Mapped: The Geology of the Moon in Astronomical Detail
If you were to land on the Moon, where would you go?
Today’s post is the incredible Unified Geologic Map of the Moon from the USGS, which combines information from six regional lunar maps created during the Apollo era, as well as recent spacecraft observations.
Feet on the Ground, Head in the Sky
Since the beginning of humankind, the Moon has captured our collective imagination. It is one of the few celestial bodies visible to the naked eye from Earth. Over time different cultures wrapped the Moon in their own myths. To the Egyptians it was the god Thoth, to the Greeks, the goddess Artemis, and to the Hindus, Chandra.
Thoth was portrayed as a wise counselor who solved disputes and invented writing and the 365-day calendar. A headdress with a lunar disk sitting atop a crescent moon denoted Thoth as the arbiter of times and seasons.
Artemis was the twin sister of the sun god Apollo, and in Greek mythology she presided over childbirth, fertility, and the hunt. Just like her brother that illuminated the day, she was referred to as the torch bringer during the dark of night.
Chandra means the “Moon” in Sanskrit, Hindi, and other Indian languages. According to one Hindu legend, Ganesha—an elephant-headed deity—was returning home on a full moon night after a feast. On the journey, a snake crossed his pathway, frightening his horse. An overstuffed Ganesha fell to the ground on his stomach, vomiting out his dinner. On observing this, Chandra laughed, causing Ganesha to lose his temper. He broke off one of his tusks and hurled it toward the Moon, cursing him so that he would never be whole again. This legend describes the Moon’s waxing and waning including the big crater on the Moon, visible from Earth.
Such lunar myths have waned as technology has evolved, removing the mystery of the Moon but also opening up scientific debate.
Celestial Evolution: Two Theories
The pot marks on the Moon can be easily seen from the Earth’s surface with the naked eye, and it has led to numerous theories as to the history of the Moon. Recent scientific study brings forward two primary ideas.
One opinion of those who have studied the Moon is that it was once a liquid mass, and that its craters represent widespread and prolonged volcanic activity, when the gases and lava of the heated interior exploded to the surface.
However, there is another explanation for these lunar craters. According to G. K. Gilbert, of the USGS, the Moon was formed by the joining of a ring of meteorites which once encircled the Earth, and after the formation of the lunar sphere, the impact of meteors produced “craters” instead of arising from volcanic activity.
Either way, mapping the current contours of the lunar landscape will guide future human missions to the Moon by revealing regions that may be rich in useful resources or areas that need more detailed mapping to land a spacecraft safely .
Lay of the Land: Reading the Contours of the Moon
This map is a 1:5,000,000-scale geologic map built from six separate digital maps. The goal was to create a resource for science research and analysis to support future geologic mapping efforts.
Mapping purposes divide the Moon into the near side and far side. The far side of the Moon is the side that always faces away from the Earth, while the near side faces towards the Earth.
The most visible topographic feature is the giant far side South Pole-Aitken basin, which possesses the lowest elevations of the Moon. The highest elevations are found just to the northeast of this basin. Other large impact basins, such as the Maria Imbrium, Serenitatis, Crisium, Smythii, and Orientale, also have low elevations and elevated rims.
The colors on the map help to define regional features while also highlighting consistent patterns across the lunar surface. Each one of these regions hosts the potential for resources.
Only further study will resolve the evolution of the Moon, but it is clear that there are resources earthlings can exploit. Hydrogen, oxygen, silicon, iron, magnesium, calcium, aluminum, manganese, and titanium are some of the metals and minerals on the Moon.
Interestingly, oxygen is the most abundant element on the Moon. It’s a primary component found in rocks, and this oxygen can be converted to a breathable gas with current technology. A more practical question would be how to best power this process.
Lunar soil is the easiest to mine, it can provide protection from radiation and meteoroids as material for construction. Ice can provide water for radiation shielding, life support, oxygen, and rocket propellant feed stock. Compounds from permanently shadowed craters could provide methane, ammonia, carbon dioxide, and carbon monoxide.
This is just the beginning—as more missions are sent to the Moon, there is more to discover.
Space Faring Humans
NASA plans to land astronauts—one female, one male—to the Moon by 2024 as part of the Artemis 3 mission, and after that, about once each year. It’s the beginning of an unfulfilled promise to make humans a space-faring civilization.
The Moon is just the beginning…the skills learned to map Near-Earth Objects will be the foundation for further exploration and discovery of the universe.
How Is Aluminum Made?
Aluminum is one of the world’s most widely used metals, but producing it is a complex process. Here’s a look at where it comes from.
How is Aluminum Made?
Aluminum is one of our most widely-used metals, found in everything from beer cans to airplane parts.
However, the lightweight metal doesn’t occur naturally, and producing it is a complex process.
The Three Stages of Aluminum Production
Each year, the world produces around 390 million tonnes of bauxite rock, and 85% of it is used to make aluminum.
Bauxites are rocks composed of aluminum oxides along with other minerals and are the world’s primary source of aluminum. After mining, bauxite is refined into alumina, which is then converted into aluminum.
Therefore, aluminum typically goes from ore to metal in three stages.
Stage 1: Mining Bauxite
Bauxite is typically extracted from the ground in open-pit mines, with just three countries—Australia, China, and Guinea—accounting for 72% of global mine production.
|Country||2021 Mine Production of Bauxite (tonnes)||% of Total|
|Saudi Arabia 🇸🇦||4,300,000||1.1%|
|Rest of the World 🌍||15,500,000||4.0%|
Australia is by far the largest bauxite producer, and it’s also home to the Weipa Mine, the biggest bauxite mining operation globally.
Guinea, the third-largest producer, is endowed with more than seven billion tonnes of bauxite reserves, more than any other country. Additionally, Guinea is the top exporter of bauxite globally, with 76% of its bauxite exports going to China.
After bauxite is out of the ground, it is sent to refineries across the globe to make alumina, marking the second stage of the production process.
Stage 2: Alumina Production
In the 1890s, Austrian chemist Carl Josef Bayer invented a revolutionary process for extracting alumina from bauxite. Today—over 100 years later—some 90% of alumina refineries still use the Bayer process to refine bauxite.
Here are the four key steps in the Bayer process:
Bauxite is mixed with sodium hydroxide and heated under pressure. At this stage, the sodium hydroxide selectively dissolves aluminum oxide from the bauxite, leaving behind other minerals as impurities.
Impurities are separated and filtered from the solution, forming a residue known as red mud. After discarding the mud, aluminum oxide is converted into sodium aluminate.
The sodium aluminate solution is cooled and precipitated into a solid, crystallized form of aluminum hydroxide.
The aluminum hydroxide crystals are washed and heated in calciners to form pure aluminum oxide—a sandy white material known as alumina.
The impurities or red mud left behind in the alumina production process is a major environmental concern. In fact, for every tonne of alumina, refineries produce 1.2 tonnes of red mud, and there are over three billion tonnes of it stored in the world today.
China, the second-largest producer and largest importer of bauxite, supplies more than half of the world’s alumina.
|Country||2021 alumina production (tonnes)||% of total|
|Saudi Arabia 🇸🇦||1,800,000||1%|
|Rest of the World 🌍||15,100,000||11%|
Several major producers of bauxite, including Australia, Brazil, and India, are among the largest alumina producers, although none come close to China.
Alumina has applications in multiple industries, including plastics, cosmetics, and chemical production. But of course, the majority of it is shipped to smelters to make aluminum.
Stage 3: Aluminum Production
Alumina is converted into aluminum through electrolytic reduction. Besides alumina itself, another mineral called cryolite is key to the process, along with loads of electricity. Here’s a simplified overview of how aluminum smelting works:
- In aluminum smelter facilities, hundreds of electrolytic reduction cells are filled up with molten cryolite.
- Alumina (composed of two aluminum atoms and three oxygen atoms) is then dumped into these cells, and a strong electric current breaks the chemical bond between aluminum and oxygen atoms.
- The electrolysis results in pure liquid aluminum settling at the bottom of the cell, which is then purified and cast into its various shapes and sizes.
China dominates global aluminum production and is also the largest consumer. Its neighbor India is the second-largest producer, making only a tenth of China’s output.
|Country||2021 Aluminum Smelter Production (tonnes)||% of total|
|United Arab Emirates 🇦🇪||2,600,000||4%|
|Rest of the World 🌍||9,400,000||14%|
As is the case for alumina production, some of the countries that produce bauxite and alumina also produce aluminum, such as India, Australia, and Russia.
Roughly a quarter of annually produced aluminum is used by the construction industry. Another 23% goes into vehicle frames, wires, wheels, and other parts of the transportation industry. Aluminum foil, cans, and packaging also make up another major end-use with a 17% consumption share.
Aluminum’s widespread applications have made it one of the most valuable metal markets. In 2021, the global aluminum market was valued at around $245.7 billion, and as consumption grows, it’s projected to nearly double in size to $498.5 billion by 2030.
What Are Birthstones?
In this graphic, we look deep into 12 popular birthstones.
What Are Birthstones?
Many cultures throughout history have revered gemstones.
Gemstones are minerals, rocks, or organic matter that have been chosen for their beauty, durability, and rarity, and then cut or faceted, and polished to make jewelry or other human adornments. There are over 300 gemstones currently documented.
A birthstone is a gemstone that represents a person’s period of birth—usually corresponding to the month or zodiac sign.
In this graphic based on data from the American Gem Trade Association, we look deep into 12 popular birthstones.
What do Birthstones Mean?
Different ancient cultures revered gemstones and connected them to their calendar systems, so there are different lists of birthstones and months that can have more than one gemstone. In Hinduism, for example, there are nine gemstones associated with the Navagraha (celestial forces including the planets, the Sun, and the Moon), known in Sanskrit as Navaratna (nine gems).
Another origin of birthstones traces back to the book of Exodus in the Bible. In Exodus 28, Moses sets forth directions for making special garments for Aaron, the Hebrews’ High Priest and Moses’ elder brother. Specifically, the breastplate was to contain 12 precious gemstones, representing the 12 tribes of Israel.
Given the historical age and numerous translations of the Bible through the ages, there’s been a lot of debate around the identification of the 12 gemstones and no agreement on what the gems actually were.
About 1,500 years after Aaron’s time, in the first centuries of the Christian era, scholars started associating the breastplate gems with the signs of the zodiac. During the 18th century AD, gem traders began to sell gemstones based on a person’s birth month.
(USD per 1 carat size)
|Garnet||January||6.5-7.5||$175||Namibia, Sri Lanka, Russia|
|Aquamarine||March||7.5-8.0||$900||Brazil, Tanzania, Kenya|
|Diamond||April||10.0||$11,200||Botswana, Congo, Russia|
|Alexandrite||June||8.5||$23,500||Brazil, Russia, India|
|Ruby||July||9.0||$10,000||Myanmar, U.S., Thailand|
|Peridot||August||6.5-7.0||$650||U.S., Pakistan, Myanmar|
|Sapphire||September||9.0||$3,500||India, Australia, Madagascar|
|Opal||October||7.0-7.5||$350||Australia, Mexico, U.S.|
|Zircon||December||6.5-7.5||$400||Cambodia, Sri Lanka, Vietnam|
In some cultures, it is generally agreed that wearing a gemstone during the month when it is the birthstone heightens its healing powers.
The Birthstones Market
The majority of colored gemstones are extracted by artisanal mining communities around the world, in a very decentralized market.
Gemstone prices can vary from $68 per carat for citrine (November) up to $23,500 per carat for Alexandrite (June). The United States is the leading global market, buying roughly $24 billion in gemstones per year.
Besides different colors and prices, birthstones are also measured according to their hardness. The hardness is evaluated using a scale of 1-10 created by Friedrich Mohs that considers the ability to resist scratching. Diamonds (April) rank 10, being 58 times harder than any other mineral on Earth.
To this day, jewelers continue to add options to birthstone lists. Citrine and spinel (August), for example, are modern additions. Likewise, Tanzanite (December)—the second fastest-selling colored gemstone after Sapphire (September)—was only discovered in 1967 by herders in Tanzania.
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