Moon

Introduction & Top Questions
Distinctive features
Principal characteristics of the Earth-Moon system
Motions of the Moon
The atmosphere
The lunar surface
- Large-scale features
- Effects of impacts and volcanism
- Small-scale features
- Lunar rocks and soil
  - General characteristics
  - Main groupings
The lunar interior
- Structure and composition
- Internal activity of the past and present
Origin and evolution
Lunar exploration
- Early studies
- Exploration by spacecraft
  - First robotic missions
  - Apollo
  - Return to the Moon
- Mission results
- Lunar resources

References & Edit History Related Topics

Images, Videos & Interactives

Interactive: A Tour of the Moon's Landmarks.

Infographic titled Features of the Moon's Surface compares the near side and far side of the Moon. Labels identify dark, lava-filled maria; older, brighter highlands; impact craters; and lunar basins larger than 186 miles in diameter.

Look at the 3D map of the Moon as taken by the Clementine spacecraft

Diagram showing Earth and Moon with labeled axes, orbital planes, and the barycentre, illustrating how both bodies orbit a shared center of mass rather than just the Earth.

Why does the Moon always face Earth the same way?

At a Glance

Moon summary

Quizzes

View of the Andromeda Galaxy (Messier 31, M31).

Astronomy and Space Quiz

Model of a molecule. Atom, Biology, Molecular Structure, Science, Science and Technology. Homepage 2010 arts and entertainment, history and society

Science Quiz

The orbits of the planets and other elements of the solar system, including asteroids, Kuiper belt, Oort cloud, comet

Space Odyssey

Saturn. Saturn and its rings. Second largest planet of the solar system. Space Art

Planets and the Earth’s Moon

Nicolaus Copernicus. Nicolas Copernicus (1473-1543) Polish astronomer. In 1543 he published, forward proof of a Heliocentric (sun centered) universe. Coloured stipple engraving published London 1802. De revolutionibus orbium coelestium libri vi.

All About Astronomy

Related Questions

How are the phases of Earth seen from the Moon related to the Moon’s phases seen from Earth?
How could lunar ice be turned into rocket propellant?
How could lunar ice be used to support astronauts living on the Moon?
How did Apollo rock samples change scientists’ understanding of lunar history?
How did LCROSS confirm water ice near the Moon’s south pole?
How did lunar maria form?
How do moonquakes differ from earthquakes?
How does a lunar eclipse occur?
How does a solar eclipse occur?
How does lunar libration allow observers on Earth to see more than half of the Moon?
How does the Moon’s distance from Earth determine whether a solar eclipse is total or annular?
How does the Moon’s elliptical orbit change its distance from Earth?
How does the Moon’s weak gravity affect how high astronauts can jump?
How far is the Moon from Earth?
How is the Moon slowly moving away from Earth?
How long does the Moon take to orbit Earth?
How many astronauts walked on the Moon during the Apollo program?
What are the Moon’s eight phases in order?
What creates the face-like pattern called the Man in the Moon?
What did Chandrayaan-1 discover about water molecules on the Moon?
What did the Ranger spacecraft missions reveal about the lunar surface?
What evidence shows that the Moon was volcanically active long ago?
What evidence suggests that the Moon once had a magnetic field?
What is the South Pole–Aitken Basin like?
What role did Michael Collins have during the Apollo 11 landing?
What role did the Mars-sized body Theia play in the giant-impact hypothesis?
What were the most important achievements of the Soviet Luna missions?
Who were the first people to walk on the Moon during Apollo 11?
Why are lunar days extremely hot and lunar nights extremely cold?
Why are most lunar mountains rounded rather than steep and sharp?
Why could cold lunar polar regions be useful sites for infrared telescopes?
Why could lunar polar regions provide nearly continuous solar power?
Why did the coaccretion theory fail to explain the Earth-Moon system?
Why did the fission theory of lunar formation lose support?
Why do permanently shadowed craters exist at the Moon’s poles?
Why do solar and lunar eclipses not happen every month?
Why do the lunar maria look dark when viewed from Earth?
Why does Earth have fewer visible impact craters than the Moon?
Why does a full moon occur when the Moon is opposite the Sun?
Why does a new moon occur when the Moon is between Earth and the Sun?
Why does the Moon always show nearly the same side to Earth?
Why does the Moon appear to change shape during a month?
Why does the Moon have no seasons?
Why does the Moon shine in the night sky?
Why is the capture theory of lunar formation considered unlikely?
Why is the time from one full moon to the next longer than the Moon’s orbital period?
Why is water ice found in some lunar polar craters?
Why might lunar soil be useful for shielding Moon habitats from radiation?
Why was Luna 3 important for studying the Moon?
Why were Lunar Orbiter photographs important for the Apollo program?
What does the pink moon mean?
When is the pink moon?

Science Astronomy

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External Websites

Space.com - Moon facts: Fun information about the Earth's moon
American Association for the Advancement of Science - Space: Science and Technology - Volcanism and Deep Structures of the Moon
Physics LibreTexts - The Moon
NASA - Moons of Our Solar System
NASA Science - Solar System Exploration - Earth's Moon
The Planets - Moon Facts
Live Science - Why Does the Moon Have Phases?

Britannica Websites

Articles from Britannica Encyclopedias for elementary and high school students.

Moon - Children's Encyclopedia (Ages 8-11)
Moon - Student Encyclopedia (Ages 11 and up)

Moon

Earth’s satellite

Written by

James D. Burke

Member, Technical Staff, Spacecraft Systems Engineering, Jet Propulsion Laboratory, California Institute of Technology, Pasadena. Technical Editor The Planetary Report.

James D. Burke

Fact-checked by

Britannica Editors

Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree....

Britannica Editors

Last updated

Nov. 14, 2026 •History

Moon, Earth’s sole natural satellite and nearest large celestial body. Known since prehistoric times, it is the brightest object in the sky after the Sun. It is designated by the symbol ☽. Its name in English, like that of Earth, is of Germanic and Old English derivation. Did You Know? NASA announced it was planning to build a nuclear reactor on the Moon by 2030. The Moon’s desolate beauty has been a source of fascination...

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