At precisely 1:14 a.m. on March 20, the sun passed directly over the equator, marking the vernal equinox and the start of spring. That's as simple astronomically as it gets, but that of course is Mother Earth's sign to awake from her winter slumber—which is no small thing.
It marks one of two times that night and day are nearly equal in length each year. In the northern hemisphere, this is the first day of spring. In the southern, it's the autumnal equinox, the beginning of fall, and it heralds the onset of winter. And, of course, the two reverse in September.
"Astronomers define an equinox as that moment when the sun arrives at one of two intersection points of the ecliptic (the sun's path across the sky) and the celestial equator (Earth's equator projected onto the sky),” Space.com explains. During the vernal equinox, which occurred at 5:14 Universal Time the morning of March 20, “the sun will be shining directly over the equator from the point of view of a spot in the Indian Ocean, 757 miles (1,218 km) southeast of Colombo, Sri Lanka.”
The changeover from winter to spring actually occurred on the evening of March 19 in the Pacific and Mountain time zones, according to the The Old Farmer's Almanac and Space.com, which also noted that it's the earliest vernal equinox since 1896. Usually the magical moment happens later on the 20th or even on the 21st.
The Indigenous Peoples of the world mark this momentous event in a variety of ways, from heralding a new year to celebrating the beginning of the planting season.
In many countries, the spring equinox is a holiday, and children have off from school. Ceremonies are held at numerous archaeological sites as true believers and new agers flock to appropriate some of the ancient energy that is thought to emanate from the very stones.
Many of the most famous structures in the Mundo Maya, the world of the Mayans, were built around the equinox. Dzibilchaltún and Chichén-Itzá, both on the Yucatan Peninsula, have features that make use of the unique angle of the sun on that day.
On both the spring and fall equinoxes (that will fall on September 22 this year) at the Mayan site Dzibilchaltún—which means "place where there is writing on the stones," according to the magazine Yucatan Today, out of Mérida, Mexico—the sunrise lines up with windows the Temple of the Seven Dolls, so named because of seven effigies found inside the building.
"At the Mayan site of Dzibilchaltún March 21 and September 22 at 5 a.m. is the day and time of the equinox when the sun sends its beams through the two windows of the Temple of the Seven Dolls, providing a lovely spectacle of Mayan exactitude,” Yucatan Today says on its site.
Just outside Mérida, Dzibilchaltún was populated from about 500 B.C. to the 1540s when the Spanish came, the magazine says.
That is just one way that the Maya proved their astronomical prowess. Their crowning achievement is the Pyramid of Kulkulkan, or El Castillo, at Chichén-Itzá. There the famous feathered serpent slithers down the stairs in a show of light that draws thousands to this site annually.
Likewise, the ancient Pueblo of Chaco Canyon knew a thing or two about astronomy. They marked the equinoxes and the solstices by positioning stones to produce sun daggers on each date, according to the Exploratorium museum. Many of their installations had astronomical significance.