Twice a year, in March and September, during an equinox, night and day are equal in length. On September 23, 2011 this signals the official start of fall.

Said another way, on these two days, the center of the sun passes directly over the equator and spends the same amount of time above and below the horizon at all locations on earth.

The 2010 September equinox occurs at 03:09 (or 3:09am) Coordinated Universal Time (UTC) on September 23, 2010. For locations in the US, including Lake Tahoe,  the equinox will occur in the evening of September 22, 2010.

The word "equinox" was derived from Latin term "æquinoctium" which, in turn, came from "æquus" (equal), and "nox" (night). The fall equinox is also known as: Alban Elfed, Autumn Equinox, Autumnal Equinox, Cornucopia, Feast of Avilon, Festival of Dionysus, Harvest Home, Harvest Tide, Mabon, Night of the Hunter, Second Harvest Festival, Wine Harvest, Witch's Thanksgiving, and the first day of autumn. In Old English, the language spoken circa 450 to 1100 CE, it was called "efnniht."

There is a rumor that surfaces twice a year at the time of the spring and fall equinoxes.  Many people believe that since the equinox is a time of balance where the daylight hours and nighttime hours are equal, that -- by some mystical force -- one can balance eggs on their end on these days. Some believe that one can only balance an egg within a few hours before or after the exact time of the equinox.

The Winter Solstice, the shortest day and longest night of the year (in the Northern Hemisphere) will occur in December. On that day, the center of the sun will touch the Tropic of Capricorn at 23 degrees south of the equator...the farthest south the sun travels. In many northern latitudes, the Winter Solstice is a day of rebirth because after that date the sun heads back north, relatively speaking. On our calendars, winter begins!

September and October are beautiful months in the Tahoe Region: mild days, cool nights, and a quiet feeling of peace and serenity.

Source for some of the material in this article: ReligousTolerance.org