Mare Anguis (Latin ''anguis'', the "serpent 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 on the near side 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 ...

, about 150 kilometers in diameter. Located within the Crisium basin, Mare Anguis is a part of the Nectarian System, meaning that it was formed during 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 ...

time period. Like most mare, the surface of Mare Anguis is dark, indicating that it has been filled with volcanic

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 ...

. It forms part of a concentric ring to the northeast of the Crisium rim, and it lies at an elevation 800 m above

Mare Crisium Mare Crisium (Latin ''crisium'', the "Sea of Crises") is a lunar mare located in the Moon's Crisium basin, just northeast of Mare Tranquillitatis. Mare Crisium is a basin of Nectarian age. It was formed by the flooding of basaltic lava that fill ...

. Channels lead down from Mare Anguis to Mare Chrisium, with some possible indications of lava flow. The small, 7–km diameter crater Eimmart A lies at the east edge of Mare Anguis. It is a proposed source for the Antarctic meteorite ALHA81005. The impact appears to have excavated mare basalt, which probably accounts for the

olivine The mineral olivine () is a magnesium iron Silicate minerals, silicate with the chemical formula . It is a type of Nesosilicates, nesosilicate or orthosilicate. The primary component of the Earth's upper mantle (Earth), upper mantle, it is a com ...

/low-Ca

pyroxene The pyroxenes (commonly abbreviated Px) are a group of important rock-forming inosilicate minerals found in many igneous and metamorphic rocks. Pyroxenes have the general formula , where X represents ions of calcium (Ca), sodium (Na), iron ( ...

mixture found in the

spectrum A spectrum (: spectra or spectrums) is a set of related ideas, objects, or properties whose features overlap such that they blend to form a continuum. The word ''spectrum'' was first used scientifically in optics to describe the rainbow of co ...

References

{{moon-stub

Anguis Slow wormsThe "slow-" in slowworm is distinct from the English adjective ''slow'' ("not fast"); the word comes from Old English ''slāwyrm'', where ''slā-'' means "slowworm" and ''wyrm'' means "serpent, reptile". () (also called blindworms and h ...

See also

References