Alphonsus (crater)
Encyclopedia
Alphonsus is an ancient impact crater
on the Moon
that dates from the immediate post-Nectarian
era. 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. The surface is broken and irregular along this boundary. The outer walls are slightly distorted and possess a somewhat hexagonal form. To the northwest is the smaller Alpetragius
.
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 rille
s and contains three 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
.
Alphonsus was one of the primary alternative landing sites considered for both the Apollo 16
and the Apollo 17
missions. The Ranger 9
probe impacted in Alphonsus, a short distance to the northeast of the central peak. Harold Urey
said of a Ranger IX close-up photograph of Alphonsus:
, 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.
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. 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.
. These are listed in the table below.
Impact crater
In the broadest sense, the term impact crater can be applied to any depression, natural or manmade, resulting from the high velocity impact of a projectile with a larger body...
on the Moon
Moon
The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...
that dates from the immediate post-Nectarian
Nectarian
The Nectarian Period of the lunar geologic timescale runs from 3920 million years ago to 3850 million years ago. It is the period during which the Nectaris Basin and other major basins were formed by large impact events...
era. It is located on the lunar highlands on the eastern end of Mare Nubium
Mare Nubium
Mare Nubium 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. The actual basin is believed to be of Pre-Nectarian system, with the surrounding basin material being of the Lower Imbrian epoch. The mare material is of the...
, west of the Imbrian Highlands, and slightly overlaps the crater Ptolemaeus
Ptolemaeus (lunar crater)
Ptolemaeus is an ancient lunar impact crater close to the center of the near side. To the south-southeast Ptolemaeus is joined to the rim of the crater Alphonsus by a section of rugged, irregular terrain, and these form a prominent chain with Arzachel to the south...
to the north. The surface is broken and irregular along this boundary. The outer walls are slightly distorted and possess a somewhat hexagonal form. To the northwest is the smaller Alpetragius
Alpetragius (crater)
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....
.
A low ridge system of deposited ejecta bisects the crater floor, and includes the steep central peak designated Alphonsus Alpha (α). This pyramid
Pyramid
A pyramid is a structure whose outer surfaces are triangular and converge at a single point. The base of a pyramid can be trilateral, quadrilateral, or any polygon shape, meaning that a pyramid has at least three triangular surfaces...
-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
Anorthosite is a phaneritic, intrusive igneous rock characterized by a predominance of plagioclase feldspar , and a minimal mafic component...
like the lunar highlands.
The floor is fractured by an elaborate system of rille
Rille
Rille is typically used to describe any of the long, narrow depressions in the lunar surface that resemble channels. Typically a rille can be up to several kilometers wide and hundreds of kilometers in length...
s and contains three smaller craters surrounded by a symmetric darker halo. These dark-halo craters are cinder cone
Volcanic cone
Volcanic cones are among the simplest volcanic formations. They are built by ejecta from a volcanic vent, piling up around the vent in the shape of a cone with a central crater. Volcanic cones are of different types, depending upon the nature and size of the fragments ejected during the eruption...
-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
Regolith
Regolith is a layer of loose, heterogeneous material covering solid rock. It includes dust, soil, broken rock, and other related materials and is present on Earth, the Moon, some asteroids, and other terrestrial planets and moons.-Etymology:...
.
Alphonsus was one of the primary alternative landing sites considered for both the Apollo 16
Apollo 16
Young and Duke served as the backup crew for Apollo 13; Mattingly was slated to be the Apollo 13 command module pilot until being pulled from the mission due to his exposure to rubella through Duke.-Backup crew:...
and the Apollo 17
Apollo 17
Apollo 17 was the eleventh and final manned mission in the American Apollo space program. Launched at 12:33 a.m. EST on December 7, 1972, with a three-member crew consisting of Commander Eugene Cernan, Command Module Pilot Ronald Evans, and Lunar Module Pilot Harrison Schmitt, Apollo 17 remains the...
missions. The Ranger 9
Ranger 9
Ranger 9 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 six television vidicon cameras, 2 wide angle and 4 narrow angle to accomplish these objectives...
probe impacted in Alphonsus, a short distance to the northeast of the central peak. Harold Urey
Harold Urey
Harold Clayton Urey was an American physical chemist whose pioneering work on isotopes earned him the Nobel Prize in Chemistry in 1934...
said of a Ranger IX close-up photograph of Alphonsus:
Transient lunar phenomena
Alphonsus is one of the sites noted for transient lunar phenomenaTransient lunar phenomenon
A transient lunar phenomenon , or lunar transient phenomenon , is a short-lived light, color, or change in appearance on the lunar surface....
, as glowing red-hued clouds have been reported emanating from the crater. On October 26, 1956, the lunar astronomer
Astronomer
An astronomer is a scientist who studies celestial bodies such as planets, stars and galaxies.Historically, astronomy was more concerned with the classification and description of phenomena in the sky, while astrophysics attempted to explain these phenomena and the differences between them using...
Dinsmore Alter
Dinsmore Alter
Dinsmore Alter was an American astronomer and meteorologist.He was born in Colfax, Washington, and attended college at Westminster College in Pennsylvania. After graduating in 1909 with a B.S. degree, he married Ada McClelland...
noted some blurring of the rilles on the floor of Alphonsus in the photographs he took in violet
Violet (color)
As the name of a color, violet is synonymous with a bluish purple, when the word "purple" is used in the common English language sense of any color between blue and red, not including either blue or red...
light. The same blurring did not occur in the infrared
Infrared
Infrared light is electromagnetic radiation with a wavelength longer than that of visible light, measured from the nominal edge of visible red light at 0.74 micrometres , and extending conventionally to 300 µm...
photographs he took at the same time. However, few professional astronomers found this evidence of volcanic activity on the Moon very convincing.
One astronomer who was intrigued by Alter's observations was Nikolai A. Kozyrev, from the Soviet Union
Soviet Union
The Soviet Union , officially the Union of Soviet Socialist Republics , was a constitutionally socialist state that existed in Eurasia between 1922 and 1991....
. 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
Carbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...
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.
Interior craters
Five tiny craters in the northeastern part of Alphonsus' interior floor have been assigned names by the IAUInternational Astronomical Union
The International Astronomical Union IAU is a collection of professional astronomers, at the Ph.D. level and beyond, active in professional research and education in astronomy...
. These are listed in the table below.
| Crater | Coordinates | Diameter | Name source |
|---|---|---|---|
| Chang-Ngo | 12.7°S 2.1°W | 3 km | Chinese China Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture... feminine name1 |
| José | 12.7°S 1.6°W | 2 km | Spanish Spanish language Spanish , also known as Castilian , is a Romance language in the Ibero-Romance group that evolved from several languages and dialects in central-northern Iberia around the 9th century and gradually spread with the expansion of the Kingdom of Castile into central and southern Iberia during the... masculine name |
| Monira | 12.6°S 1.7°W | 2 km | Arabic Arabic language Arabic is a name applied to the descendants of the Classical Arabic language of the 6th century AD, used most prominently in the Quran, the Islamic Holy Book... feminine name |
| Ravi | 12.5°S 1.9°W | 2.5 km | Indian masculine name |
| Soraya | 12.9°S 1.6°W | 2 km | Persian Persian language Persian is an Iranian language within the Indo-Iranian branch of the Indo-European languages. It is primarily spoken in Iran, Afghanistan, Tajikistan and countries which historically came under Persian influence... feminine name |
- See also Chang'eChang'e (mythology)Chang'e, Ch'ang-O, Chang-Ngo or Sheung Ngo , originally known as Heng'e or Heng-O , is the Chinese goddess of the Moon. Unlike many lunar deities in other cultures who personify the Moon, Chang'e only lives on the Moon...
, the Chinese goddess.
Satellite craters
By convention these features are identified on lunar maps by placing the letter on the side of the crater mid-point 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 |