![Ranger7 PIA02975](https://upload.wikimedia.org/wikipedia/commons/5/5e/Ranger7_PIA02975.jpg)
Alphonsus is an ancient
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 ...
on the
Moon
The Moon is Earth's only natural satellite. It is the fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth (comparable to the width of ...
that dates from the pre-Nectarian era. It is located on the lunar highlands on the eastern end 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 ha ...
, west of the
Imbrian Highlands, and slightly overlaps the crater
Ptolemaeus
Claudius Ptolemy (; grc-gre, Πτολεμαῖος, ; la, Claudius Ptolemaeus; AD) was a mathematician, astronomer, astrologer, geographer, and music theorist, who wrote about a dozen scientific treatises, three of which were of importanc ...
to the north. To the southwest is the smaller
Alpetragius.
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
A pyramid (from el, πυραμίς ') is a structure whose outer surfaces are triangular and converge to a single step at the top, making the shape roughly a pyramid in the geometric sense. The base of a pyramid can be trilateral, quadrilat ...
-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
Anorthosite () is a phaneritic, intrusive igneous rock characterized by its composition: mostly plagioclase feldspar (90–100%), with a minimal mafic component (0–10%). Pyroxene, ilmenite, magnetite, and olivine are the mafic minerals most c ...
like the lunar highlands.
The floor is fractured by an elaborate system of
rille
Rille (German for 'groove') is typically used to describe any of the long, narrow depressions in the surface of the Moon that resemble channels. The Latin term is ''rima'', plural ''rimae''. Typically, a rille can be several kilometers wid ...
s and contains four or five smaller craters surrounded by a symmetric darker halo. These dark-halo craters are
cinder cone
A cinder cone (or scoria cone) is a steep conical hill of loose pyroclastic fragments, such as volcanic clinkers, volcanic ash, or scoria that has been built around a volcanic vent. The pyroclastic fragments are formed by explosive eruptions o ...
-shaped and are believed by some to be
volcanic
A volcano is a rupture 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 found where tectonic plates a ...
in origin, although others think they were caused by impacts that excavated darker mare material from underneath the lighter lunar
regolith
Regolith () is a blanket of unconsolidated, loose, heterogeneous superficial deposits covering solid rock. It includes dust, broken rocks, and other related materials and is present on Earth, the Moon, Mars, some asteroids, and other terrestria ...
.
Exploration
The
Ranger 9
Ranger 9 was a Lunar probe, launched in 1965 by NASA. It was designed to achieve a lunar impact trajectory and to transmit high-resolution photographs of the lunar surface during the final minutes of flight up to impact. The spacecraft carried s ...
probe impacted in Alphonsus, a short distance to the northeast of the central peak.
Harold Urey
Harold Clayton Urey ( ; April 29, 1893 – January 5, 1981) was an American physical chemist whose pioneering work on isotopes earned him the Nobel Prize in Chemistry in 1934 for the discovery of deuterium. He played a significant role in the d ...
said of a close-up photograph of Alphonsus:
Alphonsus was one of the primary alternative landing sites considered for both the
Apollo 16
Apollo 16 (April 1627, 1972) was the tenth crewed mission in the United States Apollo space program, administered by NASA, and the fifth and penultimate to land on the Moon. It was the second of Apollo's " J missions", with an extended sta ...
and the
Apollo 17
Apollo 17 (December 7–19, 1972) was the final mission of NASA's Apollo program, the most recent time humans have set foot on the Moon or traveled beyond low Earth orbit. Commander Gene Cernan and Lunar Module Pilot Harrison Schmitt walked on ...
missions.
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
An astronomer is a scientist in the field of astronomy who focuses their studies on a specific question or field outside the scope of Earth. They observe astronomical objects such as stars, planets, natural satellite, moons, comets and galaxy, g ...
Dinsmore Alter
Dinsmore Alter (March 28, 1888 – September 20, 1968) was an American astronomer, meteorologist, and United States Army officer. He is known for his work with the Griffith Observatory and his creation of a lunar atlas.
Early life
He was born in ...
noted some blurring of the rilles on the floor of Alphonsus in the
photographs
A photograph (also known as a photo, image, or picture) is an image created by light falling on a photosensitive surface, usually photographic film or an electronic image sensor, such as a CCD or a CMOS chip. Most photographs are now created ...
he took in
violet
Violet may refer to:
Common meanings
* Violet (color), a spectral color with wavelengths shorter than blue
* One of a list of plants known as violet, particularly:
** ''Viola'' (plant), a genus of flowering plants
Places United States
* Viol ...
light. The same blurring did not occur in the
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 ...
photographs he took at the same time. However, few professional astronomers found this evidence of
volcanic
A volcano is a rupture 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 found where tectonic plates a ...
activity on the Moon very convincing.
One astronomer who was intrigued by Alter's observations was
Nikolai A. Kozyrev, from the
Soviet Union
The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, it was nominally a federal union of fifteen national ...
. In 1958 while Kozyrev was looking for volcanic phenomenon on the moon, he observed the formation of a mist-like cloud within Alphonsus. The spectrum of the area had been measured at this time, and displayed indications of
carbon
Carbon () is a chemical element with the symbol C and atomic number 6. It is nonmetallic and tetravalent
In chemistry, the valence (US spelling) or valency (British spelling) of an element is the measure of its combining capacity with o ...
matter, possibly C
2 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.
Names
Alphonsus is named after King
Alfonso X of Castile
Alfonso X (also known as the Wise, es, el Sabio; 23 November 1221 – 4 April 1284) was King of Castile, León and Galicia from 30 May 1252 until his death in 1284. During the election of 1257, a dissident faction chose him to be king of Germ ...
(known as "Alfonso the Wise"), who had an interest in astronomy. Like many of the craters on the Moon's near side, it was given its name by
Giovanni Riccioli
Giovanni Battista Riccioli, Society of Jesus, SJ (17 April 1598 – 25 June 1671) was an Italian astronomer and a Catholic church, Catholic priest in the Jesuit order. He is known, among other things, for his experiments with pendulums and with f ...
, whose 1651 nomenclature system has become standardized; Riccioli originally named it "Alphonsus Rex" ('King Alfonso'), but the 'Rex' was later dropped. 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
, house = Bourbon
, father = Louis XIII
, mother = Anne of Austria
, birth_date =
, birth_place = Château de Saint-Germain-en-Laye, Saint-Germain-en-Laye, France
, death_date =
, death_place = Palace of Versa ...
, 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''; pl, Jan Heweliusz; – 28 January 1687) was a councillor ...
called it "Mons Masicytus" after
a range of mountains in Lycia.
[Ewen A. Whitaker, ''Mapping and Naming the Moon'' (Cambridge University Press, 1999), p. 205.]
Interior craters
![Alphonsus small craters AS16-P-4661 ASU](https://upload.wikimedia.org/wikipedia/commons/d/dc/Alphonsus_small_craters_AS16-P-4661_ASU.jpg)
Five tiny craters in the northeastern part of Alphonsus' interior floor have been assigned names by the
IAU
The International Astronomical Union (IAU; french: link=yes, Union astronomique internationale, UAI) is a nongovernmental organisation with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach ...
. These are listed in the table below.
Satellite craters
![Alphonsus lunar crater map](https://upload.wikimedia.org/wikipedia/commons/0/0c/Alphonsus_lunar_crater_map.jpg)
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.
References
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Further reading
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External links
Alphonsus at The Moon WikiRimae Alphonsus at The Moon WikiAlphonsus crater mantled floor fracture from
LROC
LRoc (born James Elbert Phillips) is an American in-house songwriter and producer at Jermaine Dupri's So So Def Recordings. He has co-written and co-produced singles like Janet Jackson's " Call on Me", Monica's " Everytime Tha Beat Drop", M ...
Lunar Orbiter map and photo of Alphonsus
Other related articles
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* - one of three craters making up a ''Triad'' which includes Alphonsus
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Impact craters on the Moon
{{Craters on the Moon: C-F