The principle of erecting eggs on the vernal equinox:

On the day of the vernal equinox, day and night are equally divided in the northern and southern hemispheres. The earth's axis, which is tilted at 66.5 degrees, is in a force relative to the earth's orbital plane around the sun. At the same time, the earth's magnetic field is also relatively balanced, so the eggs stand best.

There are many protrusions about 0.03 mm high on the eggshell. The three protrusions can form a triangular plane. If the center of gravity of the egg passes through this triangle, the "erect egg" can be achieved.