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Encyclopedia > Lunar mare
Lunar nearside with major maria and craters labeled
A global albedo map of the Moon obtained from the Clementine missionThe dark regions are the lunar maria, whereas the lighter regions are the highlands. The image is a cylindrical projection, with longitude increasing left to right from -180 E to 180 E and latitude decreasing from top to bottom from 90 N to 90 S. The center of the image corresponds to the mean sub-Earth point, 0 N and 0 E.
A global albedo map of the Moon obtained from the Clementine missionThe dark regions are the lunar maria, whereas the lighter regions are the highlands. The image is a cylindrical projection, with longitude increasing left to right from -180 E to 180 E and latitude decreasing from top to bottom from 90 N to 90 S. The center of the image corresponds to the mean sub-Earth point, 0 N and 0 E.

The Lunar maria (singular: mare, IPA: /ˈmɑːreɪ/) are large, dark, basaltic plains on Earth's Moon, formed by ancient volcanic eruptions. They were dubbed maria, Latin for "seas", by early astronomers who mistook them for actual seas. They are less reflective than the "highlands" as a result of their iron-rich compositions, and hence appear dark to the naked eye. The maria cover about 16% of the lunar surface, mostly on the near-side visible from Earth. The few maria on the far-side are much smaller, residing mostly in very large craters where only a small amount of flooding occurred. The traditional nomenclature for the Moon also includes one oceanus (ocean), as well as features with the names lacus (lake), palus (marsh) and sinus (bay). The latter three are smaller than maria, but have the same nature and characteristics. Image File history File links Size of this preview: 600 × 600 pixelsFull resolution‎ (800 × 800 pixels, file size: 58 KB, MIME type: image/jpeg) copied from commons I, the creator of this work, hereby grant the permission to copy, distribute and/or modify this document under the terms of the... Image File history File links Size of this preview: 600 × 600 pixelsFull resolution‎ (800 × 800 pixels, file size: 58 KB, MIME type: image/jpeg) copied from commons I, the creator of this work, hereby grant the permission to copy, distribute and/or modify this document under the terms of the... Image File history File links Size of this preview: 800 × 400 pixelsFull resolution‎ (1,080 × 540 pixels, file size: 204 KB, MIME type: image/jpeg) File historyClick on a date/time to view the file as it appeared at that time. ... Image File history File links Size of this preview: 800 × 400 pixelsFull resolution‎ (1,080 × 540 pixels, file size: 204 KB, MIME type: image/jpeg) File historyClick on a date/time to view the file as it appeared at that time. ... Clementine was a joint space project between the Ballistic Missile Defense Organization (BMDO, previously the Strategic Defense Initiative Organization, or SDIO) and NASA. The objective of the mission was to test sensors and spacecraft components under extended exposure to the space environment and to make scientific observations of the Moon... Mercator world map Nova et Aucta Orbis Terrae Descriptio ad Usum Navigatium Emendate (1569) The Mercator projection is a cylindrical map projection presented by the Flemish geographer and cartographer Gerardus Mercator, in 1569. ... Articles with similar titles include the NATO phonetic alphabet, which has also informally been called the “International Phonetic Alphabet”. For information on how to read IPA transcriptions of English words, see IPA chart for English. ... For the cities, see Basalt, Colorado and Basalt, Idaho. ... This article is about Earth as a planet. ... This article is about Earths moon. ... For other uses, see Latin (disambiguation). ... This article is about the body of water. ...

Contents

Ages

The ages of the mare basalts have been determined both by direct radiometric dating and by the technique of crater counting. The radiometric ages range from about 3.16 to 4.2 Ga[1], whereas the youngest ages determined from crater counting are about 1.2 Ga (1 Ga = 1 billion years old)[2]. Nevertheless, the majority of mare basalts appear to have erupted between about 3 and 3.5 Ga. The few basaltic eruptions that occurred on the far side are old, whereas the youngest flows are found within Oceanus Procellarum on the nearside. While many of the basalts either erupted within, or flowed into, low lying impact basins, the largest expanse of volcanic units, Oceanus Procellarum, does not correspond to any known impact basin. Radiometric dating (often called radioactive dating) is a technique used to date materials, based on a comparison between the observed abundance of particular naturally occurring radioactive isotopes and their known decay rates. ... This article, which relates to the Moon, is a stub. ... The Ocean of Storms of the Moon. ...


Distribution of mare basalts

There are many common misconceptions concerning the spatial distribution of mare basalts.

  1. Since many mare basalts fill low-lying impact basins, it was once thought that the impact event itself somehow caused the volcanic eruption. Given that mare volcanism typically occurred about 500 million years after the impact, a causal relationship is unlikely.
  2. It is sometimes suggested that the gravity field of the Earth might preferentially allow eruptions to occur on the near side, but not far side. However, in a reference frame rotating with the Moon, the centrifugal acceleration is exactly equal and opposite to the gravitational acceleration of the Earth. There is thus no net force directed towards the Earth. The Earth tides do act to deform the shape of the Moon, but this shape is one of an elongated ellipsoid with high points at both the sub- and anti-Earth points. As an analogy, one should remember that there are two high tides per day on Earth, and not one.
  3. Since mare basaltic magmas are more dense than upper crustal anorthositic materials, basaltic eruptions might be favored at locations of low elevation where the crust is thin. However, the farside South Pole-Aitken basin contains the lowest elevations of the Moon and is yet only modestly filled by basaltic lavas. In addition, the crustal thickness beneath this basin is predicted to be much smaller than beneath Oceanus Procellarum. While crustal thickness might modulate the quantity of basaltic lavas that ultimately reach the surface, crustal thickness by itself can not be the sole factor controlling the distribution of mare basalts.[3]
  4. It is commonly suggested that there is some form of link between the synchronous rotation of the Moon about the Earth, and the mare basalts. However, gravitational torques that result in tidal despinning only arise from the moments of inertia of the body (these are directly relatable to the spherical harmonic degree-2 terms of the gravity field), and the mare basalts hardly contribute to this (see also Tidal locking). (Hemispheric structures correspond to spherical harmonic degree-1, and do not contribute to the moments of inertia.) Furthermore, tidal despinning is predicted to have occurred quickly (on the order to 10s of millions of years), whereas the majority of mare basalts erupted about 1 billion years later.

The reason that the mare basalts are predominantly located on the near-side hemisphere of the Moon is still being debated by the scientific community. Based on data obtained from the Lunar Prospector mission, it appears that a large proportion of the Moon's inventory of heat producing elements (in the form of KREEP) is located within the regions of Oceanus Procellarum and the Imbrium basin, a unique geochemical province now referred to as the Procellarum KREEP Terrane.[4][5][6] While the enhancement in heat production within the Procellarum KREEP Terrane is most certainly related to the longevity and intensity of volcanism found there, the mechanism by which KREEP became concentrated within this region is not agreed upon[7]. The near side of the Moon is the lunar hemisphere that is permanently turned towards the Earth, and as such the side which is always seen. ... Far side of the Moon. ... Centrifugal force (from Latin centrum center and fugere to flee) is a term which may refer to two different forces which are related to rotation. ... The South Pole-Aitken basin is an impact crater on Earths Moon. ... Due to synchronous rotation of their moon, the inhabitants of the central body will never be able to see its green side. ... Moment of inertia, also called mass moment of inertia and, sometimes, the angular mass, (SI unit kilogram metre squared kg m2) quantifies the rotational inertia of an object, i. ... Spherical Harmonic is a fantasy novel by Catherine Asaro which tells the story of Pharaoh Dyhianna (Dehya) Selei, ruler of the Skolian Imperialate, after the Radiance War fought by the Imperialate and their enemy Eubian Concord. ... Tidal locking makes one side of an astronomical body always face another, like the Moon facing the Earth. ... NASAs Lunar Prospector The Lunar Prospector mission was the third selected by NASA for full development and construction as part of the Discovery Program. ... KREEP stands for potassium (atomic symbol K), rare earth elements (REE), and phosphorus (P). ... The Ocean of Storms of the Moon. ... Oblique view of Mare Imbrium looking south towards Copernicus crater. ... This article, which relates to the Moon, is a stub. ...


Composition

Mare basalts are generally grouped into three series based on their major element chemistry: high-Ti basalts, low-Ti basalts, and very Low-Ti (VLT) basalts. While these groups were once thought to be distinct based on the Apollo samples, global remote sensing data from the Clementine mission now shows that there is a continuum of titanium concentrations between these end members, and that the high-titanium concentrations are the least abundant. TiO2 abundances can reach up to 15 wt.% for mare basalts, whereas most terrestrial basalts have abundances much less than 4 wt.%. Other geochemical subdivisions are based on the abundance of aluminium and potassium. Clementine was a joint space project between the Ballistic Missile Defense Organization (BMDO, previously the Strategic Defense Initiative Organization, or SDIO) and NASA. The objective of the mission was to test sensors and spacecraft components under extended exposure to the space environment and to make scientific observations of the Moon...


See also

This article is about Earths moon. ... Exploring Shorty crater during the Apollo 17 mission to the Moon. ... This is a list of maria (singular mare) on the Moon. ... Genesis Rock returned by the Apollo 15 mission. ... Selenography is the study of the surface and physical features of the Moon, especially the mapping of the features according to the Moons latitude and longitude. ...

References

Cited references

  1. ^ James Papike, Grahm Ryder, and Charles Shearer (1998). "Lunar Samples". Reviews in Mineralogy and Geochemistry 36: 5.1-5.234. 
  2. ^ H. Hiesinger, J. W. Head, U. Wolf, R. Jaumanm, and G. Neukum (2003). "Ages and stratigraphy of mare basalts in Oceanus Procellarum, Mare Numbium, Mare Cognitum, and Mare Insularum". J. Geophys. Res. 108: doi:10.1029/2002JE001985. 
  3. ^ Mark Wieczorek, Maria Zuber, and Roger Phillips (2001). "The role of magma buoyancy on the eruption of lunar basalts". Earth Planet. Sci. Lett. 185: 71-83. 
  4. ^ Mark Wieczorek and 15 coauthors (2006). "The constitution and structure of the lunar interior". Reviews in Mineralogy and Geochemistry 60: 221-364. 
  5. ^ G. Jeffrey Taylor (August 31, 2000). A New Moon for the Twenty-First Century.
  6. ^ Bradley. Jolliff, Jeffrey Gillis, Larry Haskin, Randy Korotev, and Mark Wieczorek (2000). "Major lunar crustal terranes". J. Geophys. Res.: 4197-4216. 
  7. ^ Charles Shearer and 15 coauthors (2006). "Thermal and magmatic evolution of the Moon". Reviews in Mineralogy and Geochemistry 60: 365-518. 

General references

  • Paul D. Spudis, The Once and Future Moon, Smithsonian Institution Press, 1996, ISBN 1-56098-634-4.
  • G. Jeffrey Taylor (April 30, 2006). Finding Basalt Chips from Distant Maria.
  • G. Jeffrey Taylor (December 5, 2000). Recipe for High-Titanium Lunar Magmas.
  • G. Jeffrey Taylor (June 23, 2000). The Surprising Lunar Maria.
  • Catherine Weitz (February 12, 1997). Explosive Volcanic Eruptions on the Moon.

External links


  Results from FactBites:
 
Mare - Wikipedia, the free encyclopedia (153 words)
In English, a mare (an old Germanic word) is a female horse; the word is also an etymological root of marshall (originally a 'horse servant').
Mare is an atoll in the Loyalty Islands.
Thus, the Lunar mare is an ancient basaltic lava floodplain on Earth's Moon, usually inside an impact basin.
ALS Lunar Observers Certificate List of Objects (2616 words)
Mare Imbrium: One of the youngest multi-ring basins, whose lava flooding covered most of the inner rings.
Mare ridges inside Humorum: these are circular in plan, and mark the inner ring.
Mare ridges, inside the crater, likely mark the central peaks (where subsidence was the least).
  More results at FactBites »

 
 

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