Eclipse

Introduction
Phenomena observed during eclipses
- Lunar eclipse phenomena
- Solar eclipse phenomena
The geometry of eclipses, occultations, and transits
- Eclipses of the Sun
- Eclipses of the Moon
- Eclipses, occultations, and transits of satellites and other objects
The frequency of solar and lunar eclipses
- Cycles of eclipses
- Prediction and calculation of solar and lunar eclipses
Eclipse research activities
- Solar research
  - Discovery of helium
  - Support for the general theory of relativity
  - Temperature of the corona
- Lunar research
Transits of Mercury and Venus
Occultations
Eclipsing binary stars
Eclipses in history
- Literary and historical references
  - Chinese
  - Assyrian
  - Babylonian
  - Jewish
  - Greek
  - Roman
  - Medieval European
  - Medieval Islamic
- Uses of eclipses for chronological purposes
- Uses of eclipses for astronomical purposes

References & Edit History Related Topics

Images, Videos & Interactives

Map showing the path of the total solar eclipse on August 12, 2026, crossing Greenland, Iceland, northern Russia, the Atlantic Ocean, Spain, and Portugal.

Diagram showing a lunar eclipse with the Sun on the left, Earth in the center casting a shadow, and the Moon passing through Earth's umbra (total shadow) and penumbra (partial shadow).

Learn why there is not a solar eclipse every month

Diagram showing the stages of a total and partial solar eclipse, with the Moon moving across the Sun. Each phase is illustrated step-by-step, from first contact through maximum coverage to last contact.

At a Glance

eclipse summary

Quizzes

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

From which edge does Earth’s shadow usually begin covering the Moon during a lunar eclipse?
How are solar eclipses different from lunar eclipses?
How can astronomers predict the date and path of a solar eclipse?
How can solar retinopathy result from looking at the Sun during an eclipse?
How do Baily’s beads form during a total solar eclipse?
How does a lunar eclipse occur when Earth casts its shadow on the Moon?
How does a penumbral lunar eclipse differ from a partial lunar eclipse?
How does a pinhole projection allow people to observe a solar eclipse indirectly?
How does a solar eclipse occur when the Moon passes between Earth and the Sun?
How does a total lunar eclipse differ from a partial lunar eclipse?
How does a total solar eclipse differ from a partial solar eclipse?
How does the 5-degree tilt of the Moon’s orbit affect eclipses?
How does the Moon’s distance from Earth affect whether a solar eclipse is total or annular?
How does the Sun’s distance from Earth affect whether a solar eclipse is total or annular?
How does the lunar surface change temperature during a lunar eclipse?
How does the saros cycle help predict eclipses?
How does the umbra differ from the penumbra during an eclipse?
How long can totality last during a total solar eclipse?
How many solar eclipses can occur in a calendar year?
How often can one location experience a total solar eclipse?
How often do solar eclipses occur somewhere on Earth?
What is the path of totality during a total solar eclipse?
What role do the Moon’s orbital nodes play in solar and lunar eclipses?
Which ancient civilizations kept important records of eclipses?
Why are penumbral lunar eclipses difficult to notice?
Why are there no annular lunar eclipses?
Why can a lunar eclipse be seen from much more of Earth than a solar eclipse?
Why can a lunar eclipse happen only at a full moon?
Why can a solar eclipse happen only at a new moon?
Why can a total lunar eclipse last much longer than a total solar eclipse?
Why can a total solar eclipse be seen from only a narrow path on Earth?
Why can an annular eclipse occur when the Moon is farthest from Earth?
Why can the brightness and color of a totally eclipsed Moon vary from one eclipse to another?
Why do solar and lunar eclipses not occur every month?
Why do solar eclipses seem less frequent than lunar eclipses even though they occur more often worldwide?
Why do the Sun and Moon appear nearly the same size in Earth’s sky?
Why does a total lunar eclipse not make the Moon completely dark?
Why does the Moon often look red during a total lunar eclipse?
Why is it dangerous to look directly at the Sun during a partial solar eclipse?
Why is the Sun’s corona visible during totality?
Why is the edge of Earth’s umbra blurry during a lunar eclipse?

Science Astronomy

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External Websites

European Space Agency - What is an eclipse?
K12 LibreTexts - Eclipses
Universities of Wisconsin Open Ed Network - Survey of Astronomy - Eclipses of the Sun and Moon
NASA - Eclipses

Britannica Websites

Articles from Britannica Encyclopedias for elementary and high school students.

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

Eclipse

astronomy

Written by

Jakob Houtgast

Associate Professor of Astronomy, Astronomical Institute, State University of Utrecht, The Netherlands. Coauthor of Photometric Atlas of the Solar Spectrum.

Jakob HoutgastAll

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. 9, 2026 •History

Eclipse, in astronomy, complete or partial obscuring of a celestial body by another. An eclipse occurs when three celestial objects become aligned. From the perspective of a person on Earth, the Sun is eclipsed when the Moon comes between it and Earth, and the Moon is eclipsed when it moves into the shadow of Earth cast by the Sun. Eclipses of natural satellites (moons) or of spacecraft orbiting or flying past a planet occur as...

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