As Earth revolves around the Sun, there are two moments each year when the Sun is exactly above the equator. These moments — called equinoxes — occur around March 20 or 21 and September 22 or 23. Equinox literally means “equal night," since the length of day and night is nearly equal in all parts of the world during the equinoxes.
The March equinox marks when the Northern Hemisphere starts to tilt toward the sun, which means longer, sunnier days. In the Northern Hemisphere, the March equinox is called the vernal equinox, because it signals the beginning of spring (vernal means fresh or new like the spring). The September equinox is called the autumnal equinox, because it marks the first day of fall (autumn).
When the Northern Hemisphere starts to tilt toward the sun in spring, the Southern Hemisphere starts to tilt away from the sun, signaling the start of fall. Thus, in the Southern Hemisphere, the March equinox is called the autumnal equinox, and the September equinox is called the vernal equinox.
People have celebrated the vernal equinox for centuries. For ancient cultures, the vernal equinox signaled that their food supplies would soon return. Early Egyptians even built the Great Sphinx so that it points directly toward the rising Sun on the day of the vernal equinox. In Christianity, the vernal equinox is significant, because Easter always falls on the first Sunday after the first full moon after the vernal equinox.
If you keep your eyes and ears open around the time of the vernal equinox, you're likely to hear or see people talking about a magical phenomenon that only occurs on that day. According to legend, the special astronomical properties of the vernal equinox make it possible to balance eggs on end.
So is there any truth to this popular legend? Nope! It's actually possible to balance eggs on end on any day of the year. It just takes a lot of patience and determination. There's nothing magical about the vernal equinox that makes it any easier to balance an egg on end.
You might be wondering how such an interesting and widespread legend got started. No one knows for sure, but some believe the Chinese may have started the practice of balancing eggs on end during the vernal equinox. Given that day and night are balanced at the time of the vernal equinox, it's possible that the Chinese chose a balanced egg as a symbolic representation of this astronomical phenomenon.