Mare Imbrium (

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

''imbrium'', the "Sea of Showers" or "Sea of Rains", "Sea of Tears") is a vast

lava plain Lava fields are large, mostly flat areas of surface or subaquatic lava flows. Such features are generally composed of highly fluid basalt lava, and can extend for tens or hundreds of miles across the underlying terrain. Morphology and stru ...

within the Imbrium Basin 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 ...

and is one of the larger craters in the Solar System. The Imbrium Basin formed from the collision of a proto-planet during the

Late Heavy Bombardment The Late Heavy Bombardment (LHB), or lunar cataclysm, is a hypothesized event thought to have occurred approximately 4.1 to 3.8 billion years (Ga) ago, at a time corresponding to the Neohadean and Eoarchean eras on Earth. According to the hypoth ...

. Basaltic

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 moon onto its surface. Lava may be erupted at a volcano or through a fracture in the crust, on land or un ...

later flooded the giant crater to form the flat volcanic plain seen today. The basin's age has been estimated using uranium–lead dating methods to approximately 3.9 billion years ago, and the diameter of the impactor has been estimated to be 250 ± 25 km. The Moon's maria (plural of

mare A mare is an adult female horse or other equine. In most cases, a mare is a female horse over the age of three, and a filly is a female horse three and younger. In Thoroughbred horse racing, a mare is defined as a female horse more than four ...

) have fewer features than other areas of the Moon because molten lava pooled in the craters and formed a relatively smooth surface. Mare Imbrium is not as flat as it was originally thought, because later events have altered its surface.

Origin

Mare Imbrium formed when a

proto-planet A protoplanet is a large planetary embryo that originated within a protoplanetary disc and has undergone internal melting to produce a differentiated interior. Protoplanets are thought to form out of kilometer-sized planetesimals that gravitationa ...

from the asteroid belt collided with the moon during the

. The impact is dated to approximately 3922 ± 12 million years ago, based on

radiometric dating Radiometric dating, radioactive dating or radioisotope dating is a technique which is used to date materials such as rocks or carbon, in which trace radioactive impurities were selectively incorporated when they were formed. The method compares t ...

techniques. Ejecta from the impact cover large areas of the near side of the moon.

Characteristics

With a diameter of 1145 km, Mare Imbrium is second only to

Oceanus Procellarum Oceanus Procellarum ( la, Ōceanus procellārum, lit=Ocean of Storms) is a vast lunar mare on the western edge of the near side of the Moon. It is the only one of the lunar maria to be called an "Oceanus" (ocean), due to its size: Oceanus Proc ...

in size among the maria, and it is the largest mare associated with an impact basin. The Imbrium Basin is surrounded by three concentric rings of mountains, uplifted by the colossal impact event that excavated it. The outermost ring of mountains has a diameter of 1300 km and is divided into several different ranges; the

Montes Carpatus Montes Carpatus is a mountain range that forms the southern edge of the Mare Imbrium on the Moon. The selenographic coordinates of this range are 14.5° N, 24.4° W, and the formation has an overall diameter of . They were named by astronomer ...

to the south, the

Montes Apenninus Montes Apenninus are a rugged mountain range on the northern part of the Moon's near side. They are named after the Apennine Mountains in Italy. With their formation dating back about 3.9 billion years, Montes Apenninus are fairly old. Descri ...

to the southeast, and the

Montes Caucasus Montes Caucasus is a rugged range of mountains in the northeastern part of the Moon. It begins at a gap of level surface that joins the Mare Imbrium to the west with the Mare Serenitatis to the east, and extends in an irregular band to the n ...

to the east. The ring mountains are not as well developed to the north and west, and it appears they were simply not raised as high in these regions by the Imbrium impact. The middle ring of mountains forms the

Montes Alpes Montes Alpes is a mountain range in the northern part of the Moon's near side. It was named after the Alps in Europe; the name was confirmed by the International Astronomical Union in 1935. It lies between the selenographic coordinates latitudes ...

and the mountainous regions near the craters

Archimedes Archimedes of Syracuse (;; ) was a Greek mathematician, physicist, engineer, astronomer, and inventor from the ancient city of Syracuse in Sicily. Although few details of his life are known, he is regarded as one of the leading scientists ...

and

Plato Plato ( ; grc-gre, Πλάτων ; 428/427 or 424/423 – 348/347 BC) was a Greek philosopher born in Athens during the Classical period in Ancient Greece. He founded the Platonist school of thought and the Academy, the first institution ...

. The innermost ring, with a diameter of 600 km, has been largely buried under the mare's basalt leaving only low hills protruding through the mare plains and mare ridges forming a roughly circular pattern. The outer ring of mountains rise roughly 7 km above the surface of Mare Imbrium. The Mare material is thought to be about 5 km deep, giving the Imbrium Basin a total depth of 12 km; it is thought that the original crater left by the Imbrium impact was as much as 100 km deep, but that the floor of the basin bounced back upwards immediately afterwards. Imbrium sculpture Ukert crater 3085 med

Surrounding the Imbrium Basin is a region blanketed by ejecta from the impact, extending roughly 800 km outward. Also encircling the basin is a pattern of radial grooves called the "Imbrium Sculpture", which have been interpreted as furrows cut in the Moon's surface by large projectiles blasted out of the basin at low angles, causing them to skim across the lunar surface ploughing out these features. The sculpture pattern was first identified by Grove Karl Gilbert in 1893. Furthermore, a Moon-wide pattern of faults which run both radial to and concentric to the Imbrium basin were thought to have been formed by the Imbrium impact; the event literally shattered the Moon's entire

lithosphere A lithosphere () is the rigid, outermost rocky shell of a terrestrial planet or natural satellite. On Earth, it is composed of the crust (geology), crust and the portion of the upper mantle (geology), mantle that behaves elastically on time sca ...

. At the region of the Moon's surface exactly opposite Imbrium Basin, there is a region of chaotic terrain (the crater Van de Graaff) which is thought to have been formed when the seismic waves of the impact were focused there after travelling through the Moon's interior. Mare Imbrium is about wide. A mass concentration (mascon), or gravitational high, was identified in the center of Mare Imbrium from Doppler tracking of the five

Lunar Orbiter The Lunar Orbiter program was a series of five uncrewed lunar orbiter missions launched by the United States from 1966 through 1967. Intended to help select Apollo landing sites by mapping the Moon's surface, they provided the first photographs ...

spacecraft in 1968. The Imbrium mascon is the largest on the moon. It was confirmed and mapped at higher resolution with later orbiters such as

Lunar Prospector ''Lunar Prospector'' was the third mission selected by NASA for full development and construction as part of the Discovery Program. At a cost of $62.8 million, the 19-month mission was designed for a low polar orbit investigation of the Moon, ...

and

GRAIL The Gravity Recovery and Interior Laboratory (GRAIL) was an American lunar science mission in NASA's Discovery Program which used high-quality gravitational field mapping of the Moon to determine its interior structure. The two small spacecraf ...

. File:Imbrium basin topo.jpg, Shaded Relief map File:Imbrium basin GRAIL gravity.jpg, Gravity map based on

Names

Like most of the other maria on the Moon, Mare Imbrium was named by

Giovanni Riccioli Giovanni Battista Riccioli, SJ (17 April 1598 – 25 June 1671) was an Italian astronomer and a Catholic priest in the Jesuit order. He is known, among other things, for his experiments with pendulums and with falling bodies, for his discussion ...

, whose 1651 nomenclature system has become standardized. The earliest known name for the mare may be "The Shrine of

Hecate Hecate or Hekate, , ; grc-dor, Ἑκάτᾱ, Hekátā, ; la, Hecatē or . is a goddess in ancient Greek religion and mythology, most often shown holding a pair of torches, a key, snakes, or accompanied by dogs, and in later periods depict ...

Plutarch Plutarch (; grc-gre, Πλούταρχος, ''Ploútarchos''; ; – after AD 119) was a Greek Middle Platonist philosopher, historian, biographer, essayist, and priest at the Temple of Apollo in Delphi. He is known primarily for his ''P ...

records that the

Ancient Greeks Ancient Greece ( el, Ἑλλάς, Hellás) was a northeastern Mediterranean civilization, existing from the Greek Dark Ages of the 12th–9th centuries BC to the end of classical antiquity ( AD 600), that comprised a loose collection of cult ...

gave this name to the largest of the "hollows and deeps" on the Moon, believing it to be the place where the souls of the deceased were tormented. Ewen A. Whitaker argues that this likely refers to Mare Imbrium, "the largest regular-shaped dark area unbroken by bright patches" that can be seen with the naked eye. Around 1600, William Gilbert made a map of the Moon that names Mare Imbrium "Regio Magna Orientalis" (the Large Eastern Region). Michael van Langren's 1645 map named it "Mare Austriacum" (the Austrian Sea).

Observation and exploration

Mare Imbrium is visible to the

naked eye Naked eye, also called bare eye or unaided eye, is the practice of engaging in visual perception unaided by a magnifying, light-collecting optical instrument, such as a telescope or microscope, or eye protection. Vision corrected to normal ...

from Earth. In the traditional '

Man in the Moon In many cultures, several pareidolic images of a human face, head or body are recognized in the disc of the full moon; they are generally known as the Man in the Moon. The images are based on the appearance of the dark areas (known as lunar ma ...

' image seen on the Moon in Western folklore, Mare Imbrium forms the man's right eye.

Luna 17

On 17 November 1970 at 03:47 Universal Time, the Soviet spacecraft

Luna 17 ''LOK Luna 17'' (Ye-8 series) was an unmanned space mission of the Luna program, also called ''Lunik 17''. It deployed the first robotic rover onto the surface of the Moon. Launch ''Luna 17'' was launched from an Earth parking orbit towards ...

made a soft landing in the mare, at latitude 38.28 N, and longitude 35.00 W. Luna 17 carried

Lunokhod 1 ''Lunokhod 1'' ( Russian: Луноход-1 ("Moonwalker 1"), also known as Аппарат 8ЕЛ № 203 ("Device 8EL No. 203")) was the first of two robotic lunar rovers landed on the Moon by the Soviet Union as part of its Lunokhod program. The ...

, the first

rover Rover may refer to: People * Constance Rover (1910–2005), English historian * Jolanda de Rover (born 1963), Dutch swimmer * Rover Thomas (c. 1920–1998), Indigenous Australian artist Places * Rover, Arkansas, US * Rover, Missouri, US ...

to be deployed on the Moon. Lunokhod 1, a remote-controlled rover, was successfully deployed and undertook a mission lasting several months.

Apollo 15

In 1971, the crewed

Apollo 15 Apollo 15 (July 26August 7, 1971) was the ninth crewed mission in the United States' Apollo program and the fourth to Moon landing, land on the Moon. It was the first List of Apollo missions#Alphabetical mission types, J mission, with a ...

mission landed in the southeastern region of Mare Imbrium, between

Hadley Rille Hadley may refer to: Places Canada * Hadley Bay, on the north of Victoria Island, Nunavut England * Hadley, London, a former civil parish within Barnet Urban District from 1894 to 1965 * Hadley, Shropshire, part of the new town of Telford, ...

and the

Apennine Mountains The Apennines or Apennine Mountains (; grc-gre, links=no, Ἀπέννινα ὄρη or Ἀπέννινον ὄρος; la, Appenninus or – a singular with plural meaning;''Apenninus'' (Greek or ) has the form of an adjective, which wou ...

. Commander

David Scott David Randolph Scott (born June 6, 1932) is an American retired test pilot and NASA astronaut who was the seventh person to walk on the Moon. Selected as part of the third group of astronauts in 1963, Scott flew to space three times and c ...

and Lunar Module Pilot

James Irwin James Benson Irwin (March 17, 1930 – August 8, 1991) was an American astronaut, aeronautical engineer, test pilot, and a United States Air Force pilot. He served as Apollo Lunar Module pilot for Apollo 15, the fourth human lunar landi ...

spent three days on the surface of the Moon, including 18½ hours outside the spacecraft on lunar extra-vehicular activity. Command Module Pilot Alfred Worden remained in orbit and acquired hundreds of high-resolution photographs of Mare Imbrium (and other regions of the moon) as well as other types of scientific data. The crew on the surface explored the area using the first

lunar rover A lunar rover or Moon rover is a space exploration vehicle designed to move across the surface of the Moon. The Apollo Program's Lunar Roving Vehicle was driven on the Moon by members of three American crews, Apollo 15, 16, and 17. Other rov ...

and returned to Earth with of lunar surface material. Samples were collected from Mons Hadley Delta, believed to be a fault block of pre-Imbrian ( Nectarian or

Pre-Nectarian The pre-Nectarian period of the lunar geologic timescale runs from 4.533 billion years ago (the time of the initial formation of the Moon) to 3.920 billion years ago, when the Nectaris Basin was formed by a large impact. It is followed by the Necta ...

) lunar crust, including the "

Genesis Rock The Genesis Rock (sample 15415) is a sample of Moon rock retrieved by Apollo 15 astronauts James Irwin and David Scott in 1971 during the second lunar EVA, at Spur crater. With a mass of , it is currently stored at the Lunar Sample Laborato ...

." This was also the only Apollo mission to visit a lunar rille, and to observe outcrops of lunar bedrock visible in the rille wall.

2013 Impact

On 17 March 2013, an object hit the lunar surface in Mare Imbrium and exploded in a flash of

apparent magnitude Apparent magnitude () is a measure of the brightness of a star or other astronomical object observed from Earth. An object's apparent magnitude depends on its intrinsic luminosity, its distance from Earth, and any extinction of the object's li ...

4. The resulting crater was 18 meters wide. This was the brightest impact recorded since NASA's lunar impact team began monitoring in 2005.

Chinese lander

Chang'e 3 landed on 14 December 2013 on Mare Imbrium, about 40 km south of the 6 km diameter ''Laplace F'' crater, at 44.1260°N 19.5014°W. The lander deployed the Yutu rover 7 hours and 24 minutes later. Chang'e 3 mission attempted to perform the first direct measurement of the structure and depth of the

lunar soil Lunar soil is the fine fraction of the regolith found on the surface of the Moon. Its properties can differ significantly from those of terrestrial soil. The physical properties of lunar soil are primarily the result of mechanical disinteg ...

down to a depth of , and investigate the lunar crust structure down to several hundred meters deep. The rover's ground penetrating radar found evidence of at least nine distinct rock layers, indicating that the area had surprisingly complex geological processes and is compositionally distinct from the Apollo and Luna landing sites.

References

External links

*
Mare Imbrium at The Moon Wiki
* – one of the prominent features of the photo includes Mare Imbrium {{Lunar maria Imbrium, Mare