A lunar dome is a type of

shield volcano A shield volcano is a type of volcano named for its low profile, resembling a shield lying on the ground. It is formed by the eruption of highly fluid (low viscosity) lava, which travels farther and forms thinner flows than the more viscous lava ...

that is found on the surface of the

Earth Earth is the third planet from the Sun and the only astronomical object known to Planetary habitability, harbor life. This is enabled by Earth being an ocean world, the only one in the Solar System sustaining liquid surface water. Almost all ...

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 ...

. They are typically formed by highly viscous, possibly

silica Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula , commonly found in nature as quartz. In many parts of the world, silica is the major constituent of sand. Silica is one of the most complex and abundant f ...

-rich

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 Natural satellite, moon onto its surface. Lava may be erupted at a volcano or through a Fissure vent, fractu ...

, erupting from localized vents followed by relatively slow cooling. Lunar domes are wide, rounded, circular features with a gentle slope rising in elevation a few hundred meters to the midpoint. They are typically 8–12 km in diameter, but can be up to 20 km across. Some of the domes contain a small craterlet at the peak. Some of the domes have been shown to consist of the same materials as the lunar maria. Thus they could be created by some mechanism that differs from the mare-forming flows. It is thought that these domes are formed from a smaller

magma chamber A magma chamber is a large pool of liquid rock beneath the surface of the Earth. The molten rock, or magma, in such a chamber is less dense than the surrounding country rock, which produces buoyant forces on the magma that tend to drive it u ...

that is closer to the surface than is the case for a mare. This results in a lower pressure, and so the lava flows more slowly. The

magma Magma () is the molten or semi-molten natural material from which all igneous rocks are formed. Magma (sometimes colloquially but incorrectly referred to as ''lava'') is found beneath the surface of the Earth, and evidence of magmatism has also ...

wells up through a crack in the surface, but the flow eventually concentrates through one primary vent. This concentration can then result in a vent crater at the peak of the dome. The cluster of lunar domes at the Marius Hills was considered as a possible landing site of

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

. There are concentrations of lunar domes near the craters

Hortensius Quintus Hortensius Hortalus (114–50 BC) was a Roman Republic, Roman lawyer, an orator and a statesman. Politically he belonged to the Optimates. He was consul in 69 BC alongside Quintus Caecilius Metellus Creticus. His nickname was ''Dionysia ( ...

, and T. Mayer, across the top of Mons Rümker, and in Mare Fecunditatis. Solitary lunar domes are also found, including Kies Pi (π), Milichius Pi (π), Mons Gruithuisen Gamma (γ) and Delta (δ), and domes near the craters Gambart C,

Beer Beer is an alcoholic beverage produced by the brewing and fermentation of starches from cereal grain—most commonly malted barley, although wheat, maize (corn), rice, and oats are also used. The grain is mashed to convert starch in the ...

, and Capuanus. Omega Cauchy (ω) and Tau Cauchy (τ) form a pair of domes near the crater Cauchy. Likewise near Arago are the domes Arago Alpha (α) and Arago Beta (β). There are two domes south of Mons Esam. The IAU does not currently have rules that establish the naming of lunar domes, but the practice in the professional literature and in lunar sciences is to name the dome with the name of the nearest crater followed by a number that denotes the order of discovery.

Examples

File:Donna crater Omega Cauchy as08-13-2344hr.jpg, Omega Cauchy, with the small crater Donna at its summit, Mare Tranquillitatis File:Lunar dome AS11-42-6317.jpg, Oblique view of a dome north of Sinas, Mare Tranquillitatis File:Lunar dome near Messier crater 5038 med.jpg, Oblique view of lunar dome near Messier in Mare Fecunditatis. Note dark 'halo' deposits. The crater left of center is unrelated (formed after the dome). File:Lunar dome AS15-M-0424.jpg, Lunar dome south of

Mare Imbrium Mare Imbrium (Latin ''imbrium'', the "Sea of Showers" or "Sea of Rains") is a vast lunar mare, lava plain within the Imbrium Basin on the Moon and is one of the larger craters in the Solar System. The Imbrium Basin formed from the collision ...

File:Lunar domes Hortensius area 3123 h2.jpg, Oblique view of three of the six lunar domes north of

, from

Lunar Orbiter 3 The Lunar Orbiter 3 was a spacecraft launched by NASA in 1967 as part of the Lunar Orbiter program, Lunar Orbiter Program. It was designed primarily to photograph areas of the Moon, lunar surface for confirmation of safe landing sites for the S ...

File:Hortensius Domes (LRO).png, LRO image of the Hortensius domes File:Volcanoes in Lacus Veris (30x30km) 2.png, Domes in Lacus Veris, Orientale basin File:Mons Gruithuisen 4145 h1.jpg, Mons Gruithuisen Gamma (left) and Delta (right), from

Lunar Orbiter 4 Lunar Orbiter 4 was a robotic U.S. spacecraft, part of the Lunar Orbiter program, Lunar Orbiter Program, designed to orbit the Moon, after the three previous orbiters had completed the required needs for Project Apollo, Apollo mapping and site s ...

References

* Lionel Wilson and James W. Head,
Lunar Gruithuisen and Mairan domes: Rheology and mode of emplacement
", ''Journal of Geophysical Research'', vol. 108, 2003. * Lena, R., Wöhler, C., Phillips, J., Chiocchetta, M.T., "Lunar Domes:Properties and Formation Processes", "Springer Praxis Books", 2013,

.

External links

Marvin W. Huddleston, ALPO Lunar Dome Survey Coordinator's web page on Lunar DomesGLR Group Website
{{The Moon Volcanoes on the Moon, Shield volcanoes *Lunar dome Geologic domes

Examples

See also

References

External links