9.1 General Properties of the Moon
3 min read•june 12, 2024
The Moon's composition and structure have been unveiled through and remote sensing. These explorations reveal a world of crust, seismic activity, and a small molten core. The Moon's unique properties, from its mass to its , shape its distinct character.
Lunar surface features tell a tale of cosmic impacts, ancient volcanism, and tectonic shifts. Unlike Earth's dynamic landscape, the Moon's terrain remains largely unchanged, preserving a record of its violent past. This stark contrast highlights the Moon's role as a cosmic time capsule.
The Moon's Composition, Structure, and Physical Properties
Lunar exploration's scientific impact
Top images from around the web for Lunar exploration's scientific impact
Exploration of the Moon - Wikipedia View original
Is this image relevant?
File:Apollo 11 lunar module.jpg - Wikipedia View original
Is this image relevant?
File:Internal Structure of the Moon.JPG View original
Is this image relevant?
Exploration of the Moon - Wikipedia View original
Is this image relevant?
File:Apollo 11 lunar module.jpg - Wikipedia View original
Is this image relevant?
1 of 3
Top images from around the web for Lunar exploration's scientific impact
Exploration of the Moon - Wikipedia View original
Is this image relevant?
File:Apollo 11 lunar module.jpg - Wikipedia View original
Is this image relevant?
File:Internal Structure of the Moon.JPG View original
Is this image relevant?
Exploration of the Moon - Wikipedia View original
Is this image relevant?
File:Apollo 11 lunar module.jpg - Wikipedia View original
Is this image relevant?
1 of 3
- Apollo missions and lunar sample returns provide direct evidence of Moon's composition and structure
- Analysis of returned lunar rocks and soil reveal Moon's crust primarily composed of anorthosite, an igneous rock rich in calcium and aluminum
- conducted by astronauts during Apollo missions provide insights into Moon's interior structure
- Moon has a crust, mantle, and a small, partially molten core
- Lunar crust thicker on the far side compared to the near side
- Remote sensing data from further enhance understanding of Moon's surface composition and mineralogy
- Spectral data identify presence of various minerals, such as , , and , in addition to anorthosite
Key properties of the Moon
- Moon has a mass of 7.34 x 10^22 kg, approximately 1.2% of Earth's mass
- Moon's gravity about 1/6th that of Earth's, with a surface gravitational acceleration of 1.62 m/s^2
- Lower gravity on Moon due to its smaller mass compared to Earth
- Reduced gravity affects behavior of objects and materials on lunar surface (motion of astronauts, shape of impact craters)
- Moon lacks a significant atmosphere
- Lunar atmosphere considered an , with extremely low density and pressure
- Lack of substantial atmosphere attributed to Moon's low gravity and inability to retain atmospheric gases
- Absence of atmosphere results in lack of weather phenomena (wind, precipitation) on lunar surface
- Moon exhibits , always showing the same face to Earth
Moon vs Earth surface features
- Moon's surface characterized by impact craters, volcanic features, and tectonic structures, while Earth's surface dominated by plate tectonics, erosion, and weathering
- Impact craters more prevalent and better preserved on Moon due to lack of atmospheric protection and weathering processes
- Moon's craters range in size from micrometers to hundreds of kilometers in diameter
- Volcanic features on Moon include , , and domes
- Mare basalts are vast, dark plains of solidified lava that fill many of Moon's impact basins ()
- Sinuous rilles are channel-like features thought to be formed by ancient lava flows
- Domes are small, rounded hills that may represent volcanic constructs
- Tectonic structures on Moon primarily a result of its thermal history and include and
- Wrinkle ridges are linear, raised features that form due to compressional stresses in lunar crust
- Graben are linear depressions bounded by parallel normal faults, indicating extensional stress
- Impact craters more prevalent and better preserved on Moon due to lack of atmospheric protection and weathering processes
- Moon lacks active plate tectonics, hydrological cycle, and atmospheric processes that shape Earth's surface
- Absence of these processes results in relatively static and ancient lunar surface compared to Earth's dynamic and continually evolving surface
- , caused by micrometeorite impacts and solar wind bombardment, is primary weathering process on Moon
- Space weathering alters optical properties and chemical composition of lunar over time, darkening and reddening its appearance
Lunar Surface Features
- : Light-colored, heavily cratered regions of the Moon's surface, primarily composed of anorthosite
- : Concentrations of mass beneath the lunar surface, often associated with impact basins and affecting the Moon's gravitational field
Key Terms to Review (26)
Anorthosite: Anorthosite is a type of intrusive igneous rock that is composed almost entirely of the mineral plagioclase feldspar. It is a key component of the lunar crust and is closely associated with the general properties of the Moon.
Apollo Missions: The Apollo missions were a series of spaceflight programs conducted by NASA in the 1960s and 1970s, with the ultimate goal of landing astronauts on the Moon and safely returning them to Earth. These missions represented a significant technological and scientific achievement, expanding our understanding of the Moon's general properties and the broader solar system.
Apollo program: The Apollo program was a series of space missions conducted by NASA between 1961 and 1972 aimed at landing humans on the Moon and bringing them safely back to Earth. It culminated in six successful manned lunar landings, significantly advancing our understanding of the Moon's properties.
Exosphere: The exosphere is the outermost layer of a planet's atmosphere, where atoms and molecules escape into space. It is the transition zone between the atmosphere and the vacuum of space, and it plays a crucial role in the atmospheric and planetary dynamics of Earth, the Moon, and Mercury.
Graben: A graben is a depressed block of land bordered by parallel faults or fault systems. It is a type of rift valley formed by the downward displacement of a block of the earth's crust, resulting in a long, narrow trough-like depression with steep walls on either side.
Highlands: Highlands are elevated regions on the lunar surface, characterized by rugged terrain and a high density of impact craters. They are typically older than the lunar maria and have a bright appearance due to their composition of anorthosite rocks.
Highlands: Highlands refer to the elevated, mountainous regions on the surface of the Moon. These areas are characterized by their rugged, cratered terrain and are distinct from the relatively flat and smooth lowland regions known as maria.
Ilmenite: Ilmenite is a titanium-iron oxide mineral that is a primary ore of titanium. It is an important component in the study of the Moon's surface and composition, particularly in the context of the Moon's general properties and lunar surface features.
Lunar exploration: Lunar exploration involves the study and investigation of the Moon through manned and unmanned missions. It aims to understand the Moon's composition, history, and potential resources.
Lunar Maria: Lunar maria are the large, dark, flat areas on the surface of the Moon. They are solidified basaltic lava flows that filled in large impact basins created by asteroid and comet impacts in the Moon's distant past.
Lunar missions: Lunar missions are space expeditions aimed at exploring the Moon, including its surface, composition, and potential for future human habitation. These missions can be manned or unmanned and have provided significant insights into the Moon's general properties.
Lunar Orbiters: Lunar orbiters are artificial satellites that have been sent to orbit the Moon, providing valuable data and imagery to support our understanding of the Moon's general properties. These spacecraft have played a crucial role in advancing our knowledge of the lunar surface, geology, and environment.
Mare Basalts: Mare basalts are a type of volcanic rock that covers large portions of the lunar surface, particularly in the low-lying regions known as lunar maria. These dark-colored basaltic rocks were formed by the eruption and solidification of molten lava on the Moon, and they provide important insights into the geological history and evolution of Earth's natural satellite.
Mascons: Mascons, short for mass concentrations, are large, dense regions beneath the surface of the Moon that create significant gravitational anomalies. These features are important in understanding the general properties of the lunar surface and its formation.
Moon’s interior: The Moon's interior consists of three primary layers: the crust, mantle, and core. These layers differ in composition and physical properties, contributing to the Moon's geological characteristics.
Moon’s properties: The Moon's properties include its physical and orbital characteristics. These properties encompass aspects such as size, composition, surface features, and its interaction with Earth and the Sun.
Olivine: Olivine is a common silicate mineral found in the Earth's crust and mantle, as well as in the Moon and other planetary bodies. It is a magnesium-iron silicate with the chemical formula (Mg,Fe)2SiO4, and is an important component in the composition of the lunar surface and the planet Mercury.
Pyroxene: Pyroxene is a group of silicate minerals that are common in the Earth's crust and are also found in the lunar surface and on the planet Mercury. They are important rock-forming minerals that play a significant role in the composition and characteristics of these celestial bodies.
Regolith: Regolith is the layer of loose, unconsolidated rock and dust that covers the surface of a planetary body, such as the Moon, Mercury, or Mars. It is the result of the continuous breakdown and weathering of the underlying bedrock through various geological processes.
Schmitt: Schmitt, also known as Harrison Schmitt, was the last person to set foot on the Moon during the Apollo 17 mission. He is significant for being a geologist and bringing back valuable lunar samples.
Seismic Experiments: Seismic experiments are scientific investigations that use the propagation of seismic waves to study the internal structure and composition of planetary bodies, such as the Moon. These experiments involve the generation and detection of seismic waves to gather data about the subsurface features and properties of the target object.
Sinuous Rilles: Sinuous rilles are long, winding channels found on the surface of the Moon. These features are believed to have formed through the erosion and collapse of underground lava tubes, creating meandering depressions on the lunar surface.
Space Weathering: Space weathering refers to the physical and chemical changes that occur on the surfaces of celestial bodies, such as the Moon, due to their exposure to the harsh environment of space. This process alters the appearance and composition of these surfaces over time, providing valuable insights into the history and evolution of planetary bodies.
Synchronous rotation: Synchronous rotation is when an astronomical body's rotational period matches its orbital period around a partner, causing the same side to always face that partner. The Moon exhibits synchronous rotation with Earth, which is why we only see one hemisphere of the Moon from our planet.
Synchronous Rotation: Synchronous rotation, also known as tidal locking, is a phenomenon where the rotational period of a celestial body, such as a moon or planet, is equal to its orbital period around another body. This results in the same side of the rotating body always facing the body it orbits.
Wrinkle Ridges: Wrinkle ridges are long, narrow, and sinuous features found on the surface of the Moon and Mercury. They are formed by the compression and wrinkling of the planetary crust as it cools and contracts over time, creating a series of parallel or intersecting ridges that resemble wrinkles on the surface.