Humanity has witnessed solar eclipses since there's been a humanity, but it's only since the scientific revolution that we've understood how to predict them.
Prior to that, cultures around the world had to watch in awed silence as the sun disappeared behind the moon, waiting for the renewal of light. While we have extensive records of eclipse events from ancient China and Babylonia, there has been little documentation of what native American cultures recorded.
Now, a recent survey sheds some light on what the mighty Aztecs thought about the rare and wonderful solar eclipses.
Related: Solar eclipse guide 2020: When, where & how to see them
Enter the Aztec
The Aztec Empire arose in 1428 in south-central Mexico and flourished until the Spanish arrived in 1519. Like all empires, the Aztecs had extensive hierarchies and bureaucracies — and recordkeeping, detailing everything from harvests to wars. Unfortunately, most of Aztec history is shrouded in mystery.
For one thing, the Aztec writing system relied mostly on pictographs and ideographs, many of which we can only guess as to the translation. Second, most of the Aztec records did not survive the Spanish conquest, and the ones that did survive were often (poorly) translated into Spanish.
Still, the empire lasted for nearly a century, so we have some rough sketches of the growth of Aztec culture and the way these people viewed their universe. This we get from the Aztec Codices, the historical manuscripts (some even predating the arrival of the Spanish) that have survived to the present day. Recently, we've even begun to peek into their knowledge of solar eclipses — generally considered a big deal in cultures worldwide — and how they viewed those momentous events, as detailed in a paper appearing in the preprint journal arXiv.
One of the biggest challenges is that the Aztec Codices do not provide precise dates for events. Instead, any interesting events happening in a particular year, like a famine or major war, are simply listed in that year without any specifics. Still, knowing the year (and especially knowing how the Aztecs counted their years) is enough. We can combine modern astronomical tools, which can reliably reconstruct past eclipses going back centuries, and historical records from other civilizations to list the eclipses that the Aztecs might have reasonably had a chance to see, and check if anything lines up.
Superstitions of the sun
Sure enough, the Aztecs took notice of some major solar eclipses in their history. Records appear in the Codices as early as 1301 (before the Aztecs even founded their empire) to right at the time of the Spanish conquest in 1524.
As to what significance the Aztecs attached to eclipses, we can only guess. Other cultures around the world attached immense importance to them — after all, you probably would too if the sun suddenly disappeared in the middle of the day and you didn't know why.
But the Aztecs appeared by and large to be not the greatest or most careful astronomers. They kept track of the seasons, of course (essential for any agricultural civilization) and paid careful attention to the position of Venus. But they did not have a very sophisticated calendar, did not keep track of the other planets and did not make any mention in their writings of any attempts to explain or predict heavenly cycles.
As far as we can tell, Aztecs thought that solar eclipses simply happened, randomly and unexpectedly, and it seems that every time they did the Aztecs thought about them differently.
In one pictograph representing an eclipse, a jaguar — a symbol of darkness — is shown swallowing the sun. The people of the empire had to yell and scream to scare the jaguar away.
However, the Aztecs also believed that the "land of the dead" lay beyond the sky, and was normally hidden by the glare of the sun. Only by challenging the sun could one be granted access. Mercury and Venus, for example, were considered twins in Aztec mythology, and they both had the ability to venture close to the sun, visit the land of the dead, and return unharmed. In one pictograph, the land of the dead can be seen behind the eclipsed sun, a rare view indeed.
But there's more. The Aztec believed in certain creatures of darkness, or demons named "Tzitzimime." These skeletal creatures represented the souls of sacrificed warriors. In one pictograph of an eclipse, two of these demons are shown alongside the dark sun. The fear was that these demons of darkness would consume the sun and then come to Earth, bringing an end to the world as the Aztecs knew it.
Related: The most amazing photos of the 2017 'Great American Solar Eclipse'
Not a big deal
The truth is, we know very little about Aztec mythology. They recorded well over two dozen solar eclipses in their history, but seemed to interpret them differently every time. However, unlike their European and Asian contemporaries, they did not attach much historical significance to these cosmic events.
For example, a typical European king or Chinese emperor might fear for the loss of his throne if an eclipse happened during his reign. The Aztecs did not make this connection, and considered eclipses purely celestial (though potentially world-ending) events.
Still, just like all cultures around the world, the Aztecs took great notice of solar eclipses, and worried about them enough to write about it, ensuring that future generations would know what they saw.
Read more: "Eclipses in the Aztec Codices"
Paul M. Sutter is an astrophysicist at SUNY Stony Brook and the Flatiron Institute, host of Ask a Spaceman and Space Radio, and author of Your Place in the Universe. Sutter contributed this article to Space.com's Expert Voices: Op-Ed & Insights.
Follow us on Twitter @Spacedotcom and on Facebook.