Spring Equinox 2011

Cover of John Hassell's CD "Vernal Equinox"

Today, March 20, at 7:21 P.M. EDT will be the vernal, or spring equinox.

An equinox occurs twice a year, spring and fall, when the tilt of the Earth’s axis is inclined neither away from nor towards the Sun, and the Sun is vertically above a point on the Equator.

Some people confuse equinoxes with the solstices that mark the change of the seasons to summer and winter for us. (see my other solstice posts)

Though we commonly think of spring as warmer weather, the seasonal change has everything to do with the changing sunlight determined by the tilt of the Earth’s axis.

My Old Farmer’s Almanac tells me that our little planet during a year revolves completely around the Sun spinning top-like on that invisible axis. The North Pole and South Pole are the top and bottom and the axis is tilted at a 23.5° angle away from the Sun during winter in our Northern Hemisphere. During our summer, it’s the opposite.

That imaginary equator line divides  Earth into the Northern and Southern Hemispheres. The seasons are the opposite in the Southern Hemisphere.

Summer in the Northern Hemisphere begins on or around June 21.  It’s early to be thinking summer, but that will kick in when the Sun is directly above an another imaginary line 23.5° north of the equator called the Tropic of Cancer.

Equinox comes from the Latin aequus (equal) and nox (night) because the night and day are approximately equal in length at these events. Equinoxes occur around March 20/21 and September 22/23 each year.

Unlike our Western calendar, the traditional East Asian calendars divide a year into 24 solar terms. That means that the equinoxes then mark the middle of the spring and autumn seasons.

In Japan, Vernal Equinox Day is an official national holiday and is spent visiting family graves and holding family reunions. This year, with the earthquake and tsunami having just occurred, the day will no doubt have a changed, perhaps heightened, significance.

Wiccans and many other Neopagans hold religious celebrations of “Ostara” on the spring equinox.

The word March comes from the association of this time with the Roman god Mars. (The Roman goddess of war was Bellona, but her day is in June. Go figure.)  Mars is similar to the Greek Ares (as in Aries, the zodiac sign of this month), Tiu or Tiwaz of Central and Northern Europe, Teutates of the Celts, and Tyr of the Norse.

In case you get into a betting situation at the local watering hole, remember daytime and nighttime on the equinoxes are not really equal. Well, within a few days of each equinox, there is a day with nearly equal daytime and nighttime, but that depends on your latitude. Chances are those folks have been drinking and can’t identify their latitude, so just make up a reasonable number and you can win the bet.