Autumn equinox - first day of fall
Autumn equinox! Fall begins in the Northern Hemisphere on September 22. The sun is overhead at the equator in its journey south. Days and nights are equal, 12 hours of daylight and 12 hours of darkness everywhere. The sun rises due east and sets due west everywhere on earth.
As the Northern Hemisphere tilts away from the sun, the sun appears lower in our sky. The sun's rays hit us less directly, and the top half of the globe cools down.
5 major circles of latitude: Arctic Circle. Tropic of Cancer. Equator. Tropic of Capricorn. Anarctic Circle.
September equinox @ EarthSky http://earthsky.org/astronomy-essentials/everything-you-need-to-know-about-the-autumnal-equinox-of-2012