About: Autumn Equinox

The September equinox is the moment when the Sun appears to cross the celestial equator, heading southward. Due to differences between the calendar year and the tropical year, the September equinox can occur at any time between September 21 and 24. At the equinox, the Sun as viewed from the equator rises due east and sets due west. Before the Southward equinox, the Sun rises and sets more northerly, and afterwards, it rises and sets more southerly. The equinox may be taken to mark the end of summer and the beginning of autumn in the Northern Hemisphere, while marking the end of winter and the start of spring in the Southern Hemisphere.