What is the Fall Equinox?

With Friday the last day of summer 2012, fall is just hours away—and that means another fall (or autumnal) equinox, is coming on Saturday.

But what is the autumnal equinox? Most people don't quite know, so let Gilroy Patch serve as the great explainer for all things equinoctial.

Equinoxes fall on the halfway point between solstices and occur, according to the Washington Post, "when the sun crosses the equator and day and night are of roughly equal length, everywhere in the world."

The nearly equal 12 hours of light and darkness can be attributed to the Earth's lack of an axial tilt on the day of the equinox. In fact, the word equinox is derived from the Latin words aequus, meaning equal, and nox, meaning night.

In Gilroy on the autumnal equinox, according to sunrisesunset.com, the sun will come up at 6:56 a.m. and set at 7:05 p.m. As you notice, that is not actually a perfect 12 hours of light and darkness. As timeanddate.com reports, this is because "the day is slightly longer in places that are further away from the equator, and because the sun takes longer to rise and set in these locations. Furthermore, the sun takes longer to rise and set farther from the equator, because it does not set straight down—it moves in a horizontal direction."

The exact moment of the autumnal equinox this year is 2:49 p.m. Coordinated Universal Time, or 7:49 a.m. Pacific Daylight Time. You might be hard pressed to find a celebration at that hour, but don't let that stop you from indulging in fall festivities come the weekend.

See ya next year, summer. Hello fall, and happy autumnal equinox!