The Celestial Odyssey: Our Moon's Mysteries

The Moon | A documentary on Solar System by Academic Block.

Moon is Earth’s only natural satellite, orbiting at an average distance of about 238,855 miles (384,400 kilometers). Its surface features include vast plains, craters, and mountains. With minimal atmosphere, temperature range from 253°F (123°C) in sunlight to -387°F (-233°C) in night, affecting tidal patterns on Earth.

Overview

The Moon, that luminous celestial companion we see gracing our night skies, has captivated human imagination for centuries. Its mysterious allure has led to lunar exploration, scientific studies, and an array of myths and legends. In this comprehensive guide, we'll dive into the captivating world of the Moon, uncovering lunar facts, its role in history, and the marvels of lunar science. By the end of this article by Academic Block, you'll gain a deep understanding of this enigmatic orb that has left an indelible mark on our collective consciousness.

Unveiling Lunar Mysteries

Moon possesses a mass of approximately 7.34 x 10²² kilograms and a diameter of about 3,474 kilometers. This makes it about 1/6th the size of Earth and considerably less massive. The average distance between the Moon and Earth is approximately 384,400 kilometers, allowing it to exert a significant influence on our planet's tides due to its gravitational pull. The Moon's journey around Earth takes roughly 27.3 days, which is why we observe different phases of the Moon during a month-long lunar cycle.

The Moon's Phases and Mystique

The Moon's ever-changing appearance, known as its phases, have fascinated humanity for generations. As the Moon orbits Earth, its illuminated side faces different angles, resulting in the well-known phases: New Moon, Waxing Crescent, First Quarter, Waxing Gibbous, Full Moon, Waning Gibbous, and Third Quarter. These phases have inspired poetry, art, and even cultural celebrations.

Moon's most distinctive features is its surface, adorned with countless craters. The Moon's surface is a rugged and fascinating terrain, dotted with vast plains, towering mountains, and deep craters. These craters are the result of a long history of impacts by meteoroids, asteroids, and comets. When these space objects collide with the Moon's surface at high speeds, they create depressions in the lunar terrain. Over time, these craters accumulate and form a unique topography. Some of the larger and more prominent craters, like Tycho and Copernicus, have become prominent features visible from Earth.

Moon craters are fascinating scientific windows into the Moon's history and the dynamics of our solar system. The energy released during these impacts can be immense, creating shockwaves that reshape the lunar crust and ejecting debris, which can form secondary craters. Additionally, the impact can expose underlying layers of rock and minerals, giving scientists a glimpse into the Moon's geological past.

Moon's gravity is weaker than Earth's, it’s gravitational acceleration is approximately 1/6th that of Earth. Diving deeper into lunar surface, we find that the Moon's core is smaller and less dense in Earth's comparision. Its core is believed to be composed of iron and nickel. Despite its smaller size, the Moon exerts a gravitational pull on Earth, causing tides in our oceans. This gravitational interaction has played a pivotal role in shaping Earth's environment over millions of years. Interestingly, the Moon's gravity is not uniform across its surface due to variations in its density and topography. The side of the Moon facing Earth, known as the near side, and the side hidden from view, known as the far side, experience gravitational interactions with our planet differently.

While the Moon lacks a substantial atmosphere compared to Earth, it does possess an exceedingly thin and tenuous exosphere. This fragile envelope is comprised of trace amounts of gases, including helium, neon, and hydrogen, among others. Unlike Earth's atmosphere, which offers protection and sustenance, the Moon's exosphere is an almost vacuum-like expanse that is constantly influenced by solar radiation and the solar wind. Despite its scant presence, the Moon's exosphere holds vital clues about the dynamics of interactions between the solar wind and the lunar surface, offering a unique opportunity for scientific exploration and insights into the broader understanding of celestial bodies' interactions with their surrounding environment.

The Science and Wonders of Our Moon

Composition and Origin of the Moon: Have you ever wondered, "What is the Moon made of?" The Moon primarily consists of rock and metal, with its surface dominated by a type of rock called basalt. Scientific research suggests that the Moon formed from debris ejected during a massive collision between a young Earth and a Mars-sized body. This impact ejected material into space, which eventually coalesced to form our Moon.
Lunar Mysteries and Research: While we've made significant strides in understanding the Moon, mysteries still abound. The Moon's origin, the presence of water ice in its polar regions, and the nature of its magnetic field continue to intrigue scientists. Ongoing research, often involving lunar missions and advanced telescopes, aims to unveil these secrets and provide a deeper understanding of our cosmic neighbor.

Space Race: Missions to the Moon

United States: Apollo Missions

Perhaps the most iconic lunar missions come from the United States' Apollo program. Beginning with Apollo 11 in 1969, the program achieved the historic feat of landing humans on the lunar surface for the first time. Neil Armstrong and Buzz Aldrin's footsteps on the Moon marked a giant leap for humanity. Subsequent Apollo missions (Apollo 11 to 17) continued to explore the Moon, conducting scientific experiments, collecting samples, and enhancing our knowledge of lunar geology. "That's one small step for man, one giant leap for mankind".

Soviet Union/Russia: Luna Missions

The Soviet Union, later succeeded by Russia, also made significant contributions to lunar exploration through its Luna missions. The Luna program, launched in the late 1950s, aimed to achieve milestones such as impacting the Moon, orbiting it, and even sending robotic landers. Luna 2, launched in 1959, became the first human-made object to reach the lunar surface. Subsequent missions, like Luna 16 and Luna 24, successfully retrieved lunar soil samples and returned them to Earth. Latest mission to the moon by Russia is Luna 25 in 2023, at 11:57 am UTC on 19th August 2023, Luna 25 crash landed on the moon’s surface due to the malfunctioning.

India: Chandrayaan Missions

India's space agency, ISRO, launched its Chandrayaan program to explore the Moon's surface and atmosphere. Chandrayaan-1, launched in 2008, discovered water molecules on the lunar surface. Chandrayaan-2, launched in 2019, aimed for a soft landing on the Moon's south pole, although the lander lost communication during descent. This mission was considered as a part success, as the Orbitor performed its task for many years. Chandrayaan-3, launched on 14^th July, 2023 is the latest moon mission by India. This mission by India proved to be brilliantly successful, as it became the first county to reach the south pole of the Moon. It safely landed it’s lander “Vikram” along with its rover “Pragyan” on 23^rd August, 2023. The major acheivements of this mission includes performing the hopping operation, discovering the presence of elements like, Oxygen (O), Titanium (Ti), Aluminium (Al), Iron (Fe), Calcium (Ca), Chromium (Cr), Manganese (Mn), Silicon (Si), and Sulfur (S). Findings from this Indian mission, will pave the way for future human presence on the moon.

European Space Agency: SMART-1

The European Space Agency (ESA) embarked on its own lunar mission with SMART-1, launched in 2004. SMART-1 employed innovative ion propulsion technology to reach the Moon and conduct scientific experiments. While its primary mission was to study the Moon's composition and topography, SMART-1 also provided crucial data on space propulsion techniques.

China: Chang'e Missions

China's lunar exploration program, named after the mythical Chinese Moon goddess Chang'e, has rapidly advanced in recent years. Only limited varifiable information is available on the Chineeses mission. Chang'e 3, was launched in 2013. Subsequent missions, like Chang'e 4 and Chang'e 5, will be focused on lunar geology and sample return.

International Collaborations: Lunar Reconnaissance Orbiter

The Lunar Reconnaissance Orbiter (LRO) is a NASA mission launched in 2009 to conduct detailed mapping of the Moon's surface. While led by NASA, the mission involved contributions from several international partners. LRO's high-resolution images and data have significantly contributed to our understanding of lunar geology and potential landing sites for future missions.

Human Settlements on the Moon: Artemis Program

The Artemis program, led by NASA (National Aeronautics and Space Administration), aims to land "the first woman and the next man" on the Moon and establish sustainable human exploration. This program builds upon the legacy of the Apollo missions and focuses on creating a sustainable presence on the lunar surface. The program aims to accomplish this through a series of missions, including Artemis I (an uncrewed flight test of the Space Launch System and the Orion spacecraft), Artemis II (the first crewed mission of Orion), and Artemis III (the mission that will return humans to the lunar surface).

Establishing lunar settlements could also serve as stepping stones for further interplanetary exploration, offering a platform for scientific research, resource utilization, and technological innovation. Challenges, such as the Moon's harsh environment, low gravity, and radiation exposure, necessitate innovative solutions in areas such as habitat design, food supply, life support systems, and resource management.

Artemis also involves the establishment of the Lunar Gateway, a space station that will orbit the Moon and serve as a staging point for lunar missions. Taking cues from the India's Chandrayaan program, this Gateway will provide a platform to serve as a base for lunar exploration, including missions to the Moon's south pole.

Unveiling Lunar Conspiracy Theories: Exploring the Myths and Realities

The Moon, a celestial object that has been a source of inspiration and curiosity for millennia, has also become a canvas for conspiracy theories that challenge established scientific understanding. These theories, often fueled by skepticism, misinformation, and a healthy dose of imagination, have captured the attention of many. In this segment, we dive into some of the most notable lunar conspiracy theories, examining their origins, claims, and the scientific realities that provide a counterbalance.

The Moon Landing Hoax

One of the most enduring conspiracy theories suggests that the Apollo Moon landings were an elaborate hoax staged by NASA and the U.S. government. Proponents of this theory argue that the footage of astronauts on the lunar surface was filmed on Earth and that the U.S. wanted to win the Space Race against the Soviet Union at any cost.

Scientific Reality: Multiple lines of evidence, including the physical Moon rock samples brought back by Apollo missions, reflectors left on the Moon's surface that are still used to measure lunar distance, and independent tracking of the missions by various nations, have confirmed the authenticity of the Moon landings. The claims of a hoax have been thoroughly debunked by experts in various fields.
Artificial Moon Structures: Some conspiracy theorists propose that there are unnatural structures or objects on the Moon, pointing to anomalies seen in photographs taken by lunar missions. These anomalies are sometimes interpreted as signs of extraterrestrial civilizations or advanced technology.
Scientific Reality: Anomalies observed in lunar photographs are often the result of lighting conditions, camera artifacts, or the limitations of low-resolution images. The scientific consensus is that there is no credible evidence to support the existence of artificial structures or objects on the Moon.
Hollow Moon Theory: According to this theory, the Moon is hollow and contains vast, secret chambers within its interior. Proponents suggest that this could explain anomalies in seismic data from lunar impacts and the Moon's lower-than-expected density.
Scientific Reality: The Moon's composition and seismic behavior are well understood through data collected from lunar missions. The Moon's density is consistent with what would be expected from its known composition of rock and metal. The hollow Moon theory lacks empirical evidence and contradicts the principles of planetary formation.
Moon's Dark Side and Secret Bases: Conspiracy theories also propose that the far side of the Moon, which is not visible from Earth, harbors hidden bases or extraterrestrial activity. Claims range from secret military installations to contact with alien civilizations.
Scientific Reality: The far side of the Moon has been thoroughly explored by robotic missions, and there is no credible evidence of secret bases or extraterrestrial contact. The lunar far side is just as geologically diverse and barren as the side facing Earth.

Benefits of Addressing Lunar Conspiracy Theories

While lunar conspiracy theories may capture public attention, it's important to approach them critically and skeptically. These theories often lack rigorous scientific evidence and are easily debunked by experts in relevant fields. Engaging with accurate information and scientific understanding is crucial to dispel misinformation and promote a better understanding of our universe.

Mythical Moons: Lunar Legends in Greek, Indian, and Roman Mythology

The Moon, with its mesmerizing presence in the night sky, has been a source of inspiration for countless cultures throughout history. Greek, Indian, and Roman civilizations each wove intricate myths and stories around the Moon, endowing it with significance, symbolism, and a touch of magic. Let's embark on a journey through the rich tapestry of lunar mythology in these ancient cultures.

Indian Mythology: Chandra and Som

In Indian mythology, the Moon is personified as Chandr, a god who presides over the lunar realm. Chandr's luminous presence is a symbol of purity, beauty, and tranquility. Legends often depict Chandr as a romantic figure, infusing moonlight with sentiments of love and longing. The Moon's association with the deity Som further enriches its significance. Som, sometimes referred to as a god or an elixir, is connected to the Moon's soothing and cooling influence. The Moon's phases, resembling waxing and waning cycles, mirror the ephemeral nature of life and its impermanent beauty.

Greek Mythology: Selene and Artemis

In Greek mythology, the Moon was personified as the goddess Selene, who was often depicted driving a chariot across the night sky, illuminating the world with her gentle light. Selene was associated with the tranquil and enchanting aspects of the Moon, casting a romantic and mystical ambiance over the land. Another significant figure was Artemis, the goddess of the hunt and the Moon. Artemis was revered as a protector of wild animals and a guardian of young women. Her connection to the Moon represented its cyclical nature, reflecting the phases of womanhood and the changing tides of life.

Roman Mythology: Luna and Diana

In Roman mythology, the Moon was personified as Luna, a goddess whose name reflects her luminous radiance. Luna was often depicted driving a chariot across the night sky, casting a gentle glow upon the world below. She was considered a protector of travelers and those who ventured out at night. Similarly, to the Greek Artemis, the Roman counterpart, Diana, also held sway over the Moon and the wilderness. Diana's association with the Moon highlighted its mysterious and untamed aspects, connecting the lunar realm to the realm of nature and the hunt.

Final Words

Across the ancient civilizations, the Moon's symbolism varies while retaining themes of purity, transformation, and the ebb and flow of life. Its influence on human emotions, the tides, and the natural world has led to the Moon's integration into narratives of love, mystery, and cycles of existence. The Moon's waxing and waning, its changing phases, and its ethereal light have fascinated and inspired generations, infusing the night sky with an otherworldly beauty that transcends time.

We hope, you will find this information on the moon useful and interesting. At Academic Block, we try to present you well researched articles. Please comment below, your suggestions and critism help us in improving our articles. Thanks for reading.

This Article will answer your questions like:

+ What is the Moon? >

The Moon is Earth's only natural satellite and the fifth-largest satellite in the Solar System. It is composed primarily of silicate rock and metal, featuring a solid crust, mantle, and core. The Moon has a significant impact on Earth, including its gravitational influence on ocean tides.

+ How far is the Moon from Earth? >

The average distance between the Moon and Earth is about 384,400 kilometers (238,855 miles). This distance varies due to the elliptical nature of the Moon's orbit, ranging from approximately 363,300 kilometers (225,623 miles) at perigee to 405,500 kilometers (251,966 miles) at apogee.

+ What is the size of the Moon compared to Earth? >

The Moon has a diameter of about 3,474 kilometers (2,159 miles), which is roughly 27% of Earth's diameter. Its volume is about 2% of Earth's, and its mass is about 1.2% of Earth's. Despite its smaller size, the Moon exerts significant gravitational effects on Earth.

+ How does the Moon affect Earth’s tides? >

The Moon's gravitational pull generates tidal forces, causing the Earth's oceans to bulge, leading to high and low tides. The tidal force causes two bulges on opposite sides of Earth, resulting in two high tides and two low tides each day. The Sun also influences tides, but to a lesser extent.

+ What is a blue moon? >

A "blue moon" is a term used to describe the second full moon in a calendar month, which occurs approximately once every two to three years. The term can also refer to the third of four full moons in a single season. Despite the name, a blue moon is not typically blue in color; the phrase simply represents an astronomical rarity.

+ Does the Moon have an atmosphere? >

The Moon has an extremely thin and tenuous atmosphere called an exosphere. It is composed of trace amounts of helium, neon, hydrogen, and other elements. This exosphere is so thin that it does not provide significant protection or weather effects like the thicker atmospheres of Earth or other planets.

+ What is sun and moon together called? >

The phenomenon of the Sun and Moon appearing together in the sky is commonly known as a "syzygy," though this term refers more broadly to the alignment of three celestial bodies. When the Sun and Moon are in close proximity, it may occur during phases like a solar eclipse or within specific parts of the lunar cycle. This alignment is significant in both astronomical and tidal phenomena.

+ What are the main 4 moon stages? >

The phases of the Moon are the different appearances of the Moon as seen from Earth, resulting from its orbit around Earth. The primary phases are New Moon, First Quarter, Full Moon, and Last Quarter, with intermediate waxing and waning crescent and gibbous phases between them.

+ Which country launched the first moon lander (lunar lander)? >

The Soviet Union launched the first successful moon lander, Luna 2, on September 12, 1959. Luna 2 became the first human-made object to reach the Moon's surface when it crash-landed on September 14, 1959. This achievement was part of the Soviet Union's Luna program, which sought to explore the Moon and achieve significant milestones in space exploration during the early space race.

+ Are there any missions planned to return to the Moon? >

Yes, several missions are planned to return to the Moon. NASA's Artemis program aims to land astronauts on the Moon by 2024, with plans for sustainable lunar exploration. Other space agencies, such as ESA, Roscosmos, CNSA, and private companies, are also planning lunar missions for exploration and research.

+ Is there water on the Moon? >

Yes, water has been detected on the Moon, primarily in the form of ice in permanently shadowed craters near the poles. Trace amounts of water molecules have also been found in the lunar soil. This discovery has significant implications for future lunar exploration and potential habitation.

+ Can you see the Moon during the day? >

Yes, the Moon can often be seen during the day, depending on its phase and position in the sky. It is most visible in the daytime during its first and last quarter phases. The Moon's brightness makes it visible against the blue sky during these periods.

+ What is the gravity like on the Moon compared to Earth? >

The Moon's gravity is about 1/6th of Earth's gravity. This means that objects on the Moon weigh significantly less than they do on Earth. For example, a person who weighs 60 kilograms (132 pounds) on Earth would weigh only 10 kilograms (22 pounds) on the Moon.

+ How does the Moon affect human behavior? >

While anecdotal evidence suggests the Moon affects human behavior, scientific studies have not conclusively proven a direct link. Cultural beliefs and folklore often attribute changes in behavior, such as increased sleep disturbances or psychological effects, to the full moon, but empirical evidence remains inconclusive.

+ What is the temperature like on the Moon? >

The Moon experiences extreme temperature variations due to its lack of atmosphere. Daytime temperatures can reach up to 127°C (260°F), while nighttime temperatures can drop to -173°C (-280°F). These extremes present significant challenges for lunar exploration and habitation.

+ What is the distance between Earth and Moon? >

The average distance between Earth and the Moon is about 384,400 kilometers (238,855 miles). This distance varies slightly due to the Moon's elliptical orbit, with its closest approach (perigee) being about 356,500 km and its farthest distance (apogee) being around 406,700 km.

Famous Quotes on the Moon

“The Moon is the first milestone on the road to the stars.” – Arthur C. Clarke

“The Moon is a friend for the lonesome to talk to.” – Carl Sandburg

“The Moon is a mysterious world of silence.” – Eugene Cernan

“The Moon was a phantom, floating in the soft black sky.” – George R. R. Martin

“The Moon’s an arrant thief, and her pale fire she snatches from the sun.” – William Shakespeare

“The Moon, like a flower in heaven’s high bower, with silent delight sits and smiles on the night.” – William Blake

“The Moon is the key to the solar system.” – Jay Barbree

“The Moon is not a piece of cheese to be nibbled at will.” – David Grinspoon

“The Moon is the mother of pathos and pity.” – Isabella Bird

“The Moon is the most intriguing celestial body.” – James Lovelock

“The Moon is a world of its own.” – Apollo 14 astronaut Alan Shepard

“The Moon is a mirror, reflecting the light of the sun.” – Neil Armstrong

“The Moon is a witness to human existence.” – Edwin Aldrin

“The Moon is a natural stepping stone for humanity to begin its journey to the stars.” – Gene Shoemaker

Old Published Research Articles on the moon

Published Research Articles:

George P. Kuiper. (1946). “The Lunar Surface.” Astrophysical Journal.
Reginald Aldworth Daly. (1946). “A New Theory of the Origin of the Moon.” Proceedings of the National Academy of Sciences of the United States of America.
Percival Lowell. (1897). “The Scenery of the Moon.” The Atlantic Monthly.
G. H. Darwin. (1879). “On the Early History of the Earth and Moon.” Proceedings of the Royal Society of London.
Sir George Biddell Airy. (1826). “On the Libration of the Moon.” Philosophical Transactions of the Royal Society of London.
J. F. Julius Schmidt. (1875). “Die Selenotopographische Fragmente.” Denkschriften der Kaiserlichen Akademie der Wissenschaften.
William Gilbert. (1600). “De Mundo Nostro Sublunari Philosophia Nova.” [English Translation: “New Philosophy About Our Sublunary World.”]

Reputable web references

NASA’s Moon Page: The official website of NASA provides a wealth of information on lunar exploration, missions, and scientific research. Website: NASA Moon
ISRO Official Website: The official website of ISRO provides information on its missions, projects, research, and developments. Website: ISRO Official Website
Lunar and Planetary Institute: This research institute offers educational resources and information on various aspects of the Moon and planetary science. Website: Lunar and Planetary Institute
Smithsonian National Air and Space Museum: The museum’s website provides articles, images, and resources on the history of lunar exploration and Apollo missions. Website: Smithsonian National Air and Space Museum
European Space Agency (ESA) – Moon Exploration: ESA’s dedicated page on Moon exploration offers news, updates, and scientific information on lunar missions. Website: ESA Moon Exploration
ISRO Space Science Portal: This section of ISRO’s website focuses on space science missions, research, and discoveries. Website: ISRO Space Science Portal
Planetary Science Institute: This institute’s website includes research articles and educational materials related to lunar science and exploration. Website: Planetary Science Institute
The Lunar and Planetary Institute’s Apollo Image Atlas: A collection of high-resolution images from the Apollo missions for detailed lunar surface exploration. Website: Apollo Image Atlas
The Planetary Society: Offers articles, news, and information on planetary exploration, including the Moon. Website: The Planetary Society
Space.com: Provides articles, news, and features on space exploration, including lunar topics. Website: Space.com
Sky & Telescope: Offers lunar observing guides, articles, and resources for amateur astronomers interested in the Moon. Website: Sky & Telescope
United States Geological Survey (USGS) Astrogeology Science Center: Provides lunar maps, images, and geological information. Website: USGS Astrogeology Science Center

Interesting facts on our Moon

Tidal Locking: The Moon is tidally locked to Earth, which means it always shows the same face towards us. This is why we only see one side of the Moon from Earth.

Rabbit in the Moon: In many cultures, people see patterns in the Moon’s surface. For example, the “Man in the Moon” or the “Rabbit in the Moon” are interpretations of the dark and light patterns on its surface.

Moon Phase: Moon phase refer to the changing appearance of the Moon as seen from Earth, caused by its orbit around Earth and the varying angles of sunlight hitting its surface.

Moonquakes: The Moon experiences seismic activity, just like Earth. Moonquakes are usually caused by the gravitational pull of Earth or by the cooling and contracting of the Moon’s interior.

Lunar Maria: The dark, flat plains on the Moon’s surface are called lunar maria (singular: mare). These areas were once thought to be seas by early astronomers due to their appearance, but they’re actually ancient lava plains.

Thin Atmosphere: The Moon has an extremely thin and tenuous atmosphere called an exosphere. It’s so thin that individual molecules can travel for kilometers before colliding with each other.

Moon Dust: The Moon’s surface is covered in a layer of fine, powdery dust known as regolith. This dust was created by the impact of meteoroids over billions of years.

Lunar Highlands: The light-colored, rugged regions on the Moon’s surface are called lunar highlands. These areas are older than the maria and are more heavily cratered.

Cold and Hot Extremes: Due to its lack of atmosphere, the Moon’s surface experiences extreme temperature variations. Temperatures can reach up to 127°C (260°F) during the day and plummet to -173°C (-280°F) at night.

Water Ice: Water ice has been discovered in the permanently shadowed regions of the Moon, mostly near the poles. This discovery has implications for potential future lunar exploration and even the possibility of supporting future missions.

Lunar Rilles: Lunar rilles are long, winding channels on the Moon’s surface. They were likely formed by lava flow or collapsed lava tubes in the Moon’s distant past.

Footprints on the Moon: The footprints left by astronauts on the Moon’s surface during the Apollo missions are expected to remain visible for millions of years due to the lack of atmosphere and weathering.

Microgravity: While the Moon has less gravity than Earth (about 1/6th), it’s still enough to influence tides on Earth and create microgravity conditions for scientific experiments.

Academic references in terms of books and published researched articles on moon

Books:

Wilhelms, D. E. (1987). “The Geologic History of the Moon.” U.S. Geological Survey Professional Paper 1348.
Taylor, S. R. (1992). “Solar System Evolution: A New Perspective.” Cambridge University Press.
Pieters, C. M., & Goswami, J. N. (Eds.). (1992). “Remote Geochemical Analysis: Elemental and Mineralogical Composition.” Cambridge University Press.
Spudis, P. D. (1996). “The Once and Future Moon.” Smithsonian Institution Press.
Sheehan, W. (1996). “The Immortal Fire Within: The Life and Work of Edward Emerson Barnard.” Cambridge University Press.
Neal, C. R., & Taylor, G. J. (1997). “The Lunar Crust: An Overview.” Geochimica et Cosmochimica Acta.