Ancient Astronomy — Part 2
The Stonehenge I wrote about the last post, is a large monumental. But some of these astronomical relics are portable. Something called the Nebra sky disk was found in Bavaria a few decades ago. It almost certainly represents the burial artifact from a very high cast chief in Neolithic times. It’s engraved with star patterns and constellations, and it was a ceremonial object, but it also embedded real astronomy.
If we go to the other parts of the world, we can actually find ancient observatories. The Caracol at Chichen Itza has the appearance of an observatory but that’s misleading, there was no telescope here. It was built over a millennium ago by the Mayans. The Mayans celebrated Venus as a primordial object of their sky and they set their calendar according to observations of Venus over the year. This building was used for sighting Venus. The astronomers of the Mayan court were held in high esteem and the entire culture pivoted around these observations of Venus. This observatory had one of Maya’s main ceremonial sites. Nearby, you can see the great pyramid of Chichen Itza, where the crowd gathered to celebrate an extraordinary time that occurs once a year. On the left-hand side, the rising Sun over the rain forest in the Yucatan Peninsula casts an undulating shadow up the steps, which rises up the steps as a snake would, and that’s indeed the metaphor, and then disappears. This particular shadowing lasts seven or eight seconds and occurs once a year. One day later, the alignment is no longer perfect and the shadow is not cast. So we have every indication that this 10,000-ton monument built over a millennium ago was situated and oriented with a precision of better than half a degree to commemorate the rising Sun on the longest day, an exquisite astronomical landmark of an ancient culture.
Slightly more controversial work done by Aaker astronomers in Southern and Central America has found pyramid complexes where other astronomical alignments have been seen. In all of this work, it’s difficult to be sure of the interpretation because no written language or record of the use or purpose of these monuments is left to us.
Here, we can look at the Hohokam, a tribe that lived here and eventually disappeared about 1,000 years ago. In a canyon and on a high tour of rock or natural cave forms, light is admitted through a slit in the rock and cast a dagger-like shadow on the far face. On that far face, the Native American tribe etched a spiral in charcoal, and the dagger on the longest day passes through the center of the spiral. At the equinoxes, spring, and fall, the dagger passes tangents through the edges of the spiral. So this is yet another form of a solar calendar created by Native Americans.
The idiosyncrasies and specificities of how these calendars are made are not that important. What’s important is that almost every stable culture has chosen not just to commemorate the Sun’s motion, but codify it with exquisite monumental architecture often of great precision.
Sometimes we simply have no record left to us of how ancient people used astronomy. There’s good evidence going back 100 years that native cultures in the Polynesian area were able to travel across the Pacific to Hawaii and even to South America. For a long time, people thought it was impossible that their navigation skills could have led them to dead reckon traveling to an island 1,000 miles away with an accuracy of 10 or 20 miles. But to those cultures, their knowledge of the night sky was exquisite. In fact, the Gilbert Islanders even to this present day live in houses that look like inverted longboats, and when the children are growing up, their parents and relatives put colored objects on the ceiling to teach them the patterns of the night sky so that they might learn navigation even before they can walk.
Very important records come to us from the long unbroken cultures of the world. The Chinese astronomical tradition is extremely strong because China had a nearly two-millennium history of court astronomy, where astronomers made observations, wrote them down, and they were kept by the emperor that lasted that length of time. The Chinese astronomical record as an incredible resource is not fully tapped, because there simply aren’t enough Chinese or Western scholars to interpret all the information. But what we already know says that it contains a rich trove of data on supernovae, variable stars, eclipses, and transient phenomena of the night sky.
Sometimes, a discovery from the ancient world simply blows us away. A few decades ago, an artifact was found in the GNC off the coast of Greece, which puzzled archaeologists. The ship had actually gone down two millennia ago. The artifact that was found crusted with mud, and rusted, and compressed by time seemed to be a mechanical object. It’s in fact an analog computer that codifies in an incredible way the observations of the night sky. It’s called the Antikythera mechanism.
This one object has rewritten the books on the history of engineering. Built this length of time ago from brass and other materials, and includes off-centered gears, and its moving dials on its face codify the positions of the planets including the outermost planets, including their non-circular motions. The Antikythera mechanism uses excentric gears to show that Mars, Jupiter, and Saturn move at a non-uniform rate in the sky. This is also an eclipse predictor, predicting eclipses over timescales of up to 80 years. It’s a showpiece device that was probably being carried across the Aegean in a trading route to trade for other devices or to show how impressive the Greek culture of the time was.
Astronomy is the oldest science. If we look at the oldest human artifacts we have access to, we can see that they cared about the night sky and were tracking the motions of the Sun, the stars, and the moon, often in a quantifiable way to regulate their lives. The richness of the way ancient peoples have understood and worked with the night sky is sobering and a reminder to us that the night sky still exists for us to enjoy.
