eclipse year

astronomy

Written by

The Information Architects of Encyclopaedia Britannica

Last updated

June 25, 2026

Quick Summary

An eclipse year is the interval between successive conjunctions of the Sun with the same node of the Moon's orbit. This period is approximately 346.62 sidereal days. Eclipses, both solar and lunar, occur when the Moon is near one of the nodes where its orbital plane intersects the ecliptic (Earth's orbital plane around the Sun).12

Solar eclipses happen at new moon, and lunar eclipses at full moon. However, not every new or full moon results in an eclipse because the Moon's orbit is tilted about 5° relative to the ecliptic. For an eclipse to occur, the Moon must be near a node. Solar eclipses are visible from limited areas on Earth, while lunar eclipses can be seen from any part of Earth where the Moon is above the horizon.2

Summary created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

3 Britannica Sources

Ask Britannica AI about this topic

Britannica doesn't have a full article on this topic, so we've curated a list of our relevant coverage.

eclipse
Prediction and calculation of solar and lunar eclipses
…the nodes is termed an eclipse year, and, since the Moon’s node moves so as to meet the advancing Sun, this interval is about 18.6 days less than a tropical (or ordinary) year.
Read More
…the nodes is termed an eclipse year, and, since the Moon’s node moves so as to meet the advancing Sun, this interval is about 18.6 days less than a tropical (or ordinary) year.
Read More