed by Johann Heinrich von Mädler and Wilhelm Beer; modern cartography by United States Geological Survey lunar charts and International Astronomical Union nomenclature confirms its placement near selenographic latitude ~ -33° and longitude ~ -42°. The proximity to mare basalts of Mare Humorum links Pingré to basaltic plains explored in sample-return contexts such as Apollo 15 and remote-sensing campaigns by Chandrayaan-1 and Kaguya (SELENE). Satellite craters conventionally assigned letters (e.g., Pingré A, Pingré B) lie around the main rim, intermingled with wrinkle ridges and nearby graben features similar to those observed in Marius Hills and Vallis Schroteri.

Geology and Morphology

The crater's geology reflects impact-generated breccias, fractured bedrock, and volcanic resurfacing influences from adjacent mare activity. The floor shows relatively low albedo patches akin to mare basalts studied at Mare Imbrium and stratigraphically compared to flows analyzed by Apollo 12 and Apollo 15 geologists. Rim degradation indicates significant mass wasting and seismic shaking from later impacts comparable to ejecta loading seen near Orientale basin and Imbrium basin. Small central peaks are absent or heavily eroded, resembling the subdued interiors of Ptolemaeus (crater) and Albategnius (crater), while secondary craters and rays from large impacts like Tycho have contributed micro-scale regolith gardening. Remote-sensing spectrometers aboard Moon Mineralogy Mapper and instruments on Lunar Reconnaissance Orbiter have characterized mineralogical signatures reflective of pyroxene and plagioclase mixes comparable to analyses from Lunar Prospector and SMART-1.

Age and Stratigraphy

Relative dating places Pingré in the Nectarian to Imbrian transition, older than many Copernican-age craters yet younger than the primordial highland crust sampled by Lunar meteorites and Apollo samples from South Pole–Aitken basin ejecta. Stratigraphic relationships with Mare Humorum basalts and superposed crater counts align Pingré with the Lower Imbrian epoch in lunar stratigraphy used by teams at NASA and the USGS; this is corroborated by crater degradation state studies similar to those performed for Clavius (crater) and Schickard (crater). Its ejecta blanket is subdued, indicating substantial space weathering and micrometeorite gardening over geologic time, comparable to lunar far-side highlands cataloged by Chang'e 1 and Luna 16 analyses.

Observation and Exploration

Pingré has been observed telescopically since the era of telescopic selenography by Galileo Galilei, Christiaan Huygens, and later mapped by Giovanni Cassini and Johann Schmidt, and imaged extensively during the photographic era by Lunar Orbiter missions. High-resolution imagery and altimetry from Lunar Reconnaissance Orbiter Camera (LROC) and LOLA have detailed its topography, while spectral data from Clementine and Moon Mineralogy Mapper inform compositional studies. Pingré's visibility from Earth is foreshortened near libration extremes noted by observational programs at Royal Astronomical Society facilities and amateur groups organized through International Astronomical Union outreach. No landed missions have targeted Pingré directly, but orbital datasets from Apollo Command Module photography, Kaguya terrain camera, and Chang'e 2 provide substantial remote observations applicable to future mission planning by agencies such as ESA, Roscosmos, CNSA, and ISRO.

Nomenclature and Etymology

The crater is named for the French astronomer and cartographer Alexandre Guy Pingré, whose work in the 18th century on cometary observations and nautical almanacs influenced contemporary celestial cataloging used by figures like Charles Messier and Pierre Méchain. The designation was standardized by the International Astronomical Union following conventions applied to lunar features first systematized in editions by Mary Adela Blagg and Karl Müller. Historical appellations and map labels appear in atlases by Giovanni Riccioli and later revisions by Wilhelm Beer and Johann Heinrich von Mädler, linking Pingré to the lineage of European selenographers and the broader tradition of naming lunar craters after notable astronomers, mathematicians, and navigators such as Tycho Brahe, Johannes Kepler, and Galileo Galilei.

Category:Lunar impact craters