Alphonsus (crater)

Alphonsus
	LRO image
Coordinates	13°23′S2°51′W / 13.39°S 2.85°W
Diameter	110.54 km
Depth	2.7 km
Colongitude	4° at sunrise
Eponym	Alfonso X

Last updated May 24, 2023

Alphonsus is an ancient impact crater on the Moon that dates from the pre-Nectarian era.^[1] (Older sources state that it is Nectarian in age. ^[2]) It is located on the lunar highlands on the eastern end of Mare Nubium, west of the Imbrian Highlands, and slightly overlaps the crater Ptolemaeus to the north. To the southwest is the smaller Alpetragius. The crater name was approved by the IAU in 1935.^[3]

Description

The surface of Alphonsus is broken and irregular along its boundary with Ptolemaeus. The outer walls are slightly distorted and possess a somewhat hexagonal form.

A low ridge system of deposited ejecta bisects the crater floor, and includes the steep central peak designated Alphonsus Alpha (α). This pyramid-shaped formation rises to a height of 1.5 km above the interior surface. It is not volcanic in origin, but rather is made of anorthosite like the lunar highlands.

The floor is fractured by an elaborate system of rilles and contains four or five smaller craters surrounded by a symmetric darker halo. These dark-halo craters are cinder cone-shaped and are believed by some to be volcanic in origin, although others think they were caused by impacts that excavated darker mare material from underneath the lighter lunar regolith.

Exploration

The Ranger 9 probe impacted in Alphonsus, a short distance to the northeast of the central peak. Harold Urey said of a close-up photograph of Alphonsus:

The floor is covered with many craters of various sizes, some sharp and hence new, others less distinct and partly filled with fragmented material. The walls have fewer craters, and this probably means that slumping of the wall has filled them. Crevasses are evident, and evidence for slumping exists. The larger crater near the top is undoubtedly collisional in origin. Three craters are surrounded by dark halos and were produced by eruptions from the lunar interior. Exceptionally bright, sharp peaks can be seen on certain mountain tops.^[4]

Apollo Landing Site

The dark-haloed craters along some of the rilles in the crater are thought to be volcanic vents, and during the Apollo program Alphonsus was considered as a possible landing site in order to possibly sample xenoliths of the lunar mantle from the vents.^[5] It was considered for Apollo 16 but the Descartes area was selected. It was one of the three final possible sites for Apollo 17, together with Gassendi crater and the Taurus-Littrow valley, but it was considered possibly "contaminated" with younger material from the nearby Imbrium basin.^[6]

Transient lunar phenomena

Alphonsus is one of the sites noted for transient lunar phenomena, as glowing red-hued clouds have been reported emanating from the crater. On October 26, 1956, the lunar astronomer Dinsmore Alter noted some blurring of the rilles on the floor of Alphonsus in the photographs he took in violet light. The same blurring did not occur in the infrared photographs he took at the same time. However, few professional astronomers found this evidence of volcanic activity on the Moon very convincing.^[7]

One astronomer who was intrigued by Alter's observations was Nikolai A. Kozyrev, from the Soviet Union. In 1958 while Kozyrev was looking for volcanic phenomenon on the moon, he observed the formation of a mist-like cloud within Alphonsus.^[8] The spectrum of the area had been measured at this time, and displayed indications of carbon matter, possibly C₂ gas. He believed this to be the result of volcanic or related activity. However no evidence for this phenomenon has been found from lunar missions, and the emission results have never been confirmed.^[9]

Names

Alphonsus is named after King Alfonso X of Castile (known as "Alfonso the Wise"), who had an interest in astronomy.^[10] Like many of the craters on the Moon's near side, it was given its name by Giovanni Riccioli, whose 1651 nomenclature system has become standardized; Riccioli originally named it "Alphonsus Rex" ('King Alfonso'), but the 'Rex' was later dropped.^[11] Earlier lunar cartographers had given the feature different names. Michael van Langren's 1645 map calls it "Ludovici XIV, Reg. Fran.", after Louis XIV of France,^[12] and Johannes Hevelius called it "Mons Masicytus" after a range of mountains in Lycia.^[13]

Interior craters

Five tiny craters in the northeastern part of Alphonsus' interior floor have been assigned names by the IAU. These are listed in the table below.

Crater	Coordinates	Diameter	Name source
Chang-Ngo	12°42′S2°06′W / 12.7°S 2.1°W / -12.7; -2.1	3 km	Chinese goddess of the moon
José	12°42′S1°36′W / 12.7°S 1.6°W / -12.7; -1.6	2 km	Spanish masculine name
Monira	12°36′S1°42′W / 12.6°S 1.7°W / -12.6; -1.7	2 km	Arabic feminine name
Ravi	12°30′S1°54′W / 12.5°S 1.9°W / -12.5; -1.9	2.5 km	Indian masculine name
Soraya	12°54′S1°36′W / 12.9°S 1.6°W / -12.9; -1.6	2 km	Persian feminine name

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 Alphonsus.

Alphonsus	Latitude	Longitude	Diameter
A	14.8° S	2.3° W	4 km
B	13.2° S	0.2° W	24 km
C	14.4° S	4.8° W	4 km
D	15.1° S	0.8° W	23 km
G	12.3° S	3.3° W	4 km
H	15.6° S	0.5° W	8 km
J	15.1° S	2.5° W	8 km
K	12.5° S	0.1° W	20 km
L	12.0° S	3.7° W	4 km
R	14.4° S	1.9° W	3 km
X	15.0° S	4.4° W	5 km
Y	14.7° S	1.8° W	3 km

Related Research Articles

Copernicus is a lunar impact crater located in eastern Oceanus Procellarum. It was named after the astronomer Nicolaus Copernicus. It typifies craters that formed during the Copernican period in that it has a prominent ray system. It may have been created by debris from the breakup of the parent body of asteroid 495 Eulalia 800 million years ago.

Arzachel is a relatively young lunar impact crater located in the highlands in the south-central part of the visible Moon, close to the zero meridian. It lies to the south of the crater Alphonsus, and together with Ptolemaeus further north the three form a prominent line of craters to the east of Mare Nubium. The smaller Alpetragius lies to the northwest, and Thebit is to the southwest along the edge of the mare.

Fra Mauro is the worn remnant of a walled lunar plain. It is part of the surrounding Fra Mauro formation, being located to the northeast of Mare Cognitum and southeast of Mare Insularum. Attached to the southern rim are the co-joined craters Bonpland and Parry, which intrude into the formation forming inward-bulging walls. The crater is named after Italian geographer Fra Mauro.

Albategnius is an ancient lunar impact crater located in the central highlands. It is named after the Mesopotamian Muslim astronomer and scientist Abū ʿAbd Allāh Muḥammad ibn Jābir ibn Sinān al-Raqqī al-Ḥarrānī aṣ-Ṣābiʾ al-Battānī, Latinized as Albategnius.

Ptolemaeus is an ancient lunar impact crater close to the center of the near side, named for Claudius Ptolemy, the Greco-Roman writer, mathematician, astronomer, geographer and astrologer. It measures approximately 154 kilometers in diameter.

Plinius is a prominent lunar impact crater on the border between Mare Serenitatis to the north and Mare Tranquilitatis to the south. Its diameter is 41 km. The crater is named after the Roman natural scientist and author Pliny the Elder. To the south-southeast of Plinius is the crater Ross, and to the northeast is Dawes. Just to the north is a system of rilles named the Rimae Plinius and touching it is the Brackett crater which is more than a crater diameter north. At the northwest edge of the rille is the Promontorium Archerusia, a cape off the western rim that encloses the Mare Serenitatis.

<span class="mw-page-title-main">Hyginus (crater)</span> Volcanic formation on the Moon

Hyginus is a lunar caldera located at the east end of the Sinus Medii. It was named after ancient Roman astronomer Gaius Julius Hyginus. Its rim is split by a 220 kilometer-long rille, Rima Hyginus, that branches to the northwest and to the east-southeast. The crater is deeper than the rille, and lies at intersection of the rille's branches. Together, the crater and the rille form a prominent feature in an otherwise flat surface. Smaller craters along the length of the rille may have been caused by the collapse of an underlying structure.

Alpetragius is a lunar impact crater located on the eastern edge of Mare Nubium, to the southwest of the much larger crater Alphonsus. In the southeast is the prominent crater Arzachel, and to the west lies the flooded Lassell. Alpetragius is a Latinization of the name of Nur ad-Din al-Bitruji, a Spanish-Arab astronomer.

Burnham is a small crater located to the southeast of the crater Albategnius, in a relatively smooth area of the lunar surface. It was named after American astronomer Sherburne W. Burnham. To the southwest is Vogel.

Taruntius is a lunar impact crater on the northwestern edge of Mare Fecunditatis. It was named after ancient Roman philosopher, mathematician and astrologer Lucius Tarutius Firmanus. To the northwest is the lava-flooded crater Lawrence, and to the north lie the craters Watts and da Vinci.

Bode is a small crater located near the central region of the Moon, to the northwest of the joined craters Pallas and Murchison. It lies on a region of raised surface between the Mare Vaporum to the northeast, Sinus Aestuum to the west, and Sinus Medii to the southeast. The crater was named after German astronomer Johann Elert Bode.

Gassendi is a large lunar impact crater feature located at the northern edge of Mare Humorum. It was named after French astronomer Pierre Gassendi. The formation has been inundated by lava during the formation of the mare, so only the rim and the multiple central peaks remain above the surface. The outer rim is worn and eroded, although it retains a generally circular form. A smaller crater – Gassendi A – intrudes into the northern rim, and joins a rough uplift at the northwest part of the floor. The crater pair bear a curious resemblance to a diamond ring.

Triesnecker is a prominent lunar impact crater that is located in the Sinus Medii, near the central part of the Moon's near side. Its diameter is 25 km. It was named after Austrian astronomer Franz de Paula Triesnecker. It is located to the north-northwest of the crater Rhaeticus, and to the east-southeast of the flooded Murchison.

Dionysius is a lunar impact crater that lies on the western edge of the Mare Tranquillitatis. It was named after Dionysius the Areopagite. To the southeast is the crater pair of Ritter and Sabine. Just to the northwest is the system of rilles designated Rimae Ritter. These clefts follow a generally northwest direction.

Littrow is a lunar impact crater that is located in the northeastern part of the Moon's near side, on the east edge of Mare Serenitatis. Its diameter is 29 km. The crater is named after Bohemian astronomer Joseph Johann Littrow. Some distance to the northeast is the prominent crater Römer, while to the south is Vitruvius.

<span class="mw-page-title-main">Ritter (crater)</span> Crater on the Moon

Ritter is a lunar impact crater located near the southwestern edge of Mare Tranquillitatis. Its diameter is 29.5 km. It was named after German geographer Carl Ritter and German astrophysicist August Ritter.

Sosigenes is a lunar impact crater on the west edge of Mare Tranquillitatis. Its diameter is 17 km. It was named after ancient Greek astronomer Sosigenes of Alexandria. It lies to the east of the large walled plain Julius Caesar. The crater rim has a high albedo, making it relatively bright. It has a small central rise at the midpoint of the floor.

Davy is a small lunar impact crater that is located on the eastern edge of the Mare Nubium. It was named after British physicist Humphry Davy. It overlies the lava-flooded remains of the satellite crater Davy Y to the east, a formation which contains a crater chain designated Catena Davy. To the southeast of Davy is the prominent crater Alphonsus.

Buch is an old, worn crater that is located in the rugged southern highlands of the Moon. It was named after German geologist Leopold von Buch. It lies to the northeast of the large crater Maurolycus, and the comparably sized crater Büsching is attached to the northeast rim.

De Sitter is a lunar impact crater that is located near the northern limb of the Moon, to the north of the Baillaud–Euctemon crater pair. Due to its location, this crater appears very foreshortened when viewed from the Earth, limiting the detail that can be viewed. The crater also receives sunlight at a low angle, when it is on the sunlit side.

References

↑ Ambrose, W.A. "ORIGIN, DISTRIBUTION, AND CHRONOSTRATIGRAPHY OF ASYMMETRIC SECONDARY CRATERS ASSOCIATED WITH NEARSIDE LUNAR BASINS" (PDF). Bureau of Economic Geology. University of Texas at Austin, TX. Retrieved 25 September 2013.
↑ The geologic history of the Moon. USGS Professional Paper 1348. By Don E. Wilhelms, John F. McCauley, and Newell J. Trask. U.S. Government Printing Office, Washington: 1987. Table 9-4.
↑ Alphonsus, Gazetteer of Planetary Nomenclature, International Astronomical Union (IAU) Working Group for Planetary System Nomenclature (WGPSN)
↑ EXPLORING SPACE WITH A CAMERA, Section 2, To The Moon and Beyond, NASA Special Publication 168 (SP-168)
↑ To a Rocky Moon: A Geologist's History of Lunar Exploration. Don E. Wilhelms, University of Arizona Press (1993). ISBN 978-0816510658 Chapter 16.
↑ To a Rocky Moon: A Geologist's History of Lunar Exploration. Don E. Wilhelms, University of Arizona Press (1993). ISBN 978-0816510658 Chapter 17.
↑ Dinsmore (1957), 69: 158
↑ Oepik, E.J. (January 1968). "Cratering and the moon's surface". Armagh Observatory. Department of Physics and Astronomy, University of Maryland. hdl:2060/19690007782.
↑ Dinsmore (1957), 71: 46
↑ "Alphonsus (crater)". Gazetteer of Planetary Nomenclature. USGS Astrogeology Research Program.
↑ Ewen A. Whitaker, Mapping and Naming the Moon (Cambridge University Press, 1999), p.210.
↑ Ewen A. Whitaker, Mapping and Naming the Moon (Cambridge University Press, 1999), p. 198.
↑ Ewen A. Whitaker, Mapping and Naming the Moon (Cambridge University Press, 1999), p. 205.

Andersson, L. E.; Whitaker, E. A. (1982). NASA Catalogue of Lunar Nomenclature. NASA RP-1097.
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McDowell, Jonathan (July 15, 2007). "Lunar Nomenclature". Jonathan's Space Report. Retrieved 2007-10-24.
Menzel, D. H.; Minnaert, M.; Levin, B.; Dollfus, A.; Bell, B. (1971). "Report on Lunar Nomenclature by the Working Group of Commission 17 of the IAU". Space Science Reviews. 12 (2): 136–186. Bibcode:1971SSRv...12..136M. doi:10.1007/BF00171763. S2CID 122125855.
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External links

Alphonsus at The Moon Wiki Archived 2015-11-09 at the Wayback Machine
Rimae Alphonsus at The Moon Wiki
Alphonsus crater mantled floor fracture, from LROC
Lunar Orbiter map and photo of Alphonsus

v t e Craters on the Moon: C–F
C	C. Herschel C. Mayer Cabannes Cabeus Cailleux Cai Lun Cajal Cajori Calippus Cameron Campanus Campbell Cannizzaro Cannon Cantor Capella Capuanus Cardanus Carlini Carlos Carmichael Carnot Carol Carpenter Carrel Carrillo Carrington Cartan Carver Casatus Cassegrain Cassini Catalán Catharina Cauchy Cavalerius Cavendish Caventou Cayley Celsius Censorinus Cepheus Chacornac Chadwick Chaffee Challis Chalonge Chamberlin Champollion Chandler Chang Heng Chang-Ngo Chant Chaplygin Chapman Chappe Chappell Charles Charlier Chaucer Chauvenet Chawla Chebyshev Chernyshev Chevallier Ching-Te Chladni Chrétien Cichus Clairaut Clark Clausius Clavius Cleomedes Cleostratus Clerke Coblentz Cockcroft Collins Colombo Compton Comrie Comstock Condon Condorcet Congreve Conon Cook Cooper Copernicus Cori Coriolis Couder Coulomb Courtney Cremona Crile Crocco Crommelin Crookes Crozier Crüger Ctesibius Curie Curtis Curtius Cusanus Cuvier Cyrano Cyrillus Cysatus
D	D. Brown da Vinci Daedalus Dag Daguerre Dale d'Alembert Dalton Daly Damoiseau Dandelion Daniell Danjon Dante Darney D'Arrest D'Arsonval Darwin Das Daubrée Davisson Davy Dawes Dawson De Forest de Gasparis de Gerlache De La Rue De Moraes De Morgan De Roy De Sitter De Vico De Vries Debes Debus Debye Dechen Delambre Delaunay Delia Delisle Dellinger Delmotte Delporte Deluc Dembowski Democritus Demonax Denning Desargues Descartes Deseilligny Deslandres Deutsch Dewar Diana Diderot Dionysius Diophantus Dirichlet Dobrovolʹskiy Doerfel Dollond Donati Donna Donner Doppelmayer Doppler Douglass Dove Draper Drebbel Dreyer Drude Dryden Drygalski Dubyago Dufay Dugan Dunér Dunthorne Dyson Dziewulski
E	Eckert Eddington Edison Edith Egede Ehrlich Eichstadt Eijkman Eimmart Einstein Einthoven Elger Ellerman Ellison Elmer Elvey Emden Encke Endymion Engelʹgardt Eötvös Epigenes Epimenides Eratosthenes Erlanger Erro Esclangon Esnault-Pelterie Espin Euclides Euctemon Eudoxus Euler Evans Evdokimov Evershed Ewen
F	Fabbroni Fabricius Fabry Fahrenheit Fairouz Faraday Faustini Fauth Faye Fechner Fedorov Felix Fényi Feoktistov Fermat Fermi Fernelius Fersman Fesenkov Feuillée Fibiger Finsch Finsen Firmicus Firsov Fischer Fitzgerald Fizeau Flammarion Flamsteed Fleming Florensky Florey Focas Fontana Fontenelle Foster Foucault Fourier Fowler Fox Fra Mauro Fracastorius Franck Franklin Franz Fraunhofer Fredholm Freud Freundlich Fridman Froelich Frost Fryxell Furnerius