Mayan calender

 Maya peoples used their vast natural knowledge to produce complicated calendars that tracked the motion of the celestial objects, the changing of the seasons, and the timing of ritual festivals. The most important calendar was the 260-day Tzolkin, but Maya researchers have also found references to an enigmatic 819-day calendar that has remained unexplained for decades.

Past researchers have suggested that the calendar may relate to the amount of time that it takes for a planet to appear in the same spot in the sky to an observer on Earth, known as a synodic period. This idea works well enough for Mercury’s synodic period of 117 days, which equals 819 when multiplied by seven, but seems to fall apart for the other planets.

Now, John Linden and Victoria Bricker, a team of anthropologists based at Tulane University, believe they have found the answer to this riddle. The researchers propose that “by increasing the calendar length to 20 periods of 819-days a pattern emerges in which the synodic periods of all the visible planets commensurate with station points in the larger 819-day calendar,” according to a new study published in Ancient Mesoamerica.

A Mysterious Mayan Calendar Stumped Scientists For Decades: “A New Study Has Cosmic Answers” - Collective Spark (collective-spark.xyz)