Mare Smythii (

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 "Smyth's Sea") 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 ...

located along the equator on the easternmost edge of the

Moon The Moon is Earth's only natural satellite. It Orbit of the Moon, orbits around Earth at Lunar distance, an average distance of (; about 30 times Earth diameter, Earth's diameter). The Moon rotation, rotates, with a rotation period (lunar ...

's near side, named for the 19th-century British astronomer

William Henry Smyth Admiral William Henry Smyth (21 January 1788 – 8 September 1865) was an English Royal Navy officer, hydrographer, astronomer and numismatist. He is noted for his involvement in the early history of a number of learned societies, for his hy ...

. It is one of only two lunar maria that are named after people, the other being

Mare Humboldtianum Mare Humboldtianum (Latin ''humboldtiānum'', the "Sea of Alexander von Humboldt") is a lunar mare located just to the east of Mare Frigoris, in the center of Humboldtianum basin. It is located along the northeastern limb of the Moon, and cont ...

(named after German explorer

Alexander von Humboldt Friedrich Wilhelm Heinrich Alexander von Humboldt (14 September 1769 – 6 May 1859) was a German polymath, geographer, natural history, naturalist, List of explorers, explorer, and proponent of Romanticism, Romantic philosophy and Romanticism ...

). The Smythii basin where the mare is located is of the Pre-Nectarian

epoch In chronology and periodization, an epoch or reference epoch is an instant in time chosen as the origin of a particular calendar era. The "epoch" serves as a reference point from which time is measured. The moment of epoch is usually decided b ...

, while the surrounding features are of the

Nectarian The Nectarian Period of the lunar geologic timescale was from 3.920 billion years ago to 3.850 billion years ago. It is the period during which the Nectaris Basin and other major basins were formed by large impact events. Ejecta from Nectaris for ...

system. It is contained within a minimal diameter of , and has been excavated to a depth of . The mare material, which makes up the floor of the mare, is a low

alumina Aluminium oxide (or aluminium(III) oxide) is a chemical compound of aluminium and oxygen with the chemical formula . It is the most commonly occurring of several aluminium oxides, and specifically identified as aluminium oxide. It is commonly ...

basalt Basalt (; ) is an aphanite, aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the planetary surface, surface of a terrestrial ...

, and consists of Upper Imbrian basalt covered by

Eratosthenian The Eratosthenian period in the lunar geologic timescale runs from 3,200 million years ago to 1,100 million years ago. It is named after the crater Eratosthenes, which displays characteristics typical of craters of this age, including a surface ...

basalt. Features observed within the basin include

wrinkle ridge A wrinkle ridge is a type of feature commonly found on lunar maria, or basalt plains. These features are low, sinuous ridges formed on the mare surface that can extend for up to several hundred kilometers. Wrinkle ridges are tectonic features ...

s, submerged "ghost" craters,

domes A dome () is an architectural element similar to the hollow upper half of a sphere. There is significant overlap with the term cupola, which may also refer to a dome or a structure on top of a dome. The precise definition of a dome has been a m ...

crater chain A crater chain is a line of Impact crater, craters along the surface of an astronomical body. The descriptor term for crater chains is catena , plural catenae (Latin for "chain"), as specified by the International Astronomical Union's rules on ...

s, and

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 w ...

s. The overall shape of the mare is circular, likely the result of a large impact. Further bombardment followed, creating the irregular shape. Subsequent volcanism laid down the mare material. As a result of this sequence, only the northeastern portion and a smaller area in the western central contain significant regions of smooth mare material. The remaining surface is more hummocky with a higher albedo. The geological features suggest that lava flowed from the southeast and west toward the northeast, where it accumulated in the lowest parts of the basin. Mare Smythii contains a relatively high number of craters with fractured floors, including the noticeably unusual crater Haldane. This is probably a result of uplift from injection of magma below the mare. The crater Neper is located to the north of the mare. This crater makes up part of the southern rim of

Mare Marginis Mare Marginis (Latin for 'Sea of the Edge'); ) is a lunar mare that lies on the very edge of the lunar nearside. The selenographic coordinates of this feature are 13.3° N, 86.1° E, and the diameter is 358 km. This mare differs from most ...

. Just off to the northwest of the mare are the craters

Schubert Franz Peter Schubert (; ; 31 January 179719 November 1828) was an Austrian composer of the late Classical period (music), Classical and early Romantic music, Romantic eras. Despite his short life, Schubert left behind a List of compositions ...

and Schubert B. The dark mare-filled crater at the southern edge of Smythii is the crater

Kästner Kästner (transliterated Kaestner) is a German surname. Notable people with the surname include: * Abraham Gotthelf Kästner, (1719-1800), German mathematician ** Kästner (crater), a lunar crater * Detlef Kästner (born 1958), German boxer * Eri ...

Gallery

File:MareSmithiiTG.jpg, The topography (top) and corresponding gravity (bottom) signal of Mare Smythii reveals a mascon in its center File:Smythii basin topo.jpg, Topographic map File:Smythii basin GRAIL gravity.jpg, Gravity map based on

GRAIL The Holy Grail (, , , ) is a treasure that serves as an important motif in Arthurian literature. Various traditions describe the Holy Grail as a cup, dish, or stone with miraculous healing powers, sometimes providing eternal youth or sustenanc ...

File:Mare Smythii AS10-27-3915.jpg, View from

Apollo 10 Apollo 10 (May 18–26, 1969) was the fourth human spaceflight in the United States' Apollo program and the second to orbit the Moon. NASA, the mission's operator, described it as a "dress rehearsal" for the first Moon landing (Apollo 11, two ...

File:Mare Smythii AS16-M-3008.jpg, Oblique 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 ...

References

{{Lunar maria Smythii Smythii Smythii Smythii