Summer's Over In The Morning

Autumnal Equinox
More dark than daylight coming up!

In the language of science, an equinox is either of two points on the celestial sphere where the ecliptic and the celestial equator intersect. For the rest of us, it's one of two times a year when the sun crosses the equator, and the day and night are of approximately equal length.

At the autumnal equinox (Sept. 23, 2007, 5:51 A.M. EDT), the sun appears to cross the celestial equator, from north to south; this marks the beginning of autumn in the Northern Hemisphere.
Link (from Infoplease.com)