The spring equinox at Chichén Itzá is famous for the light-and-shadow effect on the pyramid of Kukulkán, where shadows appear to form a serpent descending the staircase. Visitors gather around the equinox to observe this event and connect it with Maya astronomical knowledge.

This item touches archaeology, but the event itself is a nationally known cultural gathering. For citizenship learners, the essential facts are Chichén Itzá, Yucatán, the spring equinox, and the serpent-like shadow of Kukulkán.