September 23 2014 is the September Equinox (or also known as the Southward equinox). This is the time when the sun appears to cross the celestial equator, heading southward.
During the equinox, the sun rises directly in the east and sets directly in the west. Before the Southward equinox, the sun rises and sets more and more to the north, and afterwards, it rises and sets more and more to the south.
In the Northern Hemisphere the September equinox is known as the autumnal equinox. In the Southern Hemisphere it is known as the vernal or spring equinox.
An equinox occurs twice a year. The word’s oldest meaning is 'the day when daytime and nighttime are approximately equal in duration', and derives from the Latin aequus (equal) and nox (night).