This Is How the Maya Were So Accurate on Eclipses

Ancient Mayan astronomers turned their eyes to the sky and recorded celestial events with a level of precision that continues to impress scientists today. A new study, published Wednesday in Science Advances, sheds fresh light on how the Central American civilization managed to predict solar eclipses with such incredible accuracy, revealing a complex interplay between their lunar calculations and their famous 260-day calendar. Researchers examined the Dresden Codex, believed to be the oldest surviving book from the Americas, to decode a key table that tracks 405 lunar months—roughly 33 years, per Phys.org.

While this table was long thought to be designed only for eclipse prediction, the new analysis suggests it was originally a lunar calendar meant to sync up with the 260-day divinatory calendar central to Maya culture. The study finds that the 405-month cycle, totaling 11,960 days, is an exact multiple of the 260-day cycle, which allowed Maya specialists to anchor eclipse forecasts to their divinatory calendar. Potential eclipses "are typically spaced six lunar months, or about 177 days, apart, which is the interval it takes for the moon to return to the same alignment with Earth and the sun," per Archaeology News.

Instead of discarding old tables and starting fresh, Mayans overlapped them, resetting the next cycle at specific intervals—either 223 or 358 months—before the old one finished. This innovation allowed them to fine-tune predictions and correct for small astronomical errors, keeping the system on track for more than seven centuries. The study matched the table's predictions against a historical record of eclipses visible in the Maya world from 350CE to 1150CE, finding the system could account for every solar eclipse in that span.