September equinox

2014 Sep 23

On 23 September, the Sun will pass over the celestial equator on its southward journey, marking the beginning of autumn in the northern hemisphere and of spring in the southern hemisphere.

On this day, the Sun will be above the horizon for almost exactly twelve hours at all latitudes. The word equinox is derived from the fact that on this day, all places on Earth have equal hours of daylight and night time.