Science & Tech

autumnal equinox

astronomy
verifiedCite
While every effort has been made to follow citation style rules, there may be some discrepancies. Please refer to the appropriate style manual or other sources if you have any questions.
Select Citation Style
Feedback
Corrections? Updates? Omissions? Let us know if you have suggestions to improve this article (requires login).
Thank you for your feedback

Our editors will review what you’ve submitted and determine whether to revise the article.

Print
verifiedCite
While every effort has been made to follow citation style rules, there may be some discrepancies. Please refer to the appropriate style manual or other sources if you have any questions.
Select Citation Style
Feedback
Corrections? Updates? Omissions? Let us know if you have suggestions to improve this article (requires login).
Thank you for your feedback

Our editors will review what you’ve submitted and determine whether to revise the article.

seasonal configuration of Earth and Sun
seasonal configuration of Earth and Sun
Related Topics:
Wicca
autumn
equinox
March
September

autumnal equinox, two moments in the year when the Sun is exactly above the Equator and day and night are of equal length; also, either of the two points in the sky where the ecliptic (the Sun’s annual pathway) and the celestial equator intersect. In the Northern Hemisphere the autumnal equinox falls about September 22 or 23, as the Sun crosses the celestial equator going south. In the Southern Hemisphere the equinox occurs on March 20 or 21, when the Sun moves north across the celestial equator.

According to the astronomical definition of the seasons, the autumnal equinox also marks the beginning of autumn, which lasts until the winter solstice (December 21 or 22 in the Northern Hemisphere, June 20 or 21 in the Southern Hemisphere).

The orbits of the planets and other elements of the solar system, including asteroids, Kuiper belt, Oort cloud, comet
Britannica Quiz
Space Odyssey
The Editors of Encyclopaedia Britannica This article was most recently revised and updated by Meg Matthias.