The Moon is Earth ’s sole natural satellite and nearest large celestial body. It is a spherical rocky body, probably with a small metallic core, revolving around Earth in a slightly eccentric orbit at a mean distance of about 384,000 km (238,600 miles). Its equatorial radius is 1,738 km (1,080 miles). Because of the Moon’s small size and mass, its surface gravity is only about one-sixth of Earth’s.

Moon

Table of Contents

References & Edit History Related Topics

Images, Videos & Interactives

Interactive: A Tour of the Moon's Landmarks.

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

geometry and motions of the Earth-Moon system

Learn five facts about the astronomical phenomenon that occurs when the Moon passes between the Sun and Earth

Discover how the Moon's equal periods of rotation and revolution affect its orientation toward Earth

For Students

Moon summary

Read Next

Galileo spacecraft image of the Moon taken on December 7, 1992. The distinct bright ray crater at the bottom of the image is the Tycho impact basin. The dark areas are lava rock filled impact basins: Oceanus Procellarum (on the left), Mare Imbrium (cont'd

5 Things People See in the Moon

(Buzz Aldrin) stands next to the U.S. flag at Tranquility Base on the Moon during NASA's Apollo 11 mission, July 20, 1969. Aldrin's forward-leaning stance was the normal resting position of an astronaut wearing the life-support pack.

Moon Landing: Just the Facts

Solar system illustration. (Sun; planets)

A Model of the Cosmos

solar eclipse, sun, moon, astronomy, space

How Do You Tell the Difference Between Total, Annular, Solar, and Lunar Eclipses?

Where Did the Moon Come From?

Discover

Person paying with a credit card using a credit card terminal. Cashless payment, credit card reader

What Is a Cashless Society and How Does It Work?

African Americans demonstrating for voting rights in front of the White House as police and others watch, March 12, 1965. One sign reads, "We demand the right to vote everywhere." Voting Rights Act, civil rights.

Timeline of the American Civil Rights Movement

A Factory Interior, watercolor, pen and gray ink, graphite, and white goache on wove paper by unknown artist, c. 1871-91; in the Yale Center for British Art. Industrial Revolution England

Inventors and Inventions of the Industrial Revolution

Shadow of a man holding large knife in his hand inside of some dark, spooky buiding

7 of History's Most Notorious Serial Killers

Albert Einstein in Washington, D.C. c. 1921-1923. Physicist

The Solar Eclipse That Made Albert Einstein a Science Celebrity

General Pershing's troops moving into Mexico in 1917 during World War I.

Timeline of World War I

Groups of depositors in front of the closed American Union Bank, New York City. April 26, 1932. Great Depression run on bank crowd

Causes of the Great Depression

Science & Tech

Moon

Q: Should humans colonize the Moon?

Space colonization, on the Moon or elsewhere, is widely debated. Some argue that humans have a moral duty to save our species from extinction, and space colonization is one way of doing so. Others argue that living in space is science fiction and that we should concentrate on improving life on Earth instead of potentially ruining another planet or moon. For more on the debate about colonizing space, visit ProCon.org .

Earth’s satellite

Written by James D. Burke

Fact-checked by The Editors of Encyclopaedia Britannica

Last Updated: Apr 14, 2024 • Article History

Recent News

Apr. 13, 2024, 5:55 AM ET (BBC)

Engineers in Oregon train dog robot to walk on Moon

Apr. 12, 2024, 10:50 AM ET (USA Today)

Moon not visible when light side faces away from Earth | Fact check

What is the Moon?

Should humans colonize the Moon?

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. The Moon’s desolate beauty has been a source of fascination and curiosity throughout history and has inspired a rich cultural and symbolic tradition. In past civilizations the Moon was regarded as a deity, its dominion dramatically manifested in its rhythmic control over the tides and the cycle of female fertility. Ancient lore and ...(100 of 10458 words)

Access the full article

Help support true facts by becoming a member.