Every year, twice a year, the earth is tilted just right relative to its path around the sun that we have exactly 12 hours of daylight and 12 hours of night. This is called an equinox and it happens in the spring (vernal equinox) on March 20 and in the fall (autumnal equinox) on September 22.
Eggs have long been associated with spring – a time of rebirth and new life. This is how eggs have become associated with Easter, a Christian spring holiday.
One of the most persistent misconceptions about eggs and the vernal equinox is that you can balance an egg on end ONLY at the exact moment of the equinox. The theory is that the gravitational pull of the sun is just right to hold up the egg. This is of course total nonsense.
Eggs can be balanced on any day (or night) of the year with one of two methods.
Method 1: Just the right egg
If you can find an egg that is just a little bit flat on the larger end and the yolk is exactly centered in the egg, you should be able to carefully balance the egg with no assistance. In order for an object to stay upright you must have the center of gravity, that is the center of where gravity pulls down on the object, over the base or whatever is holding it up. In the case of eggs, the yolk is the heaviest part of the egg and an off balance yolk can put the center of gravity off the balance point of the egg so it doesn’t stay up.
Does it matter if the egg is raw or hard boiled? Try it and see!
For most people, the center of gravity is near your belly button. You can only stay standing upright as long as your bellybutton is over your feet. This is why you can bend over when your back it against a wall. You will fall forward because your belly button doesn’t stay over your feet.
Method 2: A dash of salt
Make a small pile of salt. Put the egg on end in the middle of the pile. The tiny crystals of salt will make a small pedestal to balance the egg on end. Gently blow away the extra salt and voila! You have an egg balanced on its end.
If you balance an egg this spring, be sure to post a photo on the STEMplay Facebook page!