Astronomy by the Book

June 27, 2008

So much of what we now attribute to science used to be chalked up to the supernatural. Take the total solar eclipse, for example, which must have seemed like the wrath of the gods, or a frightening portent of doom, to many ancient cultures. It's still an awe-inspiring sight, even though we know it's a natural phenomenon that occurs whenever the Moon passes between the Sun and the Earth such that the Sun is entirely obscured. (You can watch a video of the 2006 total solar eclipse here.) Darkness unexpectedly falls, right in the middle of the day.

Frankly, it's a wee bit freaky, even if you're expecting it every 18 months or so. So imagine how even more spectacular it must have seemed to the Assyrians on June 15, 763 BC. Wikipedia tell me this is the earliest known total solar eclipse (known as the eclipse of Bur Sagale) described in an historically verified document (in this case, an ancient Assyrian text).

Until now, that is! Maybe. I guess it depends on whether you consider Homer's Odyssey (circa 800 BC) to be an historically verified document. A pair of biophysicists at Rockefeller University made science news headlines this week when they published a paper in Proceedings of the National Academy of Sciences USA claiming that Homer's epic poem describes a solar eclipse that occurred in 1178 BC.

According to Constantino Baikouzis and Marcelo Magnasco, the critical line appears towards the end of the epic saga, when the seer Theoclymenus foretells the imminent demise of Penelope's unwanted suitors, who've been pestering her to marry one of them, assuming Odysseus is dead. Depending on which translation you have on hand, Theo predicts the suitors will soon enter Hades, intoning (no doubt with appropriate gravitas), "The Sun has been obliterated from the sky, and an unlucky darkness invades the world." Unlucky indeed, for the suitors, who are quickly dispatched a few passages later by a vengeful Odysseus, who was the hot-tempered jealous sort. Either that, or he was very cranky after 10 years of wandering.

Even closer analysis of the text revealed other astronomical references. For instance, Odysseus navigates his little ramschackle survivor's raft by monitoring the constellations Pleiades and Bootes, and arrives home in Ithaca as Venus rises in the sky, just before dawn. Pleiades and Bootes only appear together in the sky twice a year, the scientists say, in March and September, while Venus rising before dawn would occur about one-third of the time during new moons. There's even a reference to the god Hermes flying west to the island of Ogygia, which Baikouzis and Magnasco interpret as representing the planet Mercury (the Roman name for Hermes). Mercury reverses course from west to east every 116 days. It's a bit flimsy, but some scholars believe that the Greeks used tales of their gods as a way to remember astronomical events, says Magnasco.

This suggests, among other things, that Homer had a much more detailed knowledge of astronomy than historians have given him credit for to date -- indeed, there's little historical evidence that any of the ancient Greeks tracked the movements of stars and planets in detail. In their defense, they didn't have access to a computer. The Rockefeller scientists were able to use commercial software to scan all the new moons (1,684 in all) between the years 1250 and 1125 BC, looking for the astronomical conditions described in the Odyssey.

They were able to narrow it down pretty well, since that combination only occurs about once every 2000 years. Through a process of elimination, they concluded that the eclipse Homer described occurred on April 16, 1178 BC, which does seem to coincide with the historical events in the epic poem. Granted, this is nearly 300 years before Homer actually wrote his masterpiece, but that's the ancient Greek oral tradition for you. The description is pretty vague, like something people had heard described through generations, rather than a firsthand account.

Baikouzis and Magnasco's paper has met with it share of skepticism. But it's fun little twist on ancient star-gazing. The next total solar eclipse rolls around on August 1. You'll have to travel to places like Greenland or western Mongolia to properly see it, but for diehard skywatchers with ample discretionary funds, it'd be well worth the trip. The rest of us can just sit back in our armchairs and engage in this hot new trend of literary astronomy -- a.k.a., astronomy by the book.

Images: (top) The 1999 total solar eclipse, photo by Luc Viatour. (bottom) "Odysseus Overcome by Demodocus' Song," painting by Francesco Hayez. Both via Wikimedia Commons.