Neil A. Armstrong, Public domain

The Moon Quiz

How much do you know about the Moon?

Test your lunar knowledge with our Moon Quiz! How much do you really know about Earth's closest celestial neighbor? From its ancient craters to its role in culture and science, the Moon has fascinated humanity for millennia.

This quiz will challenge your understanding of the Moon's formation, its phases, its influence on Earth, and the history of lunar exploration. Are you ready to prove your lunar expertise and perhaps learn something new along the way? Let's find out!

Start the the Moon quiz

Questions and answers about the Moon

• How far is the Moon from Earth?

  The average distance from the Moon to Earth is about 384,400 kilometers (238,855 miles). This distance can vary slightly due to the Moon's elliptical orbit around Earth. At its closest point (perigee), the Moon is about 363,300 kilometers (225,623 miles) from Earth, and at its farthest point (apogee), it's about 405,500 kilometers (251,966 miles) away. This variation in distance affects the Moon's apparent size in the sky and contributes to the phenomena of supermoons and micromoons.

  • About 384,400 kilometers (238,855 miles) on average, varying due to its elliptical orbit.
  • Exactly 500,000 kilometers (310,686 miles) at all times, as the Moon's orbit is perfectly circular.
  • Approximately 1 million kilometers (621,371 miles), making it one of the farthest natural satellites in the solar system.
  • Constantly changing, with no average distance, due to the Moon's irregular orbit.

• What causes the Moon's phases?

  The Moon's phases are caused by the changing angles of illumination by the Sun and the Moon's position in its orbit around Earth. As the Moon orbits Earth, different portions of its surface are lit up by the Sun, leading to the various phases. These range from new moon (when the Moon is between the Sun and Earth, with the side facing Earth not illuminated) to full moon (when the Moon is on the opposite side of Earth from the Sun, fully illuminated). The phases progress through a cycle of waxing (increasing illumination) and waning (decreasing illumination), completing a full cycle approximately every 29.5 days.

  • Changing angles of illumination by the Sun and the Moon's position in its orbit around Earth.
  • Earth's shadow passing over the Moon as it orbits Earth.
  • The rotation of the Moon on its axis, revealing different portions of its surface.
  • Fluctuations in the Moon's brightness caused by changes in its surface temperature.

• Has the Moon always had the same side facing Earth?

  Yes, the Moon has always had the same side facing Earth in the recent geological past, a phenomenon known as synchronous rotation or tidal locking. This occurs because the Moon rotates on its axis in about the same time it takes to orbit Earth, approximately 27.3 days. As a result, one hemisphere of the Moon, the near side, is constantly facing Earth, while the other side, the far side, remains hidden from direct view. This synchronous rotation is the result of gravitational interactions between Earth and the Moon over billions of years, which have gradually slowed the Moon's rotation to match its orbital period.

  • Yes, due to synchronous rotation or tidal locking, with the same side always facing Earth.
  • No, the Moon used to rotate freely, showing all sides to Earth, until a massive impact stopped its rotation.
  • Only for the past few centuries, as a result of recent shifts in the Moon's orbit.
  • The side facing Earth changes over centuries due to irregularities in the Moon's rotational speed.

• What are the dark areas on the Moon called?

  The dark areas on the Moon are known as "maria," which is Latin for "seas." Early astronomers mistakenly thought these dark plains were actual seas. The maria are vast, basaltic plains formed by ancient volcanic eruptions. They are generally found on the near side of the Moon, which faces Earth, and are fewer and smaller on the far side. The maria cover about 16% of the lunar surface, predominantly in the lunar lowlands, and are younger than the brighter highland regions. Their dark color is due to the iron-rich minerals in the basaltic rock, which absorb more sunlight than the surrounding highlands.

  • "Maria," dark basaltic plains formed by ancient volcanic eruptions.
  • "Lacunae," ancient lunar lakes thought to be filled with dark matter.
  • "Selenaecum," regions of dense shadow cast by high lunar mountains.
  • "Asteriae," dark spots believed to be the remnants of old, collapsed stars.

• How did the Moon form?

  The prevailing theory on the Moon's formation is the giant impact hypothesis. According to this theory, the Moon formed about 4.5 billion years ago when a Mars-sized body, often referred to as Theia, collided with the early Earth. This catastrophic impact ejected a large amount of debris into Earth's orbit, which coalesced to form the Moon. This theory explains several aspects of the Moon's composition and the Earth-Moon system, such as their similar isotopic compositions and the Moon's relatively low density compared to Earth. Recent studies and lunar samples returned by the Apollo missions have provided strong support for this hypothesis.

  • Formed about 4.5 billion years ago from debris ejected into Earth's orbit following a giant impact with a Mars-sized body.
  • Originally a separate planet that was captured by Earth's gravity during the early solar system formation.
  • Formed simultaneously with Earth from the same accreting material in the protoplanetary disk.
  • Created by a massive explosion on Earth's surface, ejecting material that later formed the Moon.

• What is the name of the first manned mission to land on the Moon?

  The first manned mission to successfully land on the Moon was Apollo 11. This historic mission was launched by NASA, the United States space agency, on July 16, 1969. The lunar module, named "Eagle," landed on the Moon's surface on July 20, 1969. Astronauts Neil Armstrong and Edwin "Buzz" Aldrin became the first and second humans, respectively, to walk on the Moon, while Michael Collins remained in lunar orbit aboard the command module. Armstrong's first step onto the lunar surface was broadcast on live TV to a worldwide audience. He famously described the event as "one small step for [a] man, one giant leap for mankind."

  • Apollo 13
  • Luna 9
  • Apollo 11
  • Mercury-Redstone 3

• How long does it take the Moon to orbit the Earth?

  The Moon takes approximately 27.3 days to complete one orbit around the Earth. This period, known as the sidereal month, is measured by tracking the Moon's position relative to distant stars. However, due to the Earth's movement around the Sun, the time from one full moon to the next – known as the synodic month – is about 29.5 days. This difference arises because as the Earth orbits the Sun, the Moon has to travel a little further to reach the same phase, such as from full moon to full moon.

  • About 24 hours
  • Approximately 365 days
  • Approximately 27 days
  • About 7 days

• What are the highlands on the Moon?

  The highlands on the Moon, often referred to as lunar highlands, are lighter-colored areas heavily cratered and typically situated at higher elevations compared to the darker lunar maria (basaltic plains). These highlands are composed primarily of anorthosite, a type of rock rich in calcium and aluminum silicates. They are thought to represent the original crust of the Moon, formed as lighter material floated to the surface of the molten early Moon. The lunar highlands are much older than the maria, with many of the craters dating back to the heavy bombardment phase of the solar system's early history.

  • Dark, flat basaltic plains formed by ancient volcanic eruptions
  • Lighter-colored, heavily cratered regions at higher elevations
  • Areas where astronauts have landed and conducted moonwalks
  • Regions rich in ice and other frozen volatiles at the Moon's poles

• What is the difference between a lunar eclipse and a solar eclipse?

  A lunar eclipse and a solar eclipse are two different astronomical events, each involving the alignment of the Earth, Moon, and Sun. A lunar eclipse occurs when the Earth comes between the Sun and the Moon, and the Earth's shadow falls on the Moon. This can only happen during a full moon. On the other hand, a solar eclipse occurs when the Moon comes between the Sun and the Earth, casting a shadow on Earth. This occurs during a new moon. In a lunar eclipse, the Moon can appear red due to Earth's atmosphere bending sunlight into the shadow, while in a solar eclipse, the Moon blocks the Sun's light, partially or totally obscuring the Sun from view.

  • Lunar eclipse is when the Moon passes between the Earth and the Sun; solar eclipse is when the Earth passes between the Sun and the Moon
  • Lunar eclipse is when the Moon appears larger than usual; solar eclipse is when it appears smaller
  • Lunar eclipse can occur during any moon phase; solar eclipse only during a full moon
  • Lunar eclipse is when the Earth's shadow falls on the Moon; solar eclipse is when the Moon's shadow falls on Earth

• What causes the phenomenon known as a "blue moon"?

  A "blue moon" is a term often used to describe a rare event, specifically in the context of the full moon. Traditionally, it refers to the occurrence of a second full moon within a single calendar month. Since the lunar cycle is about 29.5 days, most months have only one full moon, but occasionally, a second one sneaks in, known as a "blue moon." Another, less common definition is the third full moon in a season that has four full moons (as opposed to the usual three). Contrary to its name, a blue moon does not appear blue in color; the term is purely a reference to its rarity.

  • When the Moon's surface appears blue due to atmospheric conditions on Earth
  • The occurrence of a second full moon in a single calendar month
  • A full moon occurring on the winter solstice
  • A rare alignment of multiple moons in the solar system

• How does the Moon's gravitational pull affect Earth?

  The Moon's gravitational pull has several significant effects on Earth. The most notable is the creation of tides. The Moon's gravity pulls on Earth's oceans, causing the water to bulge out on the side closest to the Moon and, due to inertia, on the opposite side as well. This results in high and low tides. The Moon's gravitational influence also contributes to the stabilization of Earth's axial tilt, which helps maintain a relatively stable climate. Additionally, the gravitational interaction between Earth and the Moon is causing the Moon to slowly move away from Earth at a rate of about 3.8 centimeters per year, and it also gradually slows Earth's rotation, lengthening our days over long time periods.

  • Creates tides by influencing Earth's oceans, contributes to Earth's axial tilt stability, and gradually distances the Moon from Earth.
  • Influences Earth's rotation, potentially altering day length over millennia, contrary to the gradual lengthening observed.
  • Is mistakenly believed by some to generate Earth's magnetic field, which is crucial for repelling solar winds and radiation.
  • Indirectly impacts seasonal changes and weather patterns by affecting Earth's tilt and orbit, though primarily through solar interactions.

• What is the temperature range on the Moon?

  The temperature range on the Moon is extremely wide due to the lack of an atmosphere to retain heat. During the lunar day at the equator, temperatures on the Moon's surface can reach up to about 120 degrees Celsius (250 degrees Fahrenheit). At night, temperatures can plummet to as low as -130 degrees Celsius (-208 degrees Fahrenheit). In certain spots near the Moon's poles, temperatures can drop even further, reaching -253 degrees Celsius (-424 degrees Fahrenheit). This drastic temperature variation presents a significant challenge in designing spacecraft and equipment for lunar missions, as they must be able to withstand both extremes.

  • Up to about 120 degrees Celsius (250 degrees Fahrenheit) during the day and down to -130 degrees Celsius (-208 degrees Fahrenheit) at night.
  • Constantly cold, around -50 degrees Celsius (-58 degrees Fahrenheit), regardless of day or night.
  • Uniformly warm, approximately 35 degrees Celsius (95 degrees Fahrenheit), due to internal heating.
  • Extreme heat of up to 500 degrees Celsius (932 degrees Fahrenheit) during the day and moderate temperatures at night.

• What are lunar maria, and how were they formed?

  Lunar maria are large, dark basaltic plains on the Moon, formed from ancient volcanic eruptions. They are less cratered than the highland areas and appear dark due to the iron-rich minerals in the basalt. The maria were formed between about 3 and 3.5 billion years ago when large impact basins were filled with molten rock from the Moon's interior. These basins were created during a period of heavy meteorite and asteroid bombardment. The lava flows that created the maria were extensive, covering large areas, and as they cooled and solidified, they formed the flat plains we see today.

  • Dark basaltic plains formed from ancient volcanic eruptions, filling large impact basins with molten rock.
  • Regions filled with water in the Moon's early history, now dried up and leaving behind dark sediment.
  • Areas covered in dense forests and vegetation, giving them a darker appearance from space.
  • Depressions caused by the gravitational pull of Earth, collecting darker cosmic dust and debris.

• How many Apollo missions landed on the Moon?

  Out of the Apollo space program, six missions successfully landed on the Moon. These were Apollo 11, 12, 14, 15, 16, and 17. The first successful manned moon landing was Apollo 11 in July 1969, with astronauts Neil Armstrong and Buzz Aldrin becoming the first and second humans, respectively, to walk on the Moon. The last manned Moon landing was Apollo 17 in December 1972. Although Apollo 13 was intended to land on the Moon, it famously had to abort its lunar landing due to an in-flight spacecraft malfunction and returned safely to Earth.

  • Six missions: Apollo 11, 12, 14, 15, 16, and 17, with Apollo 11 being the first in 1969.
  • Three missions: Apollo 11, 12, and 13, with the program ending after the Apollo 13 accident.
  • Eight missions, starting with Apollo 11 and ending with Apollo 18, which was the last to land on the Moon.
  • Just one, Apollo 11, as all subsequent missions were unmanned or orbited the Moon without landing.

• Why do we always see the same side of the Moon from Earth?

  The reason we always see the same side of the Moon from Earth is due to the Moon's synchronous rotation, or tidal locking. This means the Moon rotates on its axis in the exact amount of time it takes to orbit Earth. This alignment allows only one hemisphere of the Moon to be visible from Earth, a phenomenon that played a crucial role in lunar observation and exploration. Before the era of space exploration, this resulted in the far side of the Moon being unknown. The synchronous rotation reflects a stable orbital and rotational history, offering insights into the Moon's formation, its evolutionary path, and the nature of Earth-Moon gravitational interactions over eons.

  • Synchronous rotation keeps one hemisphere facing Earth due to the Moon's orbit and rotation period matching.
  • The Moon's rotation speed increases when closer to Earth, locking its position.
  • Earth's stronger gravitational pull on one side of the Moon prevents it from rotating.
  • The Moon was originally a part of Earth, and it maintains its initial orientation.

• What are the most prominent craters on the Moon?

  The Moon is home to numerous craters, but some of the most prominent include Tycho, Copernicus, and Clavius. Tycho is one of the most easily identifiable craters, known for its bright ray system that extends across much of the lunar surface. Copernicus is another significant crater, notable for its size and the complex system of rays that emanate from it. Clavius is one of the largest crater formations on the Moon and is easily visible through a small telescope. These craters were formed by impacts from asteroids or comets and are characterized by their distinctive features, such as central peaks, terraced walls, and surrounding ejecta blankets.

  • Mare Imbrium, Mare Serenitatis, and Mare Nectaris
  • Tycho, Copernicus, and Clavius
  • Tranquillitatis, Fecunditatis, and Nubium
  • Aristotle, Ptolemy, and Eratosthenes

• How does the lack of atmosphere affect the Moon's surface?

  The lack of a significant atmosphere on the Moon has several profound effects on its surface. First, it means the Moon is unprotected from meteoroids, leading to a surface heavily scarred by craters from impacts. Without an atmosphere, there is no weathering or erosion as seen on Earth, so impact craters and other surface features can remain unchanged for billions of years. Additionally, the absence of an atmosphere results in extreme temperature fluctuations, with the Moon's surface being extremely hot during the day and bitterly cold at night. There is also no protection from solar radiation and cosmic rays, making the surface environment much harsher than on Earth.

  • Enables the formation of large bodies of water and dense cloud cover
  • Promotes the growth of vegetation and the development of complex ecosystems
  • Results in a surface full of impact craters and extreme temperature variations
  • Leads to frequent and intense volcanic eruptions and tectonic activity

• What are the theories regarding the Moon's internal structure?

  The Moon's internal structure is thought to be differentiated, like Earth's, but much simpler. It is believed to consist of a small core, a mantle, and a crust. The core is thought to be primarily metallic, possibly composed of iron, and relatively small in comparison to Earth's. Surrounding the core is the mantle, which is believed to be made of minerals like olivine and pyroxene. The outermost layer is the crust, composed largely of anorthosite and other silicate materials. Seismic data from moonquakes and analysis of the Moon's gravity field have been crucial in developing these theories. There is also a hypothesis that the Moon's interior might still be partially molten, especially near the core.

  • Made entirely of a homogenous mixture of rock and metal
  • Differentiated into a small core, mantle, and crust
  • Composed of a single, thick layer of dust and regolith
  • Filled with large caverns and underground oceans

• What are the main minerals found on the Moon?

  The Moon's surface contains a variety of minerals, with the most abundant being plagioclase feldspar, pyroxene, and olivine. These minerals are primarily found in the lunar highlands and in the basaltic material of the lunar maria. Plagioclase feldspar, particularly anorthite, is a major component of the lunar crust and is prevalent in the highlands. Pyroxene and olivine are commonly found in the basaltic rocks that make up the lunar maria. The Moon also contains minor amounts of minerals such as ilmenite, armalcolite, and troilite. Recent missions have also suggested the presence of water ice in permanently shadowed regions near the poles.

  • Carbonates, sulfates, and halides
  • Plagioclase feldspar, pyroxene, and olivine
  • Quartz, gypsum, and calcite
  • Diamond, gold, and silver

• What is the Sea of Tranquility on the Moon known for?

  The Sea of Tranquility, or Mare Tranquillitatis, is one of the most famous features on the Moon, known primarily as the site of the first manned lunar landing by Apollo 11 in 1969. This mare, a large, dark basaltic plain, was chosen as the landing site for its relatively smooth and level terrain. The Sea of Tranquility is not a sea in the Earthly sense, as there is no liquid water on the Moon. Instead, it is an area filled with basaltic lava that solidified billions of years ago. The landing of Apollo 11 in this area marked a significant milestone in human space exploration, with Neil Armstrong and Buzz Aldrin becoming the first humans to walk on the Moon.

  • Being the largest impact crater on the Moon
  • Site of the first manned lunar landing by Apollo 11 in 1969
  • Known for its active volcanic eruptions
  • Hosting the highest mountain peak on the Moon

• What was the Lunar Reconnaissance Orbiter mission's objective?

  The Lunar Reconnaissance Orbiter (LRO) mission, launched by NASA in 2009, had several key objectives. Its primary goal was to map the Moon's surface in high resolution to aid in future lunar exploration missions. The LRO was tasked with identifying safe landing sites, locating potential resources, studying the lunar radiation environment, and providing measurements to understand the Moon's thermal and chemical properties. The mission also aimed to explore the Moon's polar regions, searching for evidence of water ice and assessing the Moon's topography and surface composition. The data collected by the LRO has been crucial in expanding our understanding of the Moon and planning for future manned and unmanned missions.

  • Mapping the Moon's surface in high resolution and studying the lunar environment.
  • Searching for signs of extraterrestrial life and analyzing the lunar soil for organic compounds.
  • Observing Earth from a lunar perspective to monitor environmental changes and natural disasters.
  • Testing new space travel technologies for future long-duration manned missions to Mars.

• How do the sizes of the Moon and Earth compare?

  The Moon is significantly smaller than Earth, both in terms of diameter and mass. The Moon's diameter is about 3,474 kilometers (2,159 miles), which is roughly one-fourth (about 27%) of Earth's diameter, which is about 12,742 kilometers (7,918 miles). When it comes to mass, the difference is even more pronounced. The Moon's mass is about 1.2% of Earth's mass. This size difference results in the Moon having weaker gravity, about 1/6th that of Earth's, which is why astronauts on the Moon experience much lighter conditions.

  • The Moon's diameter is about one-fourth of Earth's, and its mass is about 1.2% of Earth's.
  • The Moon is half the size of Earth, with a diameter about 50% that of Earth's.
  • The Moon is nearly as large as Earth, with a diameter about 75% that of Earth's.
  • The Moon and Earth are similar in size, with the Moon being slightly smaller.

• What are the potential resources on the Moon that could be utilized in future missions?

  Potential resources on the Moon that could be utilized in future missions include water ice, minerals, and solar power. Water ice, particularly at the lunar poles in permanently shadowed craters, is of high interest as it can potentially be used for life support (drinking water and oxygen) and fuel (hydrogen for rocket fuel). The lunar regolith (soil) contains minerals like ilmenite (which can be processed to extract iron, titanium, and oxygen), silica, and various metals. The Moon's surface also offers an environment for solar power generation, especially at the poles, where sunlight is nearly constant. Utilizing these resources could support sustained human presence on the Moon and aid in deeper space exploration.

  • Water ice for life support and fuel, minerals in the regolith for construction and manufacturing, and solar power for energy.
  • Rich deposits of gold and platinum, providing valuable materials for trade and economic growth.
  • Abundant fossil fuels and organic compounds, similar to those found on Earth.
  • A rare helium isotope, helium-3, for use in nuclear fusion reactors on Earth.

Torsten Edelmann (wonderplanets.de), CC BY-SA 2.5

About The Moon

The Moon, Earth's only natural satellite, is a fascinating celestial body that has captivated humans throughout history. Here are some key aspects that highlight its significance and characteristics:

Formation
The Moon is believed to have formed about 4.5 billion years ago, not long after Earth. The prevailing hypothesis is the giant-impact hypothesis, which suggests the Moon was created from the debris left over after a giant collision between Earth and a Mars-sized body named Theia.

Physical Characteristics
● Diameter: About 1/4 of Earth's, approximately 3,474 km.
● Gravity: 1/6th of Earth's, which affects the ability of astronauts to walk on its surface.
● Surface: The Moon's surface is covered with craters, mountains, and flat plains called maria (Latin for "seas"). These features are the result of meteoroid impacts and ancient volcanic activity.
● Atmosphere: The Moon has a very thin and weak atmosphere called an exosphere, which does not provide any substantial protection from the sun's rays or cosmic rays.

Synchronous Rotation
The Moon is tidally locked to Earth, meaning it rotates on its axis in exactly the same time it takes to orbit Earth. This results in the same side of the Moon always facing Earth.

Phases and Eclipses
The Moon goes through phases, from new Moon to full Moon and back, over a cycle that averages 29.5 days. Lunar and solar eclipses occur due to the alignments of the Earth, the Moon, and the Sun. A lunar eclipse happens when the Earth is directly between the Sun and the Moon, casting a shadow on the Moon. A solar eclipse occurs when the Moon passes between the Earth and the Sun, blocking the Sun’s light.

Influence on Earth
The Moon has a significant impact on Earth, including:
● Tides: The gravitational pull of the Moon causes the oceans to bulge, leading to high and low tides.
● Stabilization of Earth's Axial Tilt: It is believed that the Moon's gravitational influence helps stabilize Earth's axial tilt, which contributes to a relatively stable climate.

Exploration
The Moon has been the subject of human exploration both by manned Apollo missions, which brought 12 astronauts to its surface between 1969 and 1972, and by unmanned spacecraft from various countries. It remains of interest for future exploration and as a potential stepping stone for missions further into the solar system.

Cultural Significance
The Moon has held an important place in cultures around the world, influencing calendars, mythology, art, and literature. It continues to inspire wonder and scientific inquiry.

The Moon remains a source of fascination and study, providing insights into our solar system's history and the formation of celestial bodies. Its relatively untouched surface acts as a record of the solar system's history, offering clues to understand not just the Moon itself but also Earth and other planets.