The September Equinox, also known as the Autumnal Equinox in the Northern Hemisphere, occurs when the sun crosses the celestial equator.
The term "equinox" comes from the Latin words "aequus" (equal) and "nox" (night), implying the balance of around 12 hours of day and 12 hours of night.
This year it is happening at 12:43 UTC on September 22.
The equinox plays a key role in the astronomical calendar, marking one of the two points in the year when the sun is directly above the equator, leading to changing seasons.
The September Equinox signifies a shift in weather patterns, as temperatures begin to cool in the Northern Hemisphere, signaling the arrival of winters.
Many cultures celebrate the equinox with festivals and rituals. The autumn equinox is also linked to harvest festivals in various cultures
Lastly, many species begin their migration or breeding cycles in response to the changing length of daylight and temperature.