Mare Anguis (Latin ''anguis'', the "serpent sea") is a

lunar mare The lunar maria (; singular: mare ) are large, dark, basaltic plains on Earth's Moon, formed by ancient asteroid impacts on the far side on the Moon that triggered volcanic activity on the opposite (near) side. They were dubbed , Latin for 'seas' ...

located on the near side of 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 ...

, 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 runs from 3920 million years ago to 3850 million years ago. It is the period during which the Nectaris Basin and other major basins were formed by large impact events. Ejecta from Nectaris form ...

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

basalt Basalt (; ) is an 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 surface of a rocky planet or moon. More than 90% of a ...

. 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. The basin is of the Pre-Imbrian period, 4.55 to 3.85 billion years ago. Characteristics Mare C ...

. 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 with the chemical formula . It is a type of nesosilicate or orthosilicate. The primary component of the Earth's upper mantle, it is a common mineral in Earth's subsurface, but weathers qui ...

/low-Ca

pyroxene The pyroxenes (commonly abbreviated to ''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 calcium (Ca), sodium (Na), iron (Fe II) ...

mixture found in the

spectrum A spectrum (plural ''spectra'' or ''spectrums'') is a condition that is not limited to a specific set of values but can vary, without gaps, across a continuum. The word was first used scientifically in optics to describe the rainbow of color ...

References

{{moon-stub

Anguis SlowwormsThe "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 ha ...

See also

References