The Sun, our nearest star, provides the heat and energy that Earth needs to sustain all life. Next time you walk outside, notice where the Sun is, feel its warmth, and perhaps even notice where the Sun rises and sets in the horizon or behind a familiar building. Through similar and systematic observations, the Maya of Mesoamerica have been tracking the Sun's movements in the sky for thousands of years. Today, more than seven million Maya people live in regions of Mexico, Guatemala, Honduras, Belize, El Salvador, and other countries.

More than two thousand years ago, the Maya created a complex calendar system to organize the events of their world and developed sophisticated mathematics, inventing the zero. They applied their knowledge and observations to time their ceremonies and agricultural cycles. The Maya built extensive cities with monumental architecture, including pyramids that they used to track the stars and predict seasons. Pyramids are called witz—meaning "mountain"—in the Yucatec Mayan language. From a fixed observation station, Maya astronomers tracked where celestial bodies rose and set with respect to their pyramids to understand cyclical motions and measure the passage of time throughout the year.

The equinoxes, the two times of the year when day and night are of equal length, are important astronomical markers to Maya farmers today, dividing the year in the Maya lowlands into the wet and dry seasons and bracketing the agricultural cycle of corn, beans, and squash that still thrive in rural areas of Mesoamerica. On the equinoxes, the two times of the year when day and night are of equal length, the pyramid of Ku'kulkan in Chichén Itzá, Yucatan, Mexico, serves as an astronomical observatory. As the Sun sets, the pyramid's platforms cast a shadow on the side of the staircase, revealing isosceles triangles of lightmdash;making it appear that a feathered serpent, Ku'kulkan, is slithering down the pyramid. In the final moments of the descent, the Sun strikes the snake's head, carved in stone at the bottom of the staircase, and lights it up. Today, thousands of people come to witness this amazing event, which marks the agricultural cycle of native foods from March to September.