Lacus Autumni (

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 ...

''autumnī'', "Lake of Autumn") is a region of

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' ...

that lies near the western limb 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 of ...

. Along this side of the lunar surface is a huge impact basin centered on the

Mare Orientale Mare Orientale (Latin ''orientāle'', the "eastern sea") is a lunar mare. It is located on the western border of the near side and far side of the Moon, and is difficult to see from an Earthbound perspective. Images from spacecraft have reveale ...

. Two concentric mountain rings surround the Orientale mare, the inner ring being named

Montes Rook Montes Rook is a ring-shaped mountain range that lies along the western limb of the Moon, crossing over to the far side. It completely encircles the Mare Orientale, and forms part of a massive impact basin feature. This range in turn is encircled ...

and an outer ring called the

Montes Cordillera Montes Cordillera is a mountain range on the Moon. This feature forms the outer wall of peaks that surround the Mare Orientale impact basin, the inner ring being formed by the Montes Rook. The center of the range is located at selenographic coord ...

. Lacus Autumni lies in the northeastern quadrant of the gap between these two mountain rings. This section of the lunar surface is difficult to observe directly from the Earth. The selenographic coordinates of the center of the mare are 9.9° S, 83.9° W. It is approximately long and trends from the southeast to the northwest, reaching a maximum width of . The irregular appearance results from the lunar

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 ...

emerging from the surface to fill in low areas between hummocky hills. The name of the feature was approved by the

IAU The International Astronomical Union (IAU; french: link=yes, Union astronomique internationale, UAI) is a nongovernmental organisation with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach ...

in 1970.Lacus Autumni
Gazetteer of Planetary Nomenclature, International Astronomical Union (IAU) Working Group for Planetary System Nomenclature (WGPSN)

References

External links

Lunar Orbiter Photo Number IV-181-H2
{{Lunar maria Autumni, Lacus