September 22 - Autumnal Equinox
The September equinox (or Southward 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 from the 21st to the 24th day of September.
At the equinox, at the equator, the Sun rises directly in the East and sets directly in the West. Before the Southward equinox, the Sun rises and sets more to the North, and afterwards, it rises and sets more to the South.
The equinox may be taken to mark the end of summer and beginning of autumn (autumn equinox) in the Northern Hemisphere, while marking the end of winter and the start of spring (vernal equinox) in the Southern Hemisphere. (Information from Wikipedia) | 
