Definition:Equinox/Autumnal
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Definition
The autumnal equinox is the equinox at which the sun crosses the celestial equator from north to south.
In the northern hemisphere this crossing occurs sometime around $23$ September.
Also known as
The autumnal equinox is also known as the September equinox or the fall equinox.
The term southward equinox can also be seen in contexts requiring hemisphere neutrality.
Also see
- Results about equinoxes can be found here.
Linguistic Note
The term autumnal equinox derives from word autumn, which is British English for (the season of) fall, and aequinoctium, from aequus meaning equal and nox meaning night.
Sources
- 1998: David Nelson: The Penguin Dictionary of Mathematics (2nd ed.) ... (previous) ... (next): autumnal equinox
- 1998: David Nelson: The Penguin Dictionary of Mathematics (2nd ed.) ... (previous) ... (next): equinoxes (equinoctial points)
- 2008: David Nelson: The Penguin Dictionary of Mathematics (4th ed.) ... (previous) ... (next): autumnal equinox
- 2008: David Nelson: The Penguin Dictionary of Mathematics (4th ed.) ... (previous) ... (next): equinoxes (equinoctial points)