Autumnal Equinox

...for us in the Northern Hemisphere, of course.  Finally!  Summer is over!  I don't care if it IS 95 degrees outside today, SUMMER IS OVER!!  For our Aussie friends and everyone else south of the Equator, winter is giving way to spring. 

September Equinox

There are two equinoxes every year – in September and March – when the sun shines directly on the equator and the length of day and night is nearly equal. Seasons are opposite on either side of the equator, so the equinox in September is also known as the "autumnal (fall) equinox" in the northern hemisphere. However, in the southern hemisphere, it's known as the "spring (vernal) equinox".

      September Equinox 2012:

September 22,
14:49 (or 2.49pm) UTC

• When is the September Equinox 2012 in my city?
• Equinoxes & Solstices 2000-2049

Why is it called equinox?

On the equinox, night and day are nearly exactly the same length – 12 hours – all over the world. This is the reason it's called an "equinox", derived from Latin, meaning "equal night". However, even if this is widely accepted, it isn't entirely true. In reality equinoxes don't have exactly 12 hours of daylight.

The September equinox occurs the moment the sun crosses the celestial equator – the imaginary line in the sky above the Earth’s equator – from north to south.
This happens either on September 22, 23, or 24 every year. On any other day of the year, the Earth's axis tilts a little away from or towards the Sun. But on the two equinoxes, the Earth's axis tilts neither away from nor towards the Sun, like the illustration shows.

June Solstice | December solstice | March equinox

Or, we could think about the equinox in Biblical terms:  we're entering the GATES OF HELL!!

The fall equinox symbolizes the gates to hell. Satan rules during the lower half of the sun cycle in fall and winter. The sun dies in the pits of hell at the winter solstice. At night the sun was believed to go under the world, so we have the term "underworld".

from "The Unspoken Bible"