Saturday, August 12, 2017

Eclipses





Courtesy Nasa/SDO.

Eclipses are exciting events where either the moon passes between the earth -- creating a solar eclipse -- and the sun or the earth passes between the sun and the moon -- creating a lunar eclipse.  Let's take some time to explore the ancient Maya perspective on it.




Eclipse Names
Solar eclipse glyph on the left,lunar 
eclipse glyph on the right. 
In the Dresden Codex, the lunar glyph 
is never without the solar one
Archaeologists think they've found various ways the Maya wrote "eclipse," at least for in the Postclassic Period. For the most popular of these, two "wings" (one mostly dark and one light) go on either side of a smaller sun glyph for "solar eclipse" or moon glyph for "lunar eclipse." The picture on the right shows two examples (from a drawing in Cyrus Thomas's Aids to the Study of the Maya Codices.)
"Pa' k'in" from the Dresden Codex's page 54.
(You may see people call it pa'al k'in.)


The ancient Maya of this period also had phrases they used sometimes to mean an eclipse. Though they could be used to mean real ones, these phrases were more popular when they wanted to say a certain era/length of time had ended. One of the known phrases was "pa' k'in" (thought to be a short form for "pa'al k'in"), which means "broken sun." 


What The Maya Knew About Eclipses
Copy of the Dresden
Codex's page 51. 
There are points in the earth's and moon's orbits where either the sun or the moon go through an eclipse -- these points are called nodes. Eclipses run in a cycle (called the saros cycle that begins again after about 18 years, 11 days, 8 hours. Did the ancient Maya know about these important parts of eclipse math? So far it looks like the answer is no. But they did know how to get close to predicting eclipses.
This glyph may describe
darkness during a solar eclipse.

They'd figured out that about 177/178 days (which makes 6 lunar months) or 148 days (5 lunar months) after an eclipse -- lunar or solar -- an eclipse of the same type as before might happen. You can find examples of these numbers various places. One is the site of Xultun, which has them written on the inside of a building. Another example is the Dresden Codex. 


The Dresden Codex has eight pages (pages 51 through 58) on eclipses. (Which kind of eclipse hasn't been decided for sure.) Archaeologists have found both number 177 and 148 in these pages. There are years' worth of eclipses written down there -- either ones people had seen or ones that had been predicted -- a length of time lasting 11,960 days. People still wonder if it was a chart that could only be used one time, or if the Maya were somehow able to use it again and again, adjusting it when they had to do so.
Depiction of a solar eclipse.
From the Dresden Codex's
eclipse pages.

So if the ancient Maya were able to sort of predict eclipses, did they realize that they were watching planets and their shadows? It seems they didn't. Instead, it looks like they thought solar eclipses (and maybe lunar ones too) happened because a creature was biting the sun. Various old accounts after contact with the Spanish say the Maya -- depending on the community -- thought the creature was an ant, some kind of cat, or Venus. In the codices, there are images of serpent figures that look like they're trying to eat the sun. These serpents may actually be Venus.

How They Observed Eclipses
The ancient Maya may have used a y-shaped stick to help them look at the sky's objects. They May have used mirrors (made from stone they'd polished) to watch eclipses. Bowls filled with water may have been another eclipse watching tool.

What They Meant
The ancient Maya, from what archaeologists can tell, may have thought that eclipses, lunar and solar, were dangerous. It's also possible that they thought a solar eclipse could be the start of the end of the current world. (The Maya believed there had been worlds before this one.) However, it looks like eclipses weren't always seen as dangerous -- it's possible that eclipses were dangerous during certain "dangerous" times. 

To keep the sun from being swallowed, the ancient Maya thought they could stop an eclipse if they made lots of noise -- doing things like making their dogs howl and by beating drums. The noise was supposed to scare off the creature causing the eclipse.


Terminal Classic Record of An Eclipse 

Unless calculations are mistaken, on July 16, 790, the ancient Maya recorded a solar eclipse. The evidence is Stela 3 from the site of Santa Elena Poco Uinic or just Poco Uinic, a site in the highlands of the Mexican state of Chiapas. The eclipse would have happened not long after noon there.



References:

"Totality: The Great American Eclipses of 2017 and 2024"; Mark Littmann & Fred Espenak; 2017

"Cosmology, Calendars, and Horizon-Based Astronomy in Ancient Mesoamerica"; Anne S. Dowd, Susan Milbrath (editors); 2015


"Beyond the “Dresden Codex”: New Insights into the Evolution of Maya Eclipse Prediction"; Vincent H. Malmström


"Daily Life in Maya Civilization" 2nd Edition; Robert J. Sharer; 2009


ASTRONOMY 1210 (O'Connell): INTRODUCTION TO THE SKY AND THE SOLAR SYSTEMMaya Astr 341 Class: Notes on the Maya


Arqueología Mexicana: El símbolo maya para eclipse


NASA: Glossary of Solar Eclipse Terms


Mesoweb: The PARI Journal 13(2), 2012, pp. 3-16: "Exploring the 584286 Correlation between the Maya and European Calendars"; Simon Martin, Joel Skidmore


"Star Gods of the Maya: Astronomy in Art, Folklore, and Calendars'"; Susan Milbrath; 1999


Project Gutenberg: Project Gutenberg's Aids to the Study of the Maya Codices, by Cyrus Thomas


University of Victoria Astronomy: Arif Babul: WELCOME TO MY ASTROCOURSE WEBPAGES: Physics 303: The Mayan Civilization

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