Posted by Davin Flateau on 20 Mar 2006 at 12:21 pm.
Filed under Astronomy.
Happy vernal equinox! Time to break out the Nox Nog, and raise a glass to the first day of spring. Just in time for a snow storm to dump feet of snow here in Kansas. I can smell the snowblower exhaust and road salt wafting through the fragrant spring air already.
The term equinox, latin for “equal night”, hints at what’s going on today. On only two days, the vernal (spring) and autumnal (fall) equinoxes, the alignment of the earth’s tilt and its orbit around the sun allows an equal amount of daylight and night for all the places on the earth (if you want to get really technical, there’s slightly more day than night today due to the fact the sun’s a round disc and the effects of atmospheric refraction).
This is one of those classically hard-to-explain brain teasers in astronomy that you really need a good diagram for, but it’s worth hanging in, since it ties into the explanation of our seasons.
Our earth rotates on its axis, spinning quite happily, completing one whole day every 24 hours. That spinning ball is also travelling around the sun in a circle, but the spinning earth is titled about 23.5 degrees, and always pointing in the same direction in the sky during our trip around the sun. Because of this tilt, we experience differing amounts of day and night during different parts of the year, depending on where on the earth you are. Only two times in our orbit around the sun is the tilt “nullifieid”, creating equal day and night for those of us who are trapped on our spinning world.
Also because of earth’s tilt, the sun’s angle to the surface changes, affecting how much energy different parts of the earth receive. This creates the seasons: summers result from more hours of daylight with more direct sunlight, and winters from less hours of daylight with less direct sunlight. Check out a really good basic explanation, and more in depth one.
You may have heard your grandfather or some other mysterious relative spin an archane tale about how there’s something special about this day on earth. Somehow the normal laws of physics go on vacation for a day, allowing you to balance an egg on its long side on the vernal equinox.
Well, as many eggless breakfasts will attest, this is just one of those crazy stories that gets passed down for who knows what reason. Our friend Phil Plait over at badastronomy.com has a good article where he actually stands eggs on their end! But in October.
How did this rumor get started? Eggs have long been associated with the spring, fertility and new life. Somehow, somewhere the astronomical spring collided with the cultural symbol, and the crazy pseudo-scientific superstition was born.
It could be a harmless myth, or it could be just part of an insidious conspiracy led by the Egg Council this time of year to drive us all insane.
