Deep in late winter's Stygian days, we begin to yearn for the lambent warmth of spring. The vernal equinox on the Gregorian calendar is also the first day of spring and is known as the spring equinox. Nearly all human societies have celebrated the coming of spring in some way or another. Many celebrations are held on or near the vernal equinox, the day the center of the sun passes over the celestial equator. The equinox is also the time that daylight and nighttime are equal in length, tipping the scales out of darkness and into the light of new beginnings.
A more accurate definition of equinox would state that it occurs when the sun's elliptic, or path, crosses the celestial equator (the astral projection of the earth's equator). When the vernal equinox occurs, the sun is moving to the north from the perspective of someone standing on the earth. The equinox is also the only time of year at which the sun will rise due east and set due west and the only time someone standing on the equator sees the sun passing directly overhead. Contrary to popular belief, day and night are not exactly equal on the equinox. The difference is imperceptible to us, but the period of daylight is actually longer than the period of night. This is because the center of the sun has to cross the equator, and by the time it has done so, there is already daylight.
Thousands of years ago in Egypt, an astronomer named Ptolemy equated the lengths of the seasons with solstices and equinoxes. At the time of his studies, the vernal equinox point was located in the constellation Aries. As a result, the vernal equinox is also known as the First Point of Aries. Over the centuries, the vernal point has moved incrementally across the sky to its current location in the constellation Pisces. The astrological system of study called the Tropical Zodiac is based upon this movement. Ptolemy, and many scholars of his age discerned no difference between the relevance of astrological versus astronomical study.
Ptolemy would likely have followed the Julian calendar, put forth by Julius Caesar in 45 B.C. at the suggestion of Cleopatra's court astronomer. The calendar was based upon a year defined as having 365.25 days. Any discrepancies in time would be fixed by the addition of one extra day every four years, an event known as a leap year. While the Julian calendar was a vast improvement over previous calendars, it was still inaccurate enough that it shifted with respect to the seasons. In 1582 Pope Gregory XIII proposed a new calendar intended to remedy the problems with the Julian calendar. The Gregorian calendar is based on a more accurate measure of the time it takes the earth to orbit the sun, or a Tropical Year, which is 365.24219 days long. Leap years remain to reset the slippage that occurs every year. We still follow the Gregorian calendar today.
The vernal equinox has been a focal point of celebrations for eons. After a long winter with little or no fresh food, people celebrated the new growth of spring. Fields would be sown, animals bred, homes cleaned and vows renewed. Spring is a time of fertility, which Pagans celebrated through the worship of the goddess Oestra, or Ostara. Oestra was the Germanic goddess of fertility, rebirth and spring. Her symbols include the egg and the hare. When Christianity began to supplant Paganism, facets of Oestra were borrowed for the Christian celebration of Christ's resurrection, including the name Easter.
While the vernal equinox is a specific and brief moment in time, its importance in human culture has survived for thousands of years. People from different cultures and religions worldwide still celebrate the arrival of spring with colored eggs, images of hares and feasts. For what could hold more meaning after the passage of the season of death and burial than the celebration of life?