This happened on March 21, 2019, the first full day of Spring. On Wednesday afternoon, March 20 the Spring Equinox of 2019 began.

The photo that I chose shows the day of the Spring Equinox 2020. On March 19, the day of the spring Equinox, the Pyramid of Kukulcan or El Castillo that dominates the Great Plaza at Chichen Itza, reveals its function in ancient times as a solar clock marking the passage of the seasons. It is aligned to catch the rays of the setting sun on the days of the spring and fall equinoxes in March and September. Triangles of light and shadow appear along the side of the north staircase forming the rippling body of a snake. It merges with the head of a stone serpent at the foot of the building, creating the illusion of a gigantic reptile coming down from the sky and slithering across the ground towards the Sacred Cenote.

The light and shadow phenomenon. Testimony of the amazing advance of the Maya in architecture and astronomy is the “light and shadow” phenomenon that takes place on the northern staircase of the Castle during the Spring Equinox on the 21st of March and the Autumn Equinox on the 21st of September. About three o’clock in the afternoon on the days of the equinox the sun projects seven triangles of light onto the balustrade on the northeastern side of the Castle. These begin to move up and down along the balustrade to form the silhouette of a serpent.

This large step-pyramid in the large and famous site of Chichen Itza was dedicated to the Mayan God depicted as a feathered serpent. So precise was the architecture of this building that the setting sun on the spring and fall equinoxes will turn the shadows of the steps into an illusion of a serpent slithering down the banister. Adding all of the steps on four sides to the upper platform step will also equal 365- symbolic of the days in one year.