Mare Marginis (

Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

for 'Sea of the Edge'); ) is a

lunar mare The lunar maria ( ; mare ) are large, dark, basaltic plains on Earth's Moon, formed by lava flowing into ancient impact basins. They are less reflective than the "highlands" as a result of their iron-rich composition, and hence appear dark to ...

that lies on the very edge of the lunar nearside. The selenographic

coordinate In geometry, a coordinate system is a system that uses one or more numbers, or coordinates, to uniquely determine and standardize the position of the points or other geometric elements on a manifold such as Euclidean space. The coordinates are ...

s of this feature are 13.3° N, 86.1° E, and the diameter is 358 km. This mare differs from most of the nearside maria; it has an irregular outline and it appears to be fairly thin. It has small circular and elongated features in the mare plains that probably mark

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 ...

s buried by less than 1000 to 1700 feet (300 to 500 m) of

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 ...

. Further, Mare Marginis is not centered on any clear, large impact basin. Thus, Mare Marginis seems to mark a low-lying region of the highlands where mare lavas were just able to reach the surface. Several large mare-floored craters also occur nearby. In these craters, the crater floors lie below the surrounding highland surface. Thus, they mark sites around Mare Marginis where lavas were close to the lunar surface. The major crater to the north of Marginis is

Al-Biruni Abu Rayhan Muhammad ibn Ahmad al-Biruni (; ; 973after 1050), known as al-Biruni, was a Khwarazmian Iranian scholar and polymath during the Islamic Golden Age. He has been called variously "Father of Comparative Religion", "Father of modern ...

, with

Ibn Yunus Abu al-Hasan 'Ali ibn Abi al-Said 'Abd al-Rahman ibn Ahmad ibn Yunus ibn Abd al-'Ala al-Sadafi al-Misri (Egyptian Arabic: ابن يونس; c. 950 – 1009) was an important Arabs, Arab Egyptians, Egyptian astronomer and Islamic mathematics, math ...

to the southeast and Goddard to the northwest. The surface of this mare displays some lunar swirls; higher

albedo Albedo ( ; ) is the fraction of sunlight that is Diffuse reflection, diffusely reflected by a body. It is measured on a scale from 0 (corresponding to a black body that absorbs all incident radiation) to 1 (corresponding to a body that reflects ...

deposits that are similar to the Reiner Gamma feature on the Oceanus Procellarum. This feature is associated with a relatively strong

magnetic field A magnetic field (sometimes called B-field) is a physical field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular ...

. It is also located at the antipode of the Mare Orientale impact basin, and may be associated with the formation of that feature. Other possible explanations for the formation include a

comet A comet is an icy, small Solar System body that warms and begins to release gases when passing close to the Sun, a process called outgassing. This produces an extended, gravitationally unbound atmosphere or Coma (cometary), coma surrounding ...

ary impact, venting of volcanic gases, or just normal surface markings that are shielded from space weathering due to the magnetic field. But the exact cause of albedo features such as this are not completely understood.

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Image:Mare Marginis 4165 h3.jpg, Oblique

Lunar Orbiter 4 Lunar Orbiter 4 was a robotic U.S. spacecraft, part of the Lunar Orbiter program, Lunar Orbiter Program, designed to orbit the Moon, after the three previous orbiters had completed the required needs for Project Apollo, Apollo mapping and site s ...

image of the western portion of Mare Marginis. The large crater to the south is

Neper The neper (symbol: Np) is a logarithmic unit for ratios of measurements of physical field and power quantities, such as gain and loss of electronic signals. The unit's name is derived from the name of John Napier, the inventor of logarithms. ...

. Image:Mare Marginis AS16-P-5676.jpg, View from

Apollo 16 Apollo 16 (April 1627, 1972) was the tenth human spaceflight, crewed mission in the United States Apollo program, Apollo space program, administered by NASA, and the fifth and penultimate to Moon landing, land on the Moon. It was the second o ...

, with north in upper left. Image:Mare Marginis AS17-M-0895-0900-0905.jpg, These are three views of Mare Marginis, taken by the mapping camera of the

Apollo 17 Apollo 17 (December 7–19, 1972) was the eleventh and final mission of NASA's Apollo program, the sixth and most recent time humans have set foot on the Moon. Commander Gene Cernan and Lunar Module Pilot Harrison Schmitt walked on the Moon, ...

mission in 1972, facing north-northeast from an average altitude of . At the right is the east side of Mare Marginis, with the craters Jansky, Jansky F, and the elongated Jansky D in the foreground, and the eastern mare is in the upper left. The center photo shows the central mare with the prominent crater Goddard surrounded by light materials, the crater

immediately to its east, Goddard C to the west, half of the large crater

in the foreground, and the crater Hubble far to the north near the horizon. The swirls of light material in the mare, thought to be caused by magnetic fields, are visible in this photo. The left photo shows the western mare (more easily visible from Earth), with disconnected "lakes" of basalt, and the crater

Cannon A cannon is a large-caliber gun classified as a type of artillery, which usually launches a projectile using explosive chemical propellant. Gunpowder ("black powder") was the primary propellant before the invention of smokeless powder during th ...

. These photos were taken within minutes of each other as the Command Module ''America'' orbited the Moon.

References

* Paul D. Spudis, ''The Once and Future Moon'', Smithsonian Institution Press,

1996 1996 was designated as: * International Year for the Eradication of Poverty Events January * January 8 – A Zairean cargo plane crashes into a crowded market in the center of the capital city of the Democratic Republic of the Congo ...

, . {{Lunar maria Marginis

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See also

References