IRA FLATOW: Every 260 days, Indigenous communities in the Highlands of Guatemala celebrate a new cycle of the Mayan calendar. This ceremony has persisted for thousands of years, and the latest one of these celebrations happened earlier this month. The Maya have long been accomplished astronomers, and the tradition of using the Sun to keep time persists to this day.

Joining me to tell us about the significance of this astronomical ceremony are my guests, Willie Barreno, Mayan calendar keeper based in Quetzaltenango, Guatemala, and Dr. Isabel Hawkins, astronomer and senior scientist at the Exploratorium in San Francisco, California. Welcome, both of you, to Science Friday.

WILLIE BARRENO: Thank you for having us here today.

ISABEL HAWKINS: Thank you, Ira.

IRA FLATOW: You’re welcome. Willie, tell me about the ceremony and what the significance of it is.

WILLIE BARRENO: Yes, thank you. I think, first of all, we will have to think about monkeys first.

IRA FLATOW: Monkeys?

WILLIE BARRENO: Monkeys are very important for our culture. They are known as the scribes and the ones who keep track of histories, but also they are the masters of art, and pottery, and the Popol Vuh, which is one of the most important books for the Mayans.

So there are two monkeys in the jungles of Guatemala. One is the howler monkey, and the other one is the spider monkey. Both of them are like the ones who see everything from on top of the tree, so what’s going on down there.

So both of them will have four extremities. So if you add 4 and 4, you would get the number 8. So the celebration that it happen just a while ago here in Guatemala, it’s called in English the Eighth Monkey Ceremony, or Wajxaqib’ B’atz.

And that is the representation of the balance between the night and the day. I don’t know if this answer is clear. I just want to make it very poetic because we come from a very poetic language and then very symbolic way to celebrate life.

IRA FLATOW: The ceremony itself, is it actually based on the cycles of the Sun’s movement?

WILLIE BARRENO: Not necessarily. This ceremony, I would say, in this way, it takes place every nine months, average. The calendrical or the mathematical systems for the Mayans and Mesoamericans is number 20. If you multiply 2013 times, then you get a period of time of 260 days, and that’s the average time for a human to be in the mom’s womb, average nine months.

So this is the base of all the astronomical cycles. But then the first one will be multiplied 20 times 13, and then you get 260 days. So every 260 days, we have a day called Eighth Monkey, or Wajxaqib’ B’atz. And that’s when we do this celebration.

IRA FLATOW: Isabel, you’ve been going to these ceremonies for years as an astronomer educated in the Western way. What is it like to observe these ceremonies?

ISABEL HAWKINS: Yeah, it’s really amazing. When I started going to Guatemala was in 2010 when the Smithsonian National Museum of the American Indian asked me to develop a website on Maya astronomy and the Maya calendar because, in 2012, December 21 was when the big count or long count calendar, which spans cycles of 5,215 years, would turn over. The so-called 13 back tunes would turn over.

And then people made up these stories that there would be the end of the world or some catastrophe would happen. And so I agreed to do this calendar website for the Smithsonian under the condition that I would go and interview the calendar keepers in Guatemala. But being there, it’s an amazing entry.

You have to climb up. You start seeing some black smoke up on the hill and this very triangular, pointy cave, where much of the offerings are given really to connect with these cycles and to connect with the energy of the Earth and the power of the Sun and the Moon and the sky. And then from there, the calendar keepers will set up this beautiful altar, a circular altar, that is aligned with Cardinal directions and with key points of the position of sunrise in the Eastern horizon as seen from this cave. And it was using those precise observations that these count of the days has been going on for thousands of years.

IRA FLATOW: Willie, as a calendar keeper, is it true that the Mayan astronomers also predicted astronomical events like eclipses?

WILLIE BARRENO: I think it’s a great question. When you mean predicted, it’s like a forecast. Like today, the Weather Channel forecasts storms, tornadoes, and hurricanes. I think humans have always had that ability in the sense of serving what is going on nature.

My grandmother would say, oh, there’s going to be an earthquake by seeing the clouds. Or there’s going to be a rain also because of seeing just the behavior of the trees. But obviously, 500 years ago when the Europeans arrived, they misunderstood the way that we were checking on time.

And there was hard times when we were called witches because we were able to predict what was going on. But it’s more about forecasting, and this is what I just talk on behalf of my culture, that we have science within our practices. But it had been confused with religions of sacred. And then that’s why communities still believe in what we do, and how we count time, and how we advise the community to behave.

IRA FLATOW: And so how do you forecast an eclipse?

WILLIE BARRENO: By counting with your fingers. [LAUGHS] We have numbers like 148 and 177 to check on Moon eclipses. But longer eclipses, if we have the 260, if we multiply it by 46, we will have something like 11,000 days. And I don’t have the accurate number right now. And that was when solar eclipse will occur.

But then that’s– the base of this is 20 and 13. And then multiply 20 times 13. And then you multiply 46, and then that’s how you get an eclipse.

ISABEL HAWKINS: It’s absolutely incredible how you can gain a tremendous amount of accuracy just through observation. I think that technology, since the Industrial Revolution, has, in a way, enhanced our capacity to do science that is perhaps more focused on particular themes or topics and go deeper. And we use technology for the sake of measurement, precision, and speed.

However, that same technology has, in a way, dulled or taken away our intrinsic capacity as human beings to use our bodies as the instrument of observation. And when you think about 500 years ago, when people were out in the world, out in nature all the time, and the Maya had special people that were the ah kʼin means an expert on time or an expert in the Sun, an expert in the day because [MAYAN] means day, Sun, and time. So [MAYAN] is a prefix that in the Mayan language implies expertise.

So people studied. People were experts. People were scribes. People took count of the days. They observed the Moon, the Sun, and the planets with great precision. And they were able to identify cycles of when the Moon would come back and be in that alignment, the syzygy, which is when the Sun, Earth, and Moon are in alignment.

IRA FLATOW: I’d like to thank my guest, Dr. Isabel Hawkins, astronomer and senior scientist at the Exploratorium in San Francisco, California, and Willie Barreno, Mayan calendar keeper based in Quetzaltenango, Guatemala.

ISABEL HAWKINS: Thank you, Ira.

WILLIE BARRENO: Thank you, Ira.