Friday, March 20, 2009

Equinox Means Balanced Light

Equinox Means Balanced Light, Not Balanced Eggs
by Von Del Chamberlain

Note: The 2004 vernal equinox will occur at 11:49 p.m. MST, 19 March 2004, when spring begins in the Northern Hemisphere.
EQUINOX: What charm this word has! For some, it seems to infer magical balance in the universe, an exaggeration that has escalated over time. Actually it just refers to the two times each year when the Sun crosses the celestial equator resulting in day and night being of equal length. This one element of equalization has resulted in a mythology that tells us more about how gullible we tend to be than about how we apply science to our lives.

Here is a case in point that comes into the news nearly every year. "Eggs can be stood on end at the equinox." Some will go on to say that this can happen only for an hour or two centered on the exact time of equinox. That sounds like science, but it isn't. For hundreds of years--some say thousands--it had been said in China that this phenomenon occurs at the moment winter ends and spring begins. But wait a minute! According to the Chinese this transition occurred at a variable time each year, determined partly by the Chinese lunar month, usually in early February. This is an example of the cross-quarter concept of the transition of seasons.

Then more recently, no one seems to know just when, this whole idea got transferred to the time of the vernal equinox. Along with this, all sorts of ridiculous statements got into the press, such as that Albert Einstein had doubted that eggs could be stood on end and that the Smithsonian didn't believe it either. You are apt to read or hear in the news that this phenomenon ONLY occurs at the equinox. You might see photographs of people doing it, yet--and this is the astonishing part--no one seems to ever raise the question as to whether or not it has been tried at other times.

I have tried it, at various times of year, just to have experiential proof that goes along with some understanding of physics, and to apply principles of science that suggest it is foolish to accept things that can easily be tested without testing them. Standing an egg on end on a hard and smooth surface, such as a kitchen counter top, requires care and patience, but it can be done any time of year.

So how did the idea that an egg could only be stood on end at the equinox get started? It began with something that has been carefully learned over a very long time, that after long months of winter, when weather is rapidly improving, we reach the time when the Sun is in the sky for half the day. Since we have half day and half night, people can not seem to resist adding other things to emphasize the balance they feel at this wonderful time of year.

Here is a tongue-in-cheek hypothesis of how this could have come about. Easter is celebrated on the first Sunday after the first full moon following the date of the vernal equinox. Thus, Easter can be just a few days after the equinox. Springtime, the Moon, resurrection, Easter and eggs, along with a lot of other things involving fertility, life and death, have become intertwined. Even the rabbit, a most prolific symbolism of fertility, has gotten into the picture. Imagine, then, an Easter Bunny's helper getting ready for Easter on the day of the equinox. The eggs are out and ready to boil before painting. Having heard that an egg could not be stood on end, our equinox scientist decided to give it a try. It was difficult, but all of a sudden it happened. In the spirit of the season, thinking this might have something to do with the balance of day and night, our unknown perpetrator quickly told others who were close by, starting an egg-standing on-end
frenzy. One call to the right media representative quickly cast the "discovery" in print never to be repealed, no matter what.

Each year, we, on planet Earth, cruised through the part of our orbit around the Sun that defines the vernal equinox in late March. At that moment, at a longitude along the equator where it was mid-day, the Sun crosses through the zenith, directly overhead. For people everywhere on Earth, the Sun reached the place in its daily movement across the sky that marks the middle of its change in paths throughout the year. Although this is special, it does not represent any particular balance of forces.

The underlying assumption relating to standing eggs on end is that there must exist some special gravitational balance. No such thing occurs at equinox time. Concerning gravitational effects, here are a few things to ponder. (1) Earth's orbit is elliptical, not circular. Thus, there is a slightly stronger force between Earth and Sun when we are closest to the Sun in January, and slightly less force when we are farther out in July. (2) Tidal forces on Earth are caused mostly by the Moon and Sun, and these two bodies nearly align each month at new moon and full moon, being strongest twice each year when eclipses occur, the two "eclipse seasons." Currently our eclipse seasons are in the months of March/April and September/October, but this changes constantly as the years go by. (3) Earth is not spherical, so that some places on Earth are nearer to our planet's center of gravity than are others. (4) There are other forces that are smaller, yet significant,
involving the pull of gravity from the other planets, and for that matter even from distant stars. I list these things to remind us that for anything we want to consider, there are many factors and never ever the perfect balance we might wish for, and there is no special gravitational balance at equinox time.

Getting back to our topic, even though the situation is complex, the most dominant force of gravity is the one between Earth and egg, the weight of the egg, the force pulling the egg to the counter top. All the variations listed above are negligible for the experiment of standing eggs on end.

If you want to prove this for yourself, take a fresh, uncooked, egg and hold it with the larger end resting on a table or counter top. Wait for the fluid content of the egg to settle, then carefully test the balance. Be patient as you find the point where you can ever so gently let it go to remain standing on end. If you want the experiment to be complete, do it at various times of year. Finally, next time you hear claims that sound miraculous, look for ways of testing before accepting.

The coming of spring, marked by the passage of the Sun from the Southern to the Northern Hemisphere of the sky, accompanied by the melody of awakening life around us, is quite enough of a "miracle" without being the singular time when eggs balance on end. Vernal equinox! The time when the Sun reappears at the north pole, after being away for six months. The time when the Sun crosses the zenith for equatorial people. The middle-time when everyone feels vitalized by the most rapid climatic changes of the year.

This article was modified from the original to serve as an information source for all vernal equinox events.

For more equinox insights (and some pictures of balancing eggs) visit Phil Plait's Bad Astronomy site.

Another good article is Phil's What Causes the Seasons?

Also available at the U.S. Naval Observatory's site is an article on the Length of Day and Night at the Equinoxes and UCAR has a nice explaination of the equinox.

And finally the Science Alliance has conducted egg balancing experiments with teachers.

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